ISWS-73-CIR118

Circular 118STATE OF ILLINOIS

DEPARTMENT OF REGISTRATION AND EDUCATION

Water Quality and Treatment ofDomestic Groundwater Supplies

by JAMES P. GIBB

ILLINOIS STATE WATER SURVEY

URBANA

1973

C O N T E N T S

P A G E

Introduction . . . . . . . . . . . . . . . . . . . 1

Water quality . . . . . . . . . . . . . . . . . . . 1

Sanitary . . . . . . . . . . . . . . . . . . . 1

Mineral . . . . . . . . . . . . . . . . . . . 2

Natural gases . . . . . . . . . . . . . . . . . 8

Water treatment and costs . . . . . . . . . . . . . . 8

Disinfection . . . . . . . . . . . . . . . . . . 10

Iron removal . . . . . . . . . . . . . . . . . . 10

Softening . . . . . . . . . . . . . . . . . . . 12

Methane removal . . . . . . . . . . . . . . . . 13

Hydrogen sulfide removal . . . . . . . . . . . . 13

Summary . . . . . . . . . . . . . . . . . . . . 13

References . . . . . . . . . . . . . . . . . . . . 15

Appendix A — Information requests . . . . . . . . . . 16

Appendix B — Public health offices . . . . . . . . . . 17

Printed by authority of the State of Illinois – Ch. 127, IRS, Par. 58.29(12-73-3000)

(Revised 5-78-3000)

WATER QUALITY AND TREATMENT OF DOMESTIC GROUNDWATER SUPPLIES

by James P. Gibb

Introduction

This circular presents basic information on water quality and treatment ofdomestic and farm groundwater supplies. It describes tests and practicesthat assure a safe sanitary water quality, and discusses in detail the commonminerals and natural gases that are of concern to home water supplies inIllinois. It describes water treatment procedures and equipment for disinfec-tion, iron removal, softening, methane and hydrogen sulfide gas removal,and their costs.

Each year the Illinois State Water Surveyreceives numerous requests from individualsfor advice on locating, developing, or treatinghome or farm water supplies. This report onwater quality and treatment is one of threecirculars designed to provide commonly need-ed information. Circular 116 tells step-by-stephow to plan a domestic water supply and dis-cusses briefly how groundwater occurs andwhere it is available in the state. Circular 117covers wells and pumping systems used forsmall water supplies.

Answers to specific problems not coveredin these publications may be obtained by con-tacting the State Water Survey at Urbana.Appendix A gives the address and instructions.

This study is part of a continuing program ofwater-resource investigations being conductedby the Illinois State Water Survey under thegeneral direction of Dr. William C. Ackermann,Chief, and John B. Stall, Head of the HydrologySection. The report was prepared under thedirect guidance of William H. Walker.

Water Quality

Groundwater in Illinois begins as precipita-tion which falls on the land surface and slowlyseeps downward into the ground. Beforereaching the ground the snow or rain is rela-tively free of bacteria, suspended solids, anddissolved minerals and gases. After it reachesthe ground it picks up various bacteria and

soil particles, and begins dissolving mineralsand gases that it contacts as it moves overor through the earth materials. Soil particlesin suspension are readily noticed as ‘cloudy’or ‘turbid’ water.

As the water continues seeping downward,the soil particles and bacteria picked up atthe land surface are filtered out by the earthmaterials. In most cases, by the time thewater has reached a depth of 5 or 10 feet, ithas been effectively filtered of all bacteriaand suspended solids.

However, as the water continues movingthrough the ground, it dissolves more miner-als and gases from the earth materials, andnone of these are being filtered out. In gen-eral the deeper the water penetrates, or thefarther it moves from the point of recharge(entry into the ground), the more mineralizedit becomes.

Sanitary

Desirable water for farm and domestic useshould be free of harmful bacteria and ofsafe sanitary quality. The most commonlyused indicator of the presence of disease-producing bacteria is coliform bacteria. Whenpresent in water, this germ indicates that thewater may be polluted by human or animalwaste. This means that the water may con-tain disease-producing organisms that live inthe intestinal tracts of man and warm-bloodedanimals. Water from a well is considered safe

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to drink only when tests show that it con-tains no harmful coliform bacteria.

To test for the presence of bacteria, a watersample should be submitted to the Depart-ment of Public Health, Division of Laborator-ies, in a specially prepared bottle which theywill furnish. There is no charge for this lab-oratory service. A list of laboratory locationsand addresses where such samples can be sub-mitted is given in appendix B.

Proper location and construction of a welland water system generally assures contin-uous protection from water-borne diseases.However, coliform bacteria often are intro-duced into a well during the drilling processor when installing or repairing a pump. Batchchlorination or disinfection (described in a latersection) following construction or repair of awell, pump, or distribution system is there-fore recommended.

Continuous chlorination of private watersupply systems in Illinois currently is not acommon practice and usually is not necessary.The majority of the wells in the state appearto be properly located and constructed, andare adequately protected from the entranceof surface water and bacterial contamination.However, if water from a well is muddy ormurky, particularly after periods of heavyrain, it is probable that surface seepage is en-tering the well.

In such cases, the water should be testedfor bacterial contamination, and if pollutionis detected, the well should be repaired toeliminate the entry of surface seepage or itshould be abandoned and filled. Continuouschlorination is not recommended unless asatisfactory (pollution free) well cannot beconstructed. Then the assistance of the StateHealth Department should be obtained.

Mineral

Only a few of the many minerals normallypresent in groundwater are of interest or con-cern to the majority of people using a well asa source of domestic or farm water supply.

The mineral constituents considered in mostWater Survey chemical analyses are: iron, man-ganese, calcium, magnesium, bicarbonate,nitrate, chloride, sulfate, fluoride, and totaldissolved minerals. Gas analyses also are madeon waters suspected of having objectionable ordangerous concentrations of carbon dioxide,oxygen, nitrogen, hydrogen sulfide, andmethane.

Among these constituents, the ones mostcommonly of concern to homeowners are ironand manganese which cause red, brown, orblack staining; calcium and magnesium whichcause hardness and sometimes scale; high con-centrations of iron, chloride, hydrogen sulfide,and total minerals which give a bad taste tothe water or may be harmful to health; andnitrates which in excessive concentrations maybe harmful to infants and create health prob-lems with livestock.

The results of chemical analyses made bythe Water Survey are expressed in milligramsper liter (mg/l), a term replacing the olderequivalent expression of parts per million(ppm) that refers to the pounds of a specificmineral constituent per million pounds ofwater. Analyses made by private chemicallaboratories sometimes are reported in termsof grains per gallon (gpg). One grain per gal-lon is equivalent to 17.1 mg/l. For example,a report of 350 ppm hardness would be thesame as 350 mg/l hardness, and would be20.5 gpg hardness.

The interpretations of any water analysismust of necessity depend on the intended useof the water. The following discussions per-tain mainly to the use of water for generalhousehold purposes. Recommended upperlimits of the various chemical constituents asoutlined in the U. S. Public Health ServiceDrinking Water Standards in 1962 are givento serve as a guide to well owners in evaluatingthe relative quality of their groundwater supply.

Iron. Iron in groundwater occurs naturallyin the soluble (ferrous) state and is commonly

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called ‘clear water iron’ because it cannot beseen. However, when exposed to air, the ironbecomes oxidized into the ferric state andforms fine to fluffy reddish-brown particlesthat will settle to the bottom of a containerif allowed to set long enough. Water contain-ing this type of iron commonly is called ‘redwater iron .’

The presence of iron in quantities muchgreater than 0.1 to 0.3 mg/l usually causesreddish-brown stains on porcelain fixtures andlaundry. In some cases the presence of ironalso supports the growth of ‘iron bacteria,’ usu-ally noted as a slimy red, brown, or black sub-stance which may accumulate in and eventuallyclog the well, treatment units, and distributionpipes.

The effectiveness of domestic water soften-ers often is greatly reduced by the presence ofiron. Generally speaking, only moderate con-centrations of non-oxidized iron (2 to 3 mg/l)can be removed by softeners.

The Drinking Water Standards recommendsa maximum limit of 0.3 mg/l iron to avoidstaining. In Illinois, about 75 percent of thewells have water containing more than 0.3 mg/lof iron. These wells tap all types of aquifers(sand and gravel, limestone or dolomite, andsandstone).

Manganese. Manganese in groundwater occursin the soluble state, and when exposed to air,oxidizes causing annoying brownish or blackstains on porcelain fixtures and laundry. Thestains caused by manganese generally are hard-er to remove than those caused by iron. Man-ganese normally occurs in low concentrations,but even then it and manganese bacteria, aslimy substance similar to iron bacteria, cancontribute to the clogging of treatment unitsand water pipes.

The recommended upper limit of manganesegiven in Drinking Water Standards is 0.05 mg/l.It is estimated that only about 30 percent ofthe wells in Illinois produce water exceedingthis limit.

Hardness. Hardness in water is caused bycalcium and magnesium. These hardness-forming minerals generally are of major im-portance to the user since they affect theconsumption of soap and soap products andproduce scale in water heaters, pipes, andother parts of the water system.

Hard water is objectionable for most domes-tic uses. For example, laundry washed in hardwater may appear gray rather than white, dishesand glassware may appear dingy from unsightlyand perhaps unsanitary deposits, washed andrinsed hair may feel sticky and stiff, and waterheaters may ‘plug up’ or ‘burn out’ sooner thanusual. Hard water scale also may cause over-heating of automotive, truck, and tractor cool-ing systems.

The Drinking Water Standards does not rec-ommend an upper limit for hardness. The dis-tinction between hard and soft water is relative,depending on the type of water a person isaccustomed to. Someone used to a relativelyhard (300 to 350 mg/l) untreated groundwatersource would find most surface water (150 mg/l)to be soft, while a person used to home zeolitesoftened water (0 to 25 mg/l) would find thesurface water hard.

The Water Survey has categorized waterfrom 0 to 75 mg/l as soft, 75 to 125 mg/l asfairly soft, 125 to 250 mg/l as moderately hard,250 to 400 mg/l as hard, and over 400 mg/l asvery hard.

Hardness determinations for over 15,000groundwater samples in Illinois from sand andgravel and bedrock aquifers indicate that hard-ness concentrations of 200 to 600 mg/l aremost common throughout the state.

Figures 1 and 2 illustrate regional trends inthe hardness of water from sand and gravel andbedrock aquifers, respectively. If water soften-ing is being considered, it is advisable to have amineral analysis conducted to accurately deter-mine the hardness content from a particularwell. Procedures for submitting water samplesfor an analysis are described in a later section.

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Figure 1. Average hardness of water from sand and gravel aquifers

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Figure 2. Average hardness of water from bedrock aquifers

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Alkalinity. Alkalinity in Illinois ground-waters normally is present almost entirely inthe form of bicarbonates. On heating, bicar-bonates are converted to carbonates by loss ofcarbon dioxide. These carbonates, being incom-patible with calcium contained in water, forma precipitate or scale of lime or calcium carbon-ate. If both alkalinity and hardness are presentin high concentrations, excessive formation ofscale will occur when the water is heated.

Zeolite softening of such waters usually willeliminate the scale formation. However, thecarbon dioxide released in this process may causethe treated water to be corrosive to water pipesand heaters requiring more frequent replace-ments.

The Drinking Water Standards does not rec-ommend an upper limit for alkalinity. Mostgroundwaters in Illinois have alkalinity concen-trations between 200 and 400 mg/l. Concentra-tions in this range normally are not consideredexcessive.

Nitrates. Nitrates are considered harmful ifpresent in drinking water supplies in excess of45 mg/l, or the approximate equivalent of 10mg/l nitrogen. Excessive nitrate concentrationsin water may cause ‘blue babies’ (methemoglobi-nemia) when such water is used in the prepar-ation of infant feeding formulas. A few caseshave been reported where high concentrationsin livestock groundwater supplies have resultedin exceptionally high mortality rates in babypigs and calves and in abortion instances inbrood animals.

In Illinois practically all of the wells contam-inated with nitrates are less than 50 feet deep,cased with brick or clay tile, poorly sealed, andsituated down-slope from nearby surface sourcesof nitrogen such as feedlots, septic tanks, andprivies. Inorganic nitrogen fertilizer also hasproven to be a source of nitrate pollution insome shallow aquifers, and may become an evenmore significant source in the future as ever-increasing quantities are applied to the farm.-lands of the state.

The treatment of water containing excessiveconcentrations of nitrate poses a difficult prob-lem. Boiling the water does not help, but ratherresults in concentrating the nitrates. Althoughnitrates can be reduced or removed by demin-eralization, this type of treatment generally istoo expensive for domestic water supplies.Where conditions permit, it usually is easier andmore economical to abandon the poor qualitywater source and attempt to find an unaffectedlocation for a new well.

Any well located near a surface source ofnitrogen should be periodically checked to in-sure that the level of nitrates in the water alwaysis below the Drinking Water Standards limit of45 mg/l.

Chlorides. Chlorides generally are present ingroundwater as sodium chloride or calciumchloride. Concentrations greater than about250 mg/l usually cause the water to taste ‘salty.’

Chlorides occur in earth materials in a solubleform that is the source for normal concentra-tions of this mineral in water. Some domesticand industrial wastes also contribute additionaland sometimes proportionately large amountsof chlorides to localized parts of shallow aqui-fers. Sewage effluent, softener regenerationwaste water, road salt, and leachates or liquidwastes from oil fields, chemical plants, garbagedumps, and mining operations are all commonman-made sources of chloride pollution inIllinois.

The Drinking Water Standards recommendsan upper limit of 250 mg/l for chlorides. In thesand and gravel aquifers throughout most of thestate, chloride concentrations are usually lessthan 10 mg/l. However, groundwater from bed-rock aquifers over major portions of the south-ern and western parts of the state may containwater too salty for most domestic purposes.Such waters occur below depths of about 250feet in the south and 350 feet in the west.

Sulfates. Sulfates generally are present ingroundwater in one of three forms: as magne-sium sulfate, sometimes called Epsom salt; as

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sodium sulfate called Glauber’s salt; or ascalcium sulfate called gypsum. Water with ahigh sulfate concentration has a medicinal tasteand a pronounced laxative effect on those notaccustomed to it.

Sulfates also occur in earth materials in asoluble form that is the source for natural con-centrations of this compound. Man-made sour-ces similar to those for chlorides also can con-tribute to sulfate concentrations locally. Coalmining operations particularly are a commonsource of sulfate pollution, as are industrialwastes.

The Drinking Water Standards recommendsan upper limit of 250 mg/l for sulfates. In mostof Illinois sulfates are well below this standard.However, any highly mineralized water shouldbe checked for high sulfate concentrations.

Fluoride. Fluoride in drinking water has beenshown to be associated with the occurrence ofboth dental cavities and mottled tooth enamel ordental fluorosis. The amount of dental cavitiesdecreases as fluoride concentrations increase,but above concentrations of 1.0 mg/l, the inci-dence of fluorosis or darkened and mottled teethincreases.

State legislation was enacted on July 18, 1967,requiring that all municipal and public watersupply systems in Illinois maintain a fluoridecontent in their finished water between 0.9 and1.2 mg/l. However, this type of treatment isexpensive and generally impractical for individ-ual home water supply systems.. A more prac-tical method for obtaining the dental health ben-efits of fluoride probably would be to have peri-odic fluoride treatments from a dentist.

The Drinking Water Standards recommends1.0 mg/l as the optimum concentration offluoride. The fluoride content of groundwaterfrom most sand and gravel or dolomite bedrockaquifers of the state normally is less than theoptimum level. However, fluoride concentra-tions between 2 and 5 mg/l, well above the rec-ommended level, are not uncommon in ground-water from the deep sandstone and limestoneaquifers in parts of western Illinois, particularly

The Drinking Water Standards recommendsthat water should not contain more than 500mg/l total dissolved minerals. Total dissolvedmineral determinations for over 16,500 ground-water samples from sand and gravel aquifersand 14,200 groundwater samples from bedrockaquifers throughout Illinois show that 50 per-cent of the samples from both types of aquiferscontained less than 500 mg/l; 45 and 39 percent,respectively, contained between 500 and 1000mg/l; and 5 and 11 percent had greater than1000 mg/l.

Most samples that contain more than 1000mg/l of total dissolved minerals have been fromwells tapping deeply buried aquifers that areisolated from effective fresh-water recharge sour-ces by thick and relatively impermeable over-lying materials. Throughout most of central andsouthern Illinois, groundwater from below depthsof about 400 feet generally is too highly min-eralized for most domestic uses. In the north-ern one-third of the state, however, groundwaterof acceptable mineral content may be obtainedto depths of 1500 feet or more.

In general, water containing more than 500mg/l total dissolved minerals will taste slightlymineralized. However, the general public canbecome accustomed to the tastes of water up toconcentrations of 2000 mg/l. Water containingmore than 3000 mg/l generally is not acceptablefor domestic use, and at 5000 or 6000 mg/l totaldissolved minerals livestock may not drink thewater. At about 15,000 mg/l total dissolvedminerals, water becomes harmful to humans andanimals and could be fatal if used continuously.Sea water contains about 34,000 mg/l total dis-solved minerals.

in Fulton, Knox, and Peoria Counties.

Total dissolved minerals. The total dissolvedmineral content in groundwater is a measure ofall the mineral ingredients in the water. Waterwith a high mineral content may taste salty orbrackish depending on the types of minerals insolution and their concentrations. The taste ofwater also depends to some degree on the qual-ity of water an individual is accustomed to.

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Gases in groundwater are important to theuser only when they are present in concentra-tions sufficient to create an explosion hazard,to be offensive in taste or odor, or to be corro-sive. Methane and hydrogen sulfide are thegases most likely to be present in objectionablequantities in Illinois groundwater.

Methane gas may be encountered in somegroundwaters in Illinois (see figure 3) and, if notproperly handled, can present an explosion haz-ard. This gas is colorless, odorless, and tasteless;it is lighter than air and flammable.

When methane is allowed to escape from waterand mixes with air to concentrations of 5 to 15percent methane, the resulting mixture is highlyexplosive if ignited. For this reason, if methaneis present in a water supply, all possible pointsof gas accumulation such as the well house, pres-sure tank, water heater, treatment units, andhigh points in the distribution system should bevented. All vents should extend to the outsidebecause an inside vent can easily lead to a 5 to15 percent explosive methane-air mixture.

In areas of methane gas occurrence, all newwells should be checked for this gas by the dril-ler before they are placed in service. Further-more, because of the danger of asphyxiation, noone should ever enter a large-diameter bored ordug well without first checking for the presenceof methane or other potentially harmful gasessuch as carbon dioxide.

The occurrence of methane in groundwatersappears to be associated with water from thesand and gravel deposits above the bedrock. However, in a few isolated cases methane has beenproduced by wells that tap dolomite or lime-stone aquifers directly overlain by sand andgravel. Methane is believed to be derived fromburied soil zones and organic matter within theglacial drift. It is contained beneath imperme-able till and clay zones typically present in suchdeposits. Recorded occurrences of methaneusually have coincided with the end morainesof the Wisconsinan period of glaciation illus-trated in figure 3.

Natural Gases

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Hydrogen sulfide when present in water inconcentrations greater than 0.2 mg/l causes thewater to have a mild to strong odor of rotteneggs. It is not explosive. This gas is more com-monly found in water obtained from wellstapping limestone or dolomite bedrock forma-tions. Hydrogen sulfide normally is removed bychlorination or aeration.

Water Treatment and Costs

Plans for treating groundwater for domesticor farm uses generally should include consid-eration of: disinfection to insure a safe sani-tary quality, iron removal to prevent stainingof porcelain fixtures and laundry, softening toremove objectionable concentrations of cal-cium and magnesium, and aeration to eliminateoffensive or harmful gases. In some cases,where the groundwater is too highly mineral-ized for human consumption, demineralizationof limited quantities of the water for drinkingand cooking may be justifiable.

To accurately determine the type of treat-ment that may be desired, water samplesshould be submitted for bacterial and mineralanalyses. Instruction for submitting samplesfor bacterial analysis can be obtained from theIllinois Department of Public Health ( s eeappendix B). Water samples for mineral anal-ysis can be submitted to the State Water Survey.

More than 26,000 chemical analyses ofwater samples from wells in Illinois have beenmade by the State Water Survey since 1895.Presently about 1000 groundwater analysesare made each year by Water Survey chemists.This service is free to citizens of Illinois.

To submit a water sample for mineral anal-ysis to our organization, the following pro-cedure should be followed and the appropriateinformation supplied :

1 ) Collect the sample in a clean (not necessarily

sterile) quart size glass jar.

2 ) If possible, collect the water before it enters the

pressure tank.

3 ) Let the water run for a period of 10 or 15 min-

Figure 3. Areas where methane gas is commonly found

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6)

4)

5)

utes to insure that the water collected is represen-

tat ive of water from the well , and not water that

has set in the pressure tank for a period of time.

Rinse out the jar with the running water and

collect the sample and seal it for shipping.

Mail the sample to:

Il l inois State Water Survey

P. O. Box 232

Urbana, I l l inois 61801

Include your name and address, the legal loca-

t ion of the well sampled ( the nearest quarter of

a quarter sect ion, township, range, and county) ,

the depth of the well , and the date collected.

7) If you are interested in a particular mineral con-

st i tuent , also indicate which one and why.

Disinfection

The Illinois Department of Public Healthrecommends disinfection procedures that arebased on use of a strong chlorine laundrybleach (batch or shock chlorination). Thecorrect amount to use can be determined fromtable 1, as explained in the instructions thatfollow.

New wells, or old installations after rehabil-itation, usually are bacterially contaminatedand should be disinfected prior to being placedin service.

1 ) Measure the depth of water in the well if possible.

If this cannot be done, consider the well ful l of

water, for in most cases a slight overdose of

chlorine does no harm.

2 ) Determine the amount of laundry bleach (from

table 1) and mix this quanti ty in about 10 gal-

lons of water . For example, a 6-inch well with

75 feet of water would require 3 cups of laundry

bleach (5.25 percent chlorine) . If the well depth

is not known, use ½ gallon bleach for a drilled

well and 1 gallon for a bored well.

3 ) Pour this solution into the well between the

casing and the drop pipe. (This wil l involve

removing the cap from the pi t less adapter unit . )4 ) Connect one or more hoses from faucets on the

discharge side of the pressure tank to the top

of the well , and while pumping the well , let

water from these f low back into the well for at

least 15 minutes. Then open each faucet in the

system and let the water run unti l a chlorine

odor or taste is noted. Close al l faucets. Seal

the top of the well .

5 ) Do not use the system for several hours, prefer-

ably overnight , to insure adequate contact t ime.

6 ) Flush out the system by discharging water from

all outlets until all chlorine odor and taste dis-

appear. Faucets or f ixtures discharging to septic

tank systems should be thrott led to a low flow,

or temporari ly diverted to an outside discharge

point , to avoid overloading the disposal system.

Diameterof well(inches)

23468

101 21 82 43 03 64 86 0

Amount of chlorine (cups) forgiven depth of water in well (feet)

5 10 25 50 75 100

0.5 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 1.0 1.00.5 0.5 0.5 1.0 1.5 2.00.5 0.5 1.0 2.0 3.0 4 . 00.5 1.0 2.0 3.5 5.5 7.01.0 1.5 3.0 6.0 9.0 12.01.0 2.0 4.0 8.0 12.0 16.02.0 3.5 9.0 18.0 27.0 36.53.0 6.5 16.0 32.5 48.5 64.55.0 10.0 25.0 50.5 76.0 –7.0 14.5 36.0 72.5 – –

13.0 26.0 64.5 – – –20.0 40.3 – – – –

Table 1. Recommended Chlorine Dosagesfor Well Disinfection

Continuous disinfection requires equipmentthat will inject or add chlorine to all waterdrawn from the source. The chlorine mustbe thoroughly mixed with the water, and thensufficient chlorine contact time must be pro-vided to kill all disease-causing and nuisanceorganisms. A minimum of 15 minutes of

Continuous chlorination of domestic or farmwater supply systems is not a common practicein Illinois. As previously mentioned, most wellsin the state are properly located and constructedso that they are adequately protected from theentrance of surface water and bacterial contam-ination. However, if constant protection frombacterial contamination is necessary, continuouschlorination can be investigated. The IllinoisDepartment of Public Health should be con-sulted for advice on this subject.

Chlorine always should be used outdoors orin well-ventilated places because breathing thefumes is dangerous. In heavy concentrations,chlorine also is harmful to skin and clothing.

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contact time usually is recommended in aprivate water system. A chlorine residualshould be present after the 15-minute contacttime. Whenever continuous chlorination isused, it is advisable to measure the chlorineresidual in the treated water every few daysto insure that the system remains bacteria free.Chlorine residual test kits are inexpensive andcontain detailed instructions that should befollowed exactly.

Several types of chlorinators are available,but the most reliable is the water-flow-actuatedpositive displacement type. This type uses apump to inject the chlorine solution, can beadjusted during operation and synchronizedwith the well pump, and is especially desirable

in systems where the water pressure is low andfluctuating. A positive displacement chlorin-ator that feeds chlorine solution in proportionto the actual flow rate maintains a more uni-form chlorine residual than a chlorinator thatis electrically operated when the pump startsand stops. A water-flow-actuated chlorinatorshould always be used when two or morepumps discharge into a single intermediatestorage reservoir.

Nonpositive displacement chlorinators gener-ally are not reliable because of the varyingflow rates and pressure conditions and because

of frequent clogging with deposited minerals.All chlorinator equipment should be frequentlychecked to insure proper operation.

Commercially available chlorinators or chem-ical feed pumps normally cost about $200.Amortized over a five-year period (the expectedservice life) at an interest rate of 8 percent andadding $10 a year for operating and chemicalcosts results in an annual cost for continuouschlorination of about $60.

Iron Removal

More than 75 percent of the groundwatersupplies in Illinois contain iron concentrationsin excess of the recommended 0.3 mg/l level.In such supplies, improvement of water qualityalmost always can be realized by the use of

iron removal equipment.

The most commonly used iron removal pro-cess for domestic use in Illinois is an oxidizingiron filter unit. Other types of units includechlorination-filtration and aeration-settling.

In all of these processes, soluble (ferrous)

iron is converted into its precipitated (ferric)form by some type of oxidizing agent (man-ganic oxide, chlorine, or air) and then removedby settling or filtration. Ion exchange watersoftening equipment rarely is successful inremoving the quantities of iron commonlypresent in Illinois groundwaters.

In the oxidizing iron filter process, raw wateris forced through a filter bed of manganese

green sand that has a manganic oxide film on

the filter grains. This film is created by treat-ing the filter material with potassium perman-ganate. Soluble iron is precipitated by themanganic oxide and retained on the filter ma-terial. Periodic backwashing of the filter isrequired to remove the accumulated iron oxide.Regeneration of the filter material with potas-sium permanganate is usually required after 4or 5 backwashings.

In the chlorination-filtration process, chlorineis added as the water is pumped from the wellto oxidize the iron. Then the oxidized iron isremoved with a sand or carbon filter. Eitherof these filters will remove the oxidized iron.However, a carbon filter has an added advan-tage of also removing most objectionable tastesand odors .

In the aeration and settling process, the dis-

solved iron is exposed to oxygen in a forcedair or gravity aerator before it enters a storagetank. The added oxygen causes the iron toprecipitate and settle to the bottom of the tankfor periodic removal. If this method of irontreatment is used, frequent sampling of thetreated water is recommended to detect if bac-teria is entering the water during aeration.

Efficient iron removal units can be purchasedfrom reputable water conditioning equipmentdealers throughout the state. Many of these

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dealers also install and service iron removalequipment on a rental basis at a nominal charge.If large concentrations of iron and manganeseare present in the water supply, it is oftenadvisable to rent the treatment equipment fora considerable time before purchase to insurethat it will effectively remove the quantitiesof mineral involved.

Iron bacteria problems also may arise inwater containing excessive iron concentrations.Bacterial slime accumulation will cause rapidclogging and exhaustion of iron filter and wa-ter softening units. Occasionally it may sloughoff the inside of the plumbing system andcause discharges of extremely turbid red water.Iron bacteria sometimes can be eliminatedfrom a well and water system by well recon-struction and shock chlorination. However,most infected systems will require either per-iodic shock chlorination or continuous chlor-ination.

The various types of iron removal equip-ment available vary in cost depending on theirsize and effectiveness. It is quite possible thatthe setup for a basic aeration and settling pro-cess could be constructed from existing equip-ment at a very small cost. Commerciallyavailable oxidizing iron filter units may rangefrom $475 to $700 depending on the manu-facturer and size of units. The annual cost foroperating and maintaining an oxidizing iron fil-ter unit is estimated to be from $140 to $200.These values include the amortized cost of theinitial investment, regeneration chemicals andwater, and maintenance costs.

Softening

The hardness-forming minerals in groundwaterfrom nearly all aquifers in Illinois generally arehigh enough to be objectionable. These min-erals (calcium and magnesium) usually can beremoved from a domestic water supply systemwith an ion exchange type home water softener.

The ion exchange softener works like this.As hard water passes through the exchange ma-terial in the softener tank, calcium (Ca++) and

The effectiveness of a softener can be reducedsubstantially when the water contains iron. Thesoftener’s exchange material may become coatedwith iron deposits, which reduces the softener’soverall efficiency. If the water contains iron inexcess of about 2 mg/l, an iron removal unitshould be used ahead of the softener, for opti-mum operation.

Persons with hypertension or high bloodpressure are sometimes placed on ‘low sodium’or ‘sodium-free’ diets by physicians. Shouldthe question of drinking softened water con-taining sodium salts arise, a calculation of thesmall amount of sodium taken into the bodythrough drinking and cooking with softenedwater can be made by the patient’s physician.

Another point of caution about softened

magnesium (Mg++) are exchanged for sodium(Na+) on the surface of the synthetic resin. Thewater leaving the unit still contains essentiallythe same amount of dissolved minerals, but thehardness-forming minerals have been replacedwith sodium.

When the softening material’s ability to ex-change sodium for calcium and magnesium isexhausted, it must be ‘regenerated’ by runninga given amount of salt brine (sodium chloride)through the softener tank. The exchange ma-terial trades back its load of calcium and mag-nesium taken from the hard water for sodiumfrom the salt brine. The spent brine solution,now containing the calcium and magnesium,is flushed from the softener tank by back-washing and the unit is ready to start itsregular cycle once more.

Brine from the regeneration of a fairly largecapacity household softener may be dischargedinto the average septic tank and tile field, ifthe septic tank is properly sized. However, ifthe septic tank is unusually small, it may beadvisable to install a smaller softener unit. Asmaller softener will require less brine solutionduring each regeneration cycle so that shockoverloading of the sewage disposal system willbe minimized.

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water from a domestic type softener should

be noted. As the hardness of water approaches0 mg/l (often produced immediately afterrecharging of a domestic softener) the tendencyfor the water to become corrosive increases.

Home water softeners generally are rated by

the total grains of hardness they can removefrom the water before the exchange materialsmust be regenerated. Most domestic sizedsofteners used in Illinois have rated capacitiesbetween 10,000 and 20,000 grains per regener-ation cycle. For a typical hardness contentof 350 mg/l (about 20 grains), a 20,000 grainsoftener should be capable of softening about1000 gallons of water before regenerationwould be necessary. This amount of softenedwater would furnish an average family of 3 or4 persons (using 50 gpd per person) approxi-mately 5½ days.

Commercially available water softening unitsmay be expected to cost from $425 to $625.The annual cost of operating and maintainingan ion exchange home water softening unit forwater containing 350 mg/l hardness is estima-ted to be from $106 to $160. This includesthe amortized cost of the initial investment,regeneration chemical and water, and mainten-ance costs.

Methane Removal

Methane gas can be removed from a do-mestic water supply system by several methods.However, it is recommended that the adviceand services of a drilling contractor or plumberexperienced in treating water containing me-thane be obtained to insure that the explosionhazard which can result from the presence ofthis gas will be minimized.

One generally accepted method for removingmethane is aeration. An aerator consistingof 3 or 4 metal trays with perforated bottomspositioned one over another at about 1-footspacings can be used. Each tray is filled to adepth of about 8 or 10 inches with pieces ofcoke having an average size of about 1½ inches.For good design the total tray area should be

about 1 square foot for each 2 gallons per min-ute pumped from the well. Provisions for aheater to eliminate freezing during cold periodsalso should be considered. The aerator shouldhave a water-tight roof but the sides should beleft open except for a covering of fine meshscreen (24 meshes per inch) to protect thewater from direct contamination of flying in-sects and debris.

Water is pumped directly from the well tothe top tray of the aerator and is allowed totrickle down through each tray of coke. Themethane is released to the air and is dissipatedthrough the sides of the aerator. Water at thebottom of the aerator collects on a water-tight tray and flows by gravity into a storagereservoir. A small pressure pump may then pickup the water from the storage tank and placeit under pressure in the normal type pressuretank. Water treated in this manner should betested frequently to determine if any air-bornecontamination is occurring during aeration.

Hydrogen Sulfide Removal

The most commonly used method for re-moving hydrogen sulfide gas is continuous chlor-ination followed by an activated carbon filter.This method can handle relatively large quanti-ties of hydrogen sulfide and does not releaseodor to the air. Some manufacturers have rec-ommended using only the activated carbonfilter. However, this type of treatment iscapable of handling only very small concentra-tions of hydrogen sulfide and it is suspectedthat the filters have relatively short life span.

Hydrogen sulfide gas also can be removedfrom water for domestic uses with the sametype of aerator described for removing methanegas. However, because of the bad odor givenoff by this method, it is not always a desirableway of removing hydrogen sulfide.

Summary

Desirable water for general domestic useshould be of a safe sanitary quality and should

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contain no objectionable or dangerous concen-trations of minerals or gases. Many of thewells in Illinois appear to be properly locatedand constructed and produce water containinglittle or no harmful bacteria. It is still advis-able, however, to have periodic bacterial anal-yses run on well water that is being used fordrinking and cooking. If bacterial pollutionpersists, a search for a safe sanitary supplyshould be undertaken.

Objectionable concentrations of iron andhardness are common in waters obtained fromall aquifers in Illinois. In the past, tolerancerather than treatment of high concentrationsof these minerals has been the common prac-tice. Today, an increasing number of privatewater supply systems are being equipped withcommercially available home treatment units.It is most probable that the general qualityof water from all private water supply systems

could be improved with the installation ofsimilar equipment.

High concentrations of objectionable naturalgases such as methane and hydrogen sulfide

have been noted in isolated areas in Illinois. Ade-quate ventilation throughout the distributionsystem, aeration, or chlorination normally canremove these objectionable gases.

The cost of producing raw groundwater fordomestic use has been estimated to be about$3 per 1000 gallons or $219 per year for a familyof 4 persons using 50 gpd per person. The addi-tional yearly costs of softening and iron removalvaries considerably depending on the quality of

water to be treated and size of treatment unitsused.

For a typical water (hardness of about 350mg/l and iron content of 3.0 mg/l or more), theannual costs for relatively small capacity unitsis estimated at about $140 each for softening andiron removal. Annual costs of larger units maybe as high as $200 for each type of treatment.The annual cost for continuous chlorination isabout $60.

Finished water from a private groundwatersupply system incorporating all three types oftreatment is estimated to cost about $7.75 per1000 gallons, or about $560 per year for thefamily of 4.

1 4

References

A new world of softness. 1969. Sears , Roebuck and Company.

Buswell, A. M., and T. E. Larson. 1937. Methane in ground water .Journal of American Water Works Association v. 29(12): 1978-1982.

Gibb, James P. 1973. Planning a domestic groundwater supply system.Illinois State Water Survey Circular 116.

Gibb, James P. 1973. Wells and pumping systems for domestic watersupplies. Illinois State Water Survey Circular 117.

Gilliland, Edwin R. 1965. The current economics of electrodialysis.U. S. Department of the Interior.

Hydrogen sulphide removal from well water. 1968. Soil and Water 2.Agricultural Engineering Extension, Ohio State University, Columbus.

Iron removal from well water. 1968. Soil and Water 3. AgriculturalEngineering Extension, Ohio State University, Columbus.

Larson, T. E., and H. A. Spafford. 1947. Water treatment for thesmall homes or farms. Illinois State Water Survey Circular 25.

Larson, T. E. 1963. Mineral content of public ground-water suppliesin Illinois. Illinois State Water Survey Circular 90.

Meents, Wayne F. 1960. Glacial drift gas in Illinois. Illinois StateGeological Survey Circular 292.

Private water systems. 1968. Cooperative Extension Service, IowaState University, Ames, Iowa.

Salinity and livestock water quality. 1959. South Dakota StateCollege Agricultural Experiment Station Bulletin 481.

Spafford, H. A., and C. W. Klassen. 1937. Hazards of methane gasin water wells and suggested method for elimination. IllinoisDepartment of Public Health mimeograph report.

Strawn, Bernice. 1963. Iron in your water supply. Coope ra t i veExtension Service, Oregon State University, Corvallis, Oregon.

Water conditioning technical manual. 1965. F. E. Meyers & Bro. Co.

Water system and treatment handbook. 1965. Water Systems Council,Chicago, Illinois.

Water treatment. 1961. Technical Manual 2. Water SystemsCouncil, Glenview, Illinois.

Water well construction code, rules and regulations. 1967. IllinoisDepartment of Public Health.

Water well pump installation code, rules and regulations. 1967. IllinoisDepartment of Public Health.

Wilke, Harvey, and Ruth Hutcheson. 1962. Water softening for thehome. Cooperative Extension Service, Purdue University, Lafayette,Indiana. Extension Circular 505.

Wilke, Harvey, and Ruth Hutcheson. 1965. Iron water control forthe home. Cooperative Extension Service, Purdue University,Lafayette, Indiana. Extension Circular 507.

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APPENDIX A – INFORMATION REQUESTS

Groundwater information requests should be accompanied by asmuch of the following data for each type of request as possible.

For a new supply

Information requests should be accompaniedby the following data:

1 ) The legal location of the proposed well siteto the nearest quarter of a quarter section,township, range, and county (for example,NE¼ of the NE¼, Section 10, T 16 N,R 6 W, Sangamon County).

2 ) Estimated daily water requirement (ingallons) or explanation of planned use (forexample, domestic supply for 4 persons,10 head of cattle, and 100 head of swine).

3) Information on existing wells located in thevicinity of the property (depth, adequacy,quality of water, etc.).

For existing well problems

Information requests should be accompaniedby the following data:

1 ) A complete explanation of the problemincluding any recent changes in pumpingequipment, water use, etc.

2) Complete information on the well(s)including:a) Legal location of the well to the nearest

quarter of a quarter section, township,range, and county.

b) Distances from potential sources ofpollution (septic tank, feedlots,privies, sewer lines, etc.).

c) Type of well (dug, bored, drilled, etc.).d) Depth of well (in feet below land surface).e) Water levels (in feet below land surface)

before and during pumping. Include thepumping rate (in gallons per minute orgallons per hour).

f) Capacity, make, and type of pump ( forexample, 3 gallons per minute, Red Jacketdeep well jet).

g) Depth to bottom of pump intake.h) Driller’s log of well.i) Casing length and diameter.j) Screen length, diameter, and slot size.

For water quality informationor problems

Information requests concerning the chemicalquality of water should be accompaniedby the following:

1 ) Complete information on the well asdescribed above.

2 ) A one-quart water sample from the well.a) The sample should be collected at a

point in the system located on the wellside of any pressure tank or water treat-ment equipment (filter, softener, etc.).

b) Collect the sample after the well hasbeen pumped for about 10 or 15minutes to insure that the water samplecomes directly from the water-bearingformation and not from storage.

Information requests to the State Water Survey should be sent to:

Illinois State Water SurveyWater Resources BuildingP. O. Box 232Urbana, Illinois 61801

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APPENDIX B – PUBLIC HEALTH OFFICES

Addresses

Illinois Department of Public Health4302 North Main StreetRockford, Illinois 61103

Phone 815-877-8051

Illinois Department of Public Health5415 North University AvenuePeoria, Illinois 61614

Phone 309-691-2200

Illinois Department of Public HealthBox 91048 West Galena BoulevardAurora, Illinois 60507

Phone 312-892-4272

Illinois Department of Public Health1919 West TaylorRoom 809Chicago, Illinois 60612

Phone 312-341-7290

Illinois Department of Public Health4500 South SixthSpringfield, Illinois 62706

Phone 217-786-6882

Illinois Department of Public Health2125 South FirstChampaign, Illinois 61820

Phone 217-333-6914

Illinois Department of Public Health9500 Collinsville RoadCollinsviile, Illinois 62234

Phone 618-345-5141

Illinois Department of Public Health2209 West Main StreetMarion, Illinois 62959

Phone 618-997-4371

Regional Offices

Counties Served

Carroll, De Kalb, Jo Daviess, Lee, Ogle, Stephenson,Whiteside, Winnebago

Bureau, Fulton, Henderson, Henry, Knox, La Salle,Marshall, McDonough, Mercer, Peoria, Putnam,Rock Island, Stark, Tazewell, Warren, Woodford

Boone, Du Page, Grundy, Kane, Kankakee, Kendall,Lake, McHenry, Will

C o o k

Adams, Brown, Calhoun, Cass, Christian, Greene,Hancock, Jersey, Logan, Macoupin, Mason, Menard,Montgomery, Morgan, Pike, Sangamon, Schuyler, Scott

Champaign, Clark, Coles, Cumberland, De Witt,Douglas, Edgar, Ford, Iroquois, Livingston, McLean,Macon, Moultrie, Piatt, Shelby, Vermilion

Bond, Clinton, Madison, Monroe, Randolph, St. Clair,Washington

Alexander, Clay, Crawford, Edwards, Effingham,Fayette, Franklin, Gallatin, Hamilton, Hardin, Jackson,Jasper, Jefferson, Johnson, Lawrence, Marion, Massac,Perry, Pope, Pulaski, Richland, Saline, Union, Wabash,Wayne, White, Williamson

Regional Laboratories

Illinois Department of Public Health1800 West FillmoreChicago, Illinois 60612

Illinois Department of Public HealthP. O. Box 2467Carbondale, Illinois 62901

Illinois Department of Public Health134 North Ninth StreetSpringfield, Illinois 62706

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