Published on February 22, 2014
Catch the Rain with Jeremiah Kidd San Isidro Permaculture In an animal or plant, 99 molecules in 100 are water…An organism is a pool in a stream of water along which metabolites and energy moves through ecosystems. W.V. Macfarlane
Why catch rainwater? Primary Source Naturally distilled Saves energy and chemicals Recharge aquifer Reduce erosion and runoff Water security Human Impacts Institute. 2012
Why catch rainwater Store for dry season Multiple Uses Self Reliance Plants benefit Contains N and P Remote areas Free Conserves aquifers
Benefits to the Environment EPA ranks urban runoff and storm sewer discharge as second main source of water quality impairment in estuaries and fourth in our lakes James, William “Green roads: Research into Permeable Pavers” 2002 “…have shown that up to 70% of the pollution in our streams, rivers, and lakes is carried there by stormwater,” (Raingardens.org)
Benefits to the Environment “contributes to a yearly loss of rainwater infiltration ranging from 57 to 133 billion gallons. If managed on site, this rainwater—which could support annual household needs of 1.5 to 3.6 million people—would filter through the soil to recharge aquifers and increase underground flows to replenish rivers, streams, and lakes,” Paving our Way to Water Shortages (American Rivers, Natural Resources Defense Council 2002.
Misconceptions No recharge Too little Mosquitoes Deprives lakes Eyesore Too complicated/ expensive Must use tanks Bill Abell 2009
Physical Properties of Rain Water Water seeks the lowest point and path of least resistance Conserve energy by storing at highest point possible for pressure, .43 psi per 1’ elevation, 1 psi=2.31 feet of elevation One gallon of water weighs 8.3 lbs, 3.8 kg One liter of water weighs 2.2 lbs, 1 kg There is 7.48 gallons per cubic foot of water There is 1,000 liters per cubic meter of water Lower pH than groundwater in the arid areas
Qualities of Rain Water Precipitation is the primary source of fresh water within our planet’s hydrological cycle. Precipitation is naturally distilled through evaporation prior to cloud formation, and thus is one of our purest sources of water. Rain is considered soft due to the lack for calcium carbonate or magnesium in solution and is excellent for cooking, washing and saving energy. Rainwater is a natural fertilizer – picks up N & P Rainwater has the lowest salt content of natural fresh water sources so it is a superior water source for plants.
Water Harvesting Principals Begin with long and thoughtful observations. Start at the top (highpoint) of your watershed and work your way down. Start small and simple. Slow, spread, and infiltrate the flow of water. Brad Lancaster: www.harvestingrainwater.com
Water Harvesting Principals Always plan an overflow route, and manage that overflow as a resource. Maximize living and organic groundcover. Maximize beneficial relationships and efficiency by “stacking functions”. Continually reassess your system: the feedback loop. Brad Lancaster: www.harvestingrainwater.com
Design starts with observation What is the rainfall patterns: wet, dry seasons How much average rainfall in your area? Where are there catchment surfaces? What is the elevations of the catchment surfaces in relation to point of use? What is the vegetation growing above and below catchment surfaces? Taste and smell experience difference from city or well supply
Planning a water harvesting system 1. What will the water be used for? 2. How much rain falls in a year? 3. How much water is consumed? 4. The area of roof or other catchment available? 5. What size storage can be built? 6. Where to place the storage relative to the catchment and point of use. 7. Budget/resources available
Parts of a system Collection Surface – Roofs, Patios, etc Conveyance – Gutters, Downspouts, Piping Filtration – Screens, First Flush Storage Containers – Tanks, Ponds, Soil Other Parts – Pumps, Pressure Tanks Overflow – Rain Garden, Swales, Pond Water Usage – Domestic, Toilet, Irrigation
Preferable Surfaces Acceptable roofing materials are slate, terra-cotta tile, copper, untreated wood shingles, concrete, and metal painted with an epoxy paint. Unacceptable materials are asphalt shingles, older concrete tiles (which can contain asbestos), tar, or treated wood shingles. Asphalt shingles are by far the most common roofing material. Unfortunately, they leach toxins into the water that runs off them. If you have asphalt shingles, think of other options or apply acceptable surfaces on some or your home.
Conveyance Gutters, Downspouts, Piping
Roof to Tank
First Flush Examples Courtesy of HarvestH2O.com
First Flush Sizing 1-2 gallons per 100 sq. ft. of roof area. 5-10 gal per 1000 sq. ft. A 1’ length of 3 inch pipe holds approximately 0.74 gallons A 1’ length of 4 inch pipe holds approximately 1.30 gallons
Pre Tank Filtering
Storage Containers – Tanks
Water Wall Tank
Above Ground Tank
Partially Buried Poly Tank SIP 2011
Buried PE Tank SIP 2011
Linking Cisterns in Parallel
PE Tank in Parallel SIP 2011
Access Risers & Venting
Ferro-Cement Tank Uganda
Finished 79,800 liter Tank!
Post Installation Inspection
Monthly Precipitation Charleston, West Virginia Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Total: 3.00” 3.31” 3.91” 3.24” 4.80” 4.29” 4.94” 3.74” 3.25” 2.67” 3.73” 3.27” 44.15” The driest month is October with 2.67” of precipitation, and with 4.94” July is the wettest month.
Calculating Catchment Charleston, West Virginia Average Annual Rainfall ~ 44.15” Method 1: 1000 sq. foot house X 44.15” rainfall (average annual rainfall) / 12 (12 inches per cubic foot) = 3,679 cubic feet of water 3,679 (cubic feet) X 7.48 (7.48 gallons per cubic foot of water) = 27,519 gallons per year
Calculating Catchment Charleston, West Virginia Total Annual Rainfall ~ 44.15” Method 2: Catchment Area (square feet) X Average Rainfall (ft) X 7.48 (gallons per cubic foot) = Total Rainwater (gallons) 1,000 square feet X 3.679’ (44.15” / 12) X 7.48 (gallons per cubic foot) = 27,518.92 gallons per year
CATCHMENT AREA in squarefeet 28’x33’=924 f2 X RAINFALL 44.15” / feet = 3.8 f3 X 7.48 = 26,264 Gallons per year
Calculating Storage Charleston, West Virginia October 2.67” Average Rain Fall – Average Low. 1000 sq. foot house X 2.67” rainfall (average monthly rainfall) / 12 (12 inches per cubic foot) = 222.5 cubic feet of water 250 (cubic feet) X 7.48 (7.48 gallons per cubic foot of water) = 1,664.3 gallons in January 1,664.3 / 4 = 416 gallons per family member (family of 4) 416 / 30 (average days per month) = 13.9 gallons per day each
Calculating Storage Charleston, West Virginia July 4.95” Average Rain Fall – Average High. 1000 sq. foot house X 4.94” rainfall (average monthly rainfall) / 12 (12 inches per cubic foot) = 411.7 cubic feet of water 411.7 (cubic feet) X 7.48 (7.48 gallons per cubic foot of water) = 3,079.5 gallons in January 3,079.5 / 4 = 769.9 gallons per family member (family of 4) 769.9 / 30 (average days per month) = 25.7 gallons per day each
Calculating Storage Charleston, West Virginia Average Water Use in the USA Bath – A full tub is 36 gallons Shower – New heads 2 gallons per minute / 5 gallons with the old Brushing Teeth - < 1 gallon Washing Hands & Face – 1 gallon Face & Leg Shaving – 1 gallon Dishwasher – 4 – 10 gallons per load Dishwashing by Hand – 20 gallons Clothes Washing – 25 gallons per load Toilet Flushing – 1.6 – 3 gallons per flush Drinking Water – 8 – 24 8oz cups per day (1/8 – 3/8 gallon per day) *A Santa Fe Family Uses 23 gallons Per Person Per Day For the Household
Calculating Storage Charleston, West Virginia Potable water at 2 gallons per day for family of 4 is 240 gallons per month – a 500 gallon tank sufficient For whole house would suggest at least 2,ooo gallons – 67 gallon per day
Pumps: Choose the right one for the job
Pump Characteristics Water pumps are designed to push water not pull Whenever possible locate pumps so water flows into the pump by gravity - Foot Valve Suction Head is the pressure required to pull water into the pump housing, most pump not more than 10 feet Match needed flow rate with pump output GPM Sprinklers or flood irrigation uses much more GPM than Drip Irrigation Prescreen to 1/8” for inlet of pump
Pressure Tank or On Demand Pump Pressure tank keeps extra water available so small demands do not trigger pump start Prolongs the life of a pump by reducing on/off Provides water that is under pressure On Demand Pumps-cycles on/off as demand requires - Does not require a pressure tank - May have built in dry protection - Usually has shorter life
Pump Controls Floats for On, Off & Auto Filling Pressure Switches Irrigation Computer Smart Controllers
Gutters Materials - Vinyl, Aluminum, Steel, Stainless, Copper Slope – 1/16” per 1’ to 1/16” per 10’ Tilt Out – ½” to prevent water seeping into walls Expansion Joints for runs over 40’ Sufficient Support Downspouts – 1 per 1,000 sq ft surface 1 sq inch of outlet per 100 sq ft surface Screen to reduce debris entering conveyance Prune Branches Snow Cleats – reduce damage, increase catchment
On Ground Catchment Catch Boxes Drain Grates Patio Drains
Preventative Care & Health Risk Realities Keep vegetation and animal nests away from the catchment surface - First Flush Diverters Leaf Screens – make them accessible Good Things – Water improves with age –Biofilm Many people around the world live on rainwater. Dilution reduces load on immune system Simple & Economical Filters Available
Sanitation Be cautious but not paranoid, filter for needs Don’t clean your tanks unless emergency-Biofilm Pollutants that can be found in rainwater: Microbiological: Parasites, Bacteria, Fungi, Organic - Bird Droppings, Insects – UV Sterilization Chemical Contaminants: Volatile Organic Chemicals (VOCs) – Solvents – Carbon Filter Synthetic Organic Chemicals: Usually only around heavy industrial areas – Carbon Filter Minerals/Metals: Copper, Lead from roofs or gutters -
Sanitation: Microbes Viruses: smallest 20 to ~100 nanometers in size. Most difficult to remove Bacteria: larger (0.5 to 3 micrometers) also can not be removed by plain sedimentation or settling Protozoan: next largest (3 to 30 micrometers) largest ones likely to gravity settle at appreciable rates. Can filter out some waterborne pathogens are often associated with larger particles or they are aggregated (clumped). Aggregated or particleassociated microbes are easier to remove by physical processes Coagulation-flocculation WHO 2012
Treatment of Stored Rainwater If going to do it, do it right Chlorination Filters Boiling Sunlight Additional Treatments
Chlorination Effective, but conduct with care Shock with 1 Tablespoon (.5 ounce or 14g) swimming pool calcium hypochlorite (60-70%) per 530 gallons (2000 liters) Stir and let stand 24 hrs for chlorine to dissipate Maintain with 1/7th of the above amount - stir in and let stand 2 hrs Mix chlorine into water NOT water into chlorine webelements
Filters Sediment/Screen 80-100 micron Carbon – Best for VOC’s Whole house 10 micron can be found for $200 Ceramic – for smaller particles – viruses Reverse Osmosis (RO) Finest yet wastes 1-5 x filtered
Sand Filter “Biofilm” provides the effective purification in potable water treatment with 9099% bacterial reduction Courtesy of Clean Water for Haiti & National Drinking Water Clearing House
Filtration - Ceramic The Gravidyn is a microporous ceramic filter element with an inner core filled with activated carbon granulate. 99.9999 % removal of harmful Bacteria and Parasites 99.99 % removal of Cryptosporidium and Giardia General: Removal of organics (this will include: organic contaminants, pesticides, micropollutants, humic acids, detergents) and free chlorine Katadyn Ceramic Filtration System $295.00 - $318.00 www.katadyn.com
Sanitation Viruses: 99.999% reduction MS2 - Fr Coliphage*Exceeds purification standards Pathogenic Bacteria, Parasites, and Cysts 100% reductionE. coli, Klebsiellaterrigena, Pseudomonas aeruginosa, Giardia, Cryptosporidium*Exceeds purification standards Trihalomethanes: Removed to below detectable limits - 99.99999% reduction Bromodichloromethane, Bromofore, Chloroform, Dibromochloromethane Berkey Filtration System $228.00 - $625.00www.berkeyfilters.com
Sanitation Katadyn Hiking Carbon System $50.00 - $150.00
Boiling 2-3 minutes A lot of fuel Take a while to cool Not always feasible Solar Cookers Dr. Kundapur
Low-Tec Sedimentation Simple and low cost: storage vessels - pots, buckets Clays and smaller microbes do not settle Do not disturb sediment particles at bottom Unreliable to reduce pathogens Remove solids and clean regardless of storage vessel type Good pre-treatment to remove turbidity before UV or chemical disinfection
S.O.D.I.S. Solar Disinfection 6 hrs full sun – UV starilization
Sequence Combining Filtration and Purification Strategies for Potable Water
Sequence Combining Filtration and Purification Strategies for Potable Water
Corrosion Control pH Rainwater naturally Acidic: 4.5-6.3 – usually not a problem Affects Copper – raise with Baking Soda (sodium bicarbonate) periodically to pH of 7.4 In-line Filters Available – Calcium carbonate (limestone) pellets, Sodium oxide (lime) pellets – these must be downstream of UV units
Water Quality Enhancers Calmed Inlets – Minimize the disturbance of sediment on bottom of tank and Biofilm Floating Valve Out-take – Remove water from the “sweet spot” when possible
Thank You! Jeremiah Kidd San Isidro Permaculture firstname.lastname@example.org www.sipermaculture.com +1 (505) 983-3841
Thanks to Aaron Kauffman Brad Lancaster Chelsea Green Publishers John Gould & Erik Nissen - Peterson
Resources Rainwater Harvesting for Drylandswww.HarvestingRainwater.com Virginia Rainwater Catchment Manualhttp://www.cabellbrandcenter.org/Downloads/RWH_Manual2009.pdf Simple explanation and diagram http://www.chelseagreen.com/content/free-yourwater-fundamentals-of-a-rainwater-harvesting-system/ Supplier in Salem, Virginia http://rainwatermanagement.com Supplier in Maryland offers all parts needed for a systemhttp://www.conservationtechnology.com Supplier in Georgia http://www.rainharvest.com Contech Engineered Solutions 700 Tech Dr, Winchester, KYwww.conteches.com First Flush Design http://cals.arizona.edu/cochise/waterwise/first_flush_diverters.pdf
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