Sam Angima & Bill Biernacki

Introduction Rain water is (if collected

from tin roofs)

Pure

Soft

Neutral pH

Salts

Minerals

& other man-made products

Introduction Rain water is

Free (cost = collection and use)

No costly distribution costs

Flushes salts off garden soils

Reduces flow of storm waters

Reduces your water bills

What is Rain Water Harvesting? Rainwater harvesting is

the capture, diversion, and storage of rainwater for a number of different purposes including

landscape irrigation, drinking and domestic use, aquifer recharge, and storm water abatement.

How Much Water Can You Capture? About 0.62 gallons/sq ft of surface per 1-inch of rain

Potentially, for our av. 100 inch rainfall/year, one sq ft roof will collect 62 gallons per year

Of this, assume 75 % collection efficiency (47 gal/yr)

Then find how much water you need (~ 3 months period) and how much you need to collect

How do you calculate roof area for different roof styles?

Catchment Areas of Three roof Styles

Components of RWHS Catchment surface (usually a roof)

Gutters and downspouts

Leaf screens

First flush diverter (plus filtration)

Removes debris and dust before going to tank

Storage tanks (cisterns)

Delivery system

Gravity fed or pumped

Treatment or purification if needed

The Catchment Surface Usually roof

Metal: commonly Galvalume 55% aluminum & 45% alloy coated steel sheet.

Clay/concrete tiles: have ~10% loss due to texture

Composite or asphalt shingles: most common

They leach toxin do not use for potable water systems

Good for irrigation water gardens

10% loss of water compared to metals roofs

Wood shingles, tar, gravel: use only for irrigation

Gutters and Downspouts

Capture rain water running off eaves of building

Drop outlets

downspouts

Leaf Screens Remove debris to get high quality water

Mess screens work well need to be cleaned regularly

Or leaf screens inch mesh screens

Funnel-type downspout filter: easy accessibility for cleanup

Strainer baskets slip into drop outlet of downspout

First Flush Diverters

Routes first flow of water away from storage tank dust, pollen, bird & rodent feces.

Simplest is a PVC stand pipe

Drains continuously via pinhole

One rule of thumb for first-flush diversion is to divert a minimum of 10 gallons for every 1,000 square feet of collection surface

OR always turn of collection system during first rainfall event to wash the roof

How Long Should The Standpipe Be?

If using

3 diameter PVC, allow 33 length of pipe/gallon

4 diameter pipe allow 18 of length/gallon

6 diameter pipe, allow 8 length/gallon

Roof Washers Pre-filters water before

storage

Especially for drip irrigation

Filter is usually 30-micrometer pores about of human hair

Storage Tanks Many types

Must be opaque to discourage algae formation

Have not contained toxic chemicals

Must be vented and screened bugs/mosquitoes

Cleanable

Have an overflow that does not run into septic system drainfields

Stable ground

Water weighs 8 lbs/gallon

So a 1500 tank will weigh over 6 tons full

1. Fiberglass Tanks (50-15,000 gallons)

2. Polypropylene (plastic) 50-10,000gallons

Metal Galvanized

Concrete Tanks

Rain BarrelsFood-Grade Plastic Barrels

Gravity or Pump? You need at least 20 psi for sprinkler irrigation of your

lawn/garden

Water gains 1 psi of pressure for every 2.31 feet of vertical rise

So to get 20 psi you need 43 feet of drop or just use a pump

A solar panel & pump can run the system and pay back in time

You can add household laundry bleach to kill bacteria/algae at 1 oz per 500 gallons or 0.1 oz/barrel

Newport

Screens Help Reduce Roof

Dirt

Home-made Strainer/filter

Rain BarrelsFood-Grade Plastic Barrels

Water Rules

Dirty Water

Newport