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Before You Construct a Water WellFacts a homeowner should know
Report 68-3(First Revision 1972)(Second Revision 1975)(Third Revision 1981)(Fourth Revision 1990)(Fifth Revision 1997)(Sixth Revision 2001)(Seventh Revision 2004)
This document is also available on the web at: http://www.gov.ns.ca/enla/water
Halifax, Nova Scotia2004
Environment and Labour
PrefaceThe cost of a well is usually small in comparison toa house itself, but a home is worth little without agood water supply. This booklet has been preparedfor prospective homeowners and others who mayhave to have a wellconstructed. The morefamiliar you are with theinformation in thisbooklet, the more likelyyou are to be satisfiedwith your well and withyour home.
Nova Scotia Department of Environmentand Labour administers the Well
Construction Regulations. A list ofregional offices is provided for your
convenience at the end of this booklet.Staff will be happy to provide general
information or to answer specificquestions regarding wells, water supply
potential, and the Regulations.
Table of ContentsA Water Supply in Your Home
What is Groundwater? 1How Does Groundwater Occur in Nova Scotia? 2
Planning A Water SupplyWhy Should I Have a Water Well Constructed Before I Build? 3Where Do I Obtain Background Information for My Area? 4How Much Water is Enough? 7Where Should My Well Be Located? 8
Contracting The JobHow Do I Select A Water Well Contractor? 9What Items Should Be Covered In The Contract? 9Final Well Inspection 10
Components Of A Water Supply SystemThe Well 12
What is a Drilled Well? 12What is a Dug Well? 14
How Long Should Well Yield Tests Be? 15The Pump 16
How do I Select a Pump? 16How do I Select a Pump Installer? 16
The Water Storage (Pressure) Tank 18The Distribution System 19The Treatment System 19
Water QualityWhy Should I Test? 20What is Bacterial Quality 20
How Do I Test for Bacteria? 20What Do The Results Mean? 21
What is Chemical Quality 23How Do I Test for Chemical Quality? 23What Do The Results Mean? 24
Water Treatment 26
Well MaintenanceHow Often Should I Check Water Quality? 27How Can I Protect my Water Supply for the Future? 27
Appendix 1Disinfection of Water Wells by Chlorination 30
How do I Disinfect my Well? 30Sampling After Disinfection 31Final Notes 31
Appendix 2Volume of Water in Wells 32
Nova Scotia Environment and Labour Regional Offices 33
Notes or Sketches 34
Sample Drilled Well Contract 35
List of Figures1. The Hydrologic Cycle 12. Groundwater Regions of Nova Scotia 23. Dry Shallow Wells in Subdivisions 34. Problems Encountered in Drilled Well Construction 45. Drilled Well Report 56. Dug Well Report 67. How Much is Enough? 78. Example of a Complete Water System 119. Common Defects of Well Construction with Remedies 1310. Cross Section of a Typical Dug Well 1411. Pump Installation Report 17
List Of Tables1. Guidelines for Selected Chemical Parameters 242. Common Water Quality Problems and Possible Solutions 26
A Water Supplyin your Home Water is the basis of life.You cannot survive withoutit. In the past, there was little difficulty in findingsufficient water for the limited household needs.However, indoor plumbing and automatic appliancesplace much greater demands on water supply today.As a conservative estimate, a home will need in theorder of 340 litres (75 imperial gallons) per personper day to meet all these needs.
A household needs not only enough water, but alsowater that has good bacterial and chemical quality.
About half of Nova Scotians rely on groundwater forwater supply. The most common water supply forthe home that is not served by a public system is adrilled well. In rural areas, three quarters of newhome water supplies are derived from drilled wells,the remainder primarily from dug wells. Springs,cisterns and surface water serve a very smallnumber of homes.
What is Groundwater?Groundwater is water that is found in pore spacesin the soil or in cracks or pores in the rock.Groundwater begins as rain or snowmelt(precipitation). This water can follow three mainpaths: Some evaporates from the ground and open
water surfaces, or is breathed out (transpired) byvegetation and returns to the atmosphere whereit can again form clouds, rain and snow andreplenish the earth.
Some runs off into streams or lakes or the ocean,called surface water runoff.
Some infiltrates into the ground. There, it followsvarious routes (flowpaths) and can discharge tothe ground surface as springs, discharge intosurface water, or recharge groundwater deeper inthe earth. As groundwater moves through theground, it dissolves some of the minerals that itcontacts. These dissolved minerals give water itschemical character or quality.
1Figure 1 The hydrologic cycle, or water cycle. This cycle involves the circulation of water between
land, atmosphere, and ocean.
How Does Groundwater Occur inNova Scotia?Groundwater is found in aquifers in the bedrock orin the material above the bedrock. An aquifer is awater-bearing permeable formation that will yieldwater in a usable quantity to a well.
How much water a drilled well yields depends onthe type of bedrock, type of overburden or surficialmaterial (the geologic material above the bedrock),well depth, and number of fractures (cracks) orpermeable layers encountered during drilling. Thebedrock aquifer generally consists of three mainrock types: igneous and metamorphic rocks such as slate,
quartzite and granite, which yield water mainlyfrom fractures
sedimentary rocks such as sandstone, shale andconglomerate, which yield water from spacesbetween the grains and from fractures
carbonate and evaporite rocks such as limestoneand gypsum, which yield water mainly fromfractures and cavities.
Figure 2 shows how these rock types are distributedin Nova Scotia.
In most places in Nova Scotia, the overburdenabove the bedrock is made up of glacial till, sandyto clayey in composition, depending on the natureof the local bedrock. Its thickness varies widely withlocation, but generally ranges from 0 to 10 metres(0 to 33 feet) and averages 6 m (20 ft). Dug wellsobtain water from this material or from the contactzone between the surficial material and upperweathered bedrock. Because till is generally low inwater yield, dug wells are usually constructed of90 cm (3 foot) diameter crocks that can store largeamounts of water.
In some places, the overburden consists ofpermeable sand and gravel deposits that aresaturated with water. Here, dug wells or screeneddrilled wells may produce relatively good yields.Such deposits occur along some of the major riversystems, the most extensive on the mainland beingin the Annapolis and Musquodoboit Valleys.
2Figure 2 Groundwater Regions of Nova Scotia (Simplified from Water Resources Map, NSDOE, 1985)
Planning a Water SupplyBefore you build your house or drill or dig your well,plan your water supply: a house is worth littlewithout an adequate supply of good-quality water,which may be found where you had hoped to placethe front steps!
To plan your water supply, find out what type ofmaterial lies under the ground, how much water youwill need, and where the well should be constructedto provide the best water supplyand meet regulations.
Why Should I Have a Water WellConstructed Before I Build?When you drill a well, you are actually exploring todetermine the quantity and quality of wateravailable. Totally dry holes are uncommon, but low-yielding wells are more common than you mayrealize. Some causes of low yield include low naturalor seasonal water table, interference with other wells(for example in subdivisions), and geologicconditions, as shown in Figure 3. In addition, goodquality water may be difficult to obtain in some areasdue to natural causes such as salt deposits and
closeness to the ocean. Occasionallyproblems may arise with well construction,as shown in Figure 4.
If problems arise, the cost to repair them isless if you construct the well first, becauseonly the cost of the well is involved. Also, if
a second well must be dug or drilled, there is morelikely to be sufficient space on the property if thehouse is not already there. Too many homes haveinadequate water supplies because the propertyowner did not have a well constructed before thehome was built.
Have the wellconstructed before
Figure 3 Dry Shallow Wells in Subdivisions
4An expensive house with a poor well is a poorinvestment; resale value will be lower. It may be verycostly to ensure an adequate supply of good-qualitywater. It is better to have a well constructed andassess the quantity and quality of the water supplybefore you build a house. Also, in areas where ausable water supply from drilled wells isquestionable, it is better to obtain an option on theproperty with permission to have a well constructedfirst. Following such a procedure may save you froma bad investment.
Where Do I Obtain BackgroundInformation for My Area?The type of material beneath the ground surface inyour area (geology) can tell you how successful youmay be in obtaining a suitable water supply from awell. In many areas of the province, groundwaterconditions have been examined and information canbe obtained from local well contractors, the nearestDepartment of Environment and Labour RegionalOffice (listed on page 33 of this booklet), andneighbours.
Local well contractors. Drawing on theirexperience in the area, contractors can su