Rainwater Harvesting Mike Kizer OSU Extension Ag. Engineer

1. Gutter Downspout Rainwater Harvesting Mike Kizer OSU Extension Ag. Engineer

2. Rainwater Collection Issues • How much rainfall can I expect? • Annual total • Seasonal distribution • How much rainwater can I collect? • Collection area • Storage • How much water do I need? • Household use • Irrigation • Livestock

3. Oklahoma Annual Precipitation (30-year Average: 1971-2000)

4. Oklahoma Precipitation What is Normal? OCS 1990 Annual Summary

5. Oklahoma Rainfall What is Normal? 1998 Annual Percentage of Normal Precipitation OCS 1998 Annual Summary

6. OK Monthly Rainfall Distribution

7. Rainwater Volume Volume of water collected = L x W x D 12 x 12 x 1 = 144 in3 1 gallon = 231 in3 1 in rain = 144/231= 0.62 gallons / square foot of roof Not all will make it into the rain barrel ( 70%) D= rainfall depth (1 in) W= catchment width (12 in) L= catchment length (12 in)

8. Roof Catchment Area USE THE VERTICAL PROJECTION OF THE EAVE LINE, NOT THE SLOPED ROOF AREA SQUARE FOOTAGE BASED ON THESE MEASUREMENTS

10. Roof Catchments- Potable Water • Preferred Materials • Steel (galvanized, painted) • Tile (clay, cement) • Wood (untreated) • Fiberglass • Composition • Undesirable Materials • Tar • Asbestos

11. Rainwater Conveyance Structures(from Sustainable Building Sourcebook) • Slope gutters 0.5% (1 in/16 ft) • Place gutter hangers 3 ft on center • Use expansion joints in gutters 60 ft or longer • 1 downspout per 50 ft of gutter length • 1 in2 of downspout area per 100 ft2 of roof area • Slope horizontal conveyance pipes 2% (1 in/4 ft) • Horizontal conveyance pipes should have cleanouts every 100 ft • Limit horizontal conveyance pipe bends to 45º

12. Proper Rain Gutter Slope 16’ Long Level Line 1” Fall

13. Spacing of Gutter Hangars 3 ft

14. Roof Area & Downspout Size 32 ft 12 ft 1 square inch of downspout cross-section for every 100 square feet of roof area 32 ft x 12 ft = 384 ft2/100 = 4 in2 2 in x 3 in minimum size

15. Gutter Guard to Remove Roof Debris Slide This Side Under Shingles Clip This Side to Gutter ¼ to ½-inch wire mesh

16. Roof Washing Before Filling Storage Tanks Overflow hose 2-4 ft above downspout end with small weep hole allows initial runoff and sediment to collect in bottom of downspout. After initial washing period, cleaner water overflows into collection tank. Manually operated diverter allows initial rainfall to be wasted while roof is being washed free of sediment.

17. Roof Washer

18. Roof Washer

19. Roof Washer

20. Roof Washer

21. Roof Washer

22. Rainwater Storage(from Sustainable Building Sourcebook) • Cisterns may be above or below ground • Preferred materials: concrete, steel, fiberglass • Smooth interior surfaces preferred • Use water-tight, non-toxic joint sealant • Cover to prevent mosquito and algae growth • Manholes should be 24 inches wide • Buried cistern manholes should 8 inches or more above original ground surface

23. Large Capacity Above-Ground Cisterns

24. Small Capacity Above-Ground Tanks New 50-60 gallon Rain Barrels (2009 Prices) Plastic: $100-150 Oak: $350-300 Recycled barrels Food-grade polyethylene Oak New polypropylene rain storage barrels

25. Household Water Requirements Typical Usage: 50-100 gallons/person-day • Toilets: 0.6-1.6 gallons/flush • Washing Machine: 30-50 gallons/load • Dishwasher: 7-15 gallons/load • Bathtub: 30-50 gallons/use • Shower: 2.5-3.0 gallons/minute • Kitchen/Bath Sinks: 1.0-1.5 gallons/minute

26. Summer Irrigation Water Requirements(Adequate for flowers & vegetable garden) • Eastern OK: 0.20-0.25 inch/day (20 gallons/100 sq. ft.-day) • Western OK: 0.25-0.30 inch/day (25 gallons/100 sq. ft.-day) • The storage volume required makes rainwater irrigation makes impractical for large, water-intense landscapes

27. Livestock Water Requirements • Beef Cattle: 8-12 gallons/head-day • Beef Calves: 1-1.5 gallons/100 lb-day • Horses: 12 gallons/head-day • Sheep & Goats: 2 gallons/head-day • Chickens: 9 gallons/100 head-day

28. Appropriate Pipe Sizing

29. Units Conversions • 1 acre-inch = 27,154 gallons • 1 cubic foot = 7.48 gallons • 1 cubic foot of water = 62.4 pounds • 1 gallon of water = 8.34 pounds

30. Rainwater Harvesting Information Green Building Program: Sustainable Building Sourcebook www.greenbuilder.com/sourcebook/Rainwater.html Texas A&M Rainwater Harvesting Site http://rainwaterharvesting.tamu.edu/

31. Oklahoma Annual Precipitation (30-year Average: 1961-1990)

32. Pressure Requirements • 0.43 psi for every 1 foot of vertical lift • 10-15 psi for point-source drip emitters • 6-12 psi for drip tape • 30-50 psi for impact and rotor sprinklers • 20-40 psi for spray head sprinklers • 0.5-1.0 psi/100 feet of PVC/PE supply line

33. Water Pumps Little Giant 5/8 hp, 115 v. Submersible Pump Price: $195 (Plumbingstore.com) 13 psi Max. Pressure 22gpm @ 10 psi Dayton 1/3 hp, 115 v. Centrifugal Pump Price: $238 (Grainger.com) 18 psi Max. Pressure 10 gpm@ 15 psi

34. Rainwater Collection(Irrigation) • Waste initial runoff to wash off sediment • Screen organic matter (leaves) to prevent fermentation

35. Rainwater Collection(Drinking Water) • Waste initial runoff to wash off sediment • Screen organic matter (leaves) to prevent fermentation and disinfection by-products • Filtration by coarse sand recommended • Disinfection by chlorination, ozonation, or ultraviolet light is necessary

36. Net Irrigation Water Requirement

38. Homemade Roof Washer

39. Water Metering Household water meters 5/8-inch meter: Approx. $110 ¼- gpm – 20 gpm capacity Auto shut-off meter 100-1600 gallons Approx. $25

40. Large Capacity Below-Ground Tank (2009 Prices) 600 gal: $598 1700 gal: $1313 2500 gal: $2361

41. Circular Tank Capacity(Tank Dimensions: feet – Capacity: gallons)

42. Square Tank Capacity(Tank Dimensions: feet – Capacity: gallons)

45. http://www.twdb.state.tx.us/publications/reports/RainwaterHarvestingManual_3rdedition.pdfhttp://www.twdb.state.tx.us/publications/reports/RainwaterHarvestingManual_3rdedition.pdf

47. Annual Rainfall