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Rainwater Harvesting: Design, Calculator and How To Build It Yourself

Discussion in 'Preparedness & Survival' started by Colt Carbine, Feb 24, 2012.

  1. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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  2. moose

    moose northwet coast Well-Known Member

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    Don't know about Oregon but at least its legal in Wa now to collect rainwater.

     
  3. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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    Yes sir. It is legal to do in Oregon and does not require a Water Rights permit.

    Link to Oregon's Water Rights: Water Resources Department Oregon Water Laws

    Some uses of water are exempt from the requirement to obtain a permit. These are called “exempt uses.”

    Exempt uses of surface water include:


    1. Natural springs: use of a spring that, under natural conditions, does not form a natural channel and flow off the property where it originates at any time of the year.

    2. Stock watering: where stock drink directly from a surface water source and there is no diversion or other modification to the source. Also, use of water for stock watering from a permitted reservoir to a tank or trough, and, under certain conditions, use of water piped from a surface source to an off-stream livestock watering tank or trough.

    3. Salmon: egg incubation projects under the Salmon and Trout Enhancement Program (STEP) are exempt. Also, water used for fish screens, fishways, and bypass structures.

    4. Fire control: the withdrawal of water for emergency fire fighting or certain non-emergency fire fighting training.

    5. Forest management: certain activities such as slash burning and mixing pesticides. To be eligible, a user must notify the Department and the Oregon Department of Fish and Wildlife and must comply with any restrictions imposed by the Department relating to the source of water that may be used.

    6. Certain land management practices: where water use is not the primary intended activity.

    7. Rainwater: collection and use of rainwater from an artificial impervious surface (like a parking lot or a building’s roof).
     
  4. billcoe

    billcoe PDX Platinum Supporter Platinum Supporter

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    Great links! Whats been holding me back is that we re-roofed with zinc impregnated shingles (to kill the moss).

    ...any idea what health effects that would have?
     
  5. Vantage

    Vantage Pacific Standard Time Active Member

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  6. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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  7. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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    As a plumber, I am not the expert on this. It is a good question and I will post information concerning this and everybody will have to come to their own conclusions based on the type of roofing materials and area that they live in.l
     
  8. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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    Safety of Rooftop/Rain Barrel Collected Water

    As rain barrels increase in popularity, questions about their use have arisen . . . Below is some information gathered from various credible sources (I neglected to ask permission to post their names):-

    Summary: The consensus is that there is not a clear consensus. There are significant and reasonable concerns about using rooftop harvested rainwater for drinking or watering food plants. To paraphrase a famous adage: Caution is the better part of good health.


    You'll have to weigh this information and should probably gather more before making your own choices and decisions. There are many variables to consider, including what part of the country you live in and what your roof is composed of. You can certainly have your water tested, though I suspect that is a costly procedure.

    [Note: If you can send or direct me to evidenced findings specifically about the use of rooftop harvested rain on edible plants by a credibile source, I would appreciate it.]

    From the Minneapolis Star Tribune Fixit column of 04/04/06:
    "...You can't drink the water collected, nor should you use it to water vegetable gardens. It's likely to be contaminated with chemicals and bacteria. But you can use it to water flower gardens and lawns or to wash lawn furniture, cars, etc...."

    From an Environmental Toxicologist with the Minnesota Department of Health (April 2006):
    Thank you for your inquiry concerning a warning you read in the newspaper about the use of collected rainwater for vegetable gardens. My search for data to back up the warnings turned up some useful information, but not all of the answers that you need.

    Rainwater washing off of roofs has been studied to determine the load of contaminants picked up from roofing material. Some rainwater collection systems, intended for drinking water, discard a first "flush" of water off the roof in order to make sure that organic material such as bird droppings do not contaminate collection tanks. The water is then treated for drinking.

    But the contaminants that you could be worried about are the heavy metals and polyaromatic hydrocarbons from asphalt shingles and other contaminants that may deposit onto roofs from air. It appears that contaminants that rainwater washes off of shingles may be a significant source of surface water contamination. The contaminants that are washing off of roofs include zinc, lead, chromium, arsenic, and polyaromatic hydrocarbons. It is similar to what you might collect off of a parking lot.

    It is possible to find data on the amount (concentrations) of chemicals in rainwater from asphalt roofs. However, I was not able to find information on whether or not the levels were high enough to accumulate in garden plants intended for consumption.

    I believe that warnings not to use roof-top collected rainwater for vegetable gardens are taking a precautionary approach. I do not know if the calculations have been made that would determine the extent to which these substances are accumulating in plants. Those calculations would need to be made before the MDH could tell you whether you could safely use the water for vegetable gardens.

    From another website: "When NOT to use a rain barrel for watering: If you have certain kinds of roofing material you shouldn't use rain barrels for watering plants. If your roof is made of wood shingles or shakes that have been treated with any chemical (usually chromated copper arsenate-CCA) to make them resistant to rot and moss, lichen and algae growth, don't water your plants from a rain barrel. Water collected from copper roofs or copper gutters also should not be used. Zinc (galvanized metal) anti-moss strips-usually mounted at the roof peak-also produce toxic chemicals you don't want in your garden. Don't use rain barrels if you have these strips (you may want to remove them), or if you have had your roof treated with moss-, lichen or algae-killing chemicals within the last several years. Note that nowadays there are asphalt shingles on the market which have zinc particles imbedded in the surface. Check your shingle specifications if you have recently re-roofed.

    In addition, general practice is to avoid watering vegetables and other edible plants, such as herbs you plan to use in cooking, with rain barrel water collected from asphalt-shingle roofs. These kinds of roofs may leach various complex hydrocarbon compounds, so most people avoid using water from asphalt-shingle roofs or flat tar roofs on plants meant for human consumption. To date there is no definitive research on the amounts and types of hydrocarbon compounds which may leach from such roofs, though it is common practice to use water collected from asphalt-shingle roofs for watering ornamental plants and shrubs. Enameled steel and glazed tile roofs generate little or no contamination and rainwater harvested from them is commonly used to water vegetables."

    From an urban rainwater collector and rainwater system designerwho works for the Council on the Environment of New York City (April 2006):
    The New York City Water Resources Group is in the process of having the collected rainwater tested at 1 site. Preliminary results show bacteria in the samples which is expected as we do not treat the water in any way. Also slightly elevated lead levels probably from airborne sources. No other contaninants that might be expected from roofing, piping or tanks. More testing will be done this season and hopefully a full report to follow. We have signage on the storage tanks warning not to drink.

    From someone at the Minnesota Pollution Control Agency (April 2006):
    I can kind of see the bacteria angle since maybe bacteria, fungus, etc. could multiply in a rain barrel, but the chemicals are the same ones that are already in the rain runoff. And bacteria levels in runoff, don't get me started. However, there are chemicals in tap water (like chlorine) and well water (like lime) that make rain barrel water preferable for gardens.

    Anyway, I think I would tell this person that a rain barrel is an excellent idea for the reasons that are listed in the Fixit column, but they should take the normal precautions in cleaning their veggies before eating them. You might also advise them to allow the spring rains to flush off the roof before setting up the barrel.

    I personally have two rain barrels and have no compunctions about using them for watering any plant, veggie or not. I did find (especially when we were heating with wood) that the first few flushes of rainwater from the roof in early spring had some soot and I wasn't comfortable using it for watering plants.

    From someone at the Pesticide and Fertilizer Management Division of the Minnesota Department of Agriculture (April 2006):
    Without water quality data I'm not sure what the basis is for these statements of risk. That said I don't think I would drink the water off an asphalt roof but concerns over using that water on vegetables seems questionable.

    From a University of Minnesota Horticultural Specialist (April 2006):
    [paraphrase] The advice of not using rain barrel water in vegetable gardens is sound and precautionary. Such water should not be used for drinking or for vegetables. Until a detailed study can be conducted, the best advice at this time is to use the water for ornamental landscape plants/lawns.

    Additional comment: I do not think there would be enough zinc or other metals in the collected rainwater to be toxic to plants. This is because any of these substances that may be present would be diluted substantially with the rainwater. The main concern with the collected rainwater is if applied to edible plants, there could be negative effects to humans if those plants are ingested. This would be due to accumulation of metals in the plant tissue over time. More importantly, if there are bacteria (E. coli) in the water and then sprayed on edible plant parts, this could also cause human sickness if the plants are eaten.

    More from an Environmental Toxicologist with the Minnesota Department of Health (April 2006):
    I spoke with a stormwater expert from the Minnesota Pollution Control Agency about your question. He, in turn, sent out a request for input to a national and international list serve. He sent some interesting comments back to me today.

    From the University of Connecticut: "Based on monitoring at a site with asphalt shingles in CT, we found very low (mostly ND) concentrations of Cu,Pb, and Zn in runoff from the roof. The roof did not have lead flashing, though. We did not test for mercury"

    From Snohomish County government, Washington: "Galvanized or copper flashing on asphalt shingle roofs should be a concern also. Here in the Pacific Northwest, where moss grows on nearly everything that's not moving, it's somewhat common to place a galvanized ridge cap on gable-roofed houses with cedar shake roofs. Minute amounts of zinc from the cap wash down the roof surface in rain and prevent moss from growing on the shakes. Without the caps moss grows thick on shake roofs here. I assume that if runoff from a 3-inch wide galvanized flashing is toxic enough to kill moss on an entire roof, it could be affecting other plants as well."

    From Volusia County government, Florida: "The adhesive for shingles is now including parts washer solvents. I understand a waste company in Florida picks up the parts washer fluid, ships it elsewhere and then uses it as part of the adhesive for shingles. I am unsure if the company removes the heavy metals, therefore, I would not use the rain water from the shingled roof-but that is my personal opinion."

    I hope that this is helpful. The consensus from web sites and these interactions seems to be that unless the roof is designed with materials and methods intended for rainwater collection, there is a possibility that toxic substances will end up in the water. The point made about the rainwater being toxic enough to kill moss and mildew suggests that it may actually be toxic to garden vegetables if collected water is a primary source of water for a garden.

    From a Physician with the California Public Health Service (March 2009):
    1) In California (and probably across the nation), rooftops are often sites for raccoon latrines. Raccoons leave feces on rooftops, usually where valleys form, or alongside the intersection of walls and roofs. The danger is the Raccoon roundworm (Baylisascaris procyonis), which is a common intestinal parasite in the raccoon. The roundworm eggs are found in the raccoon feces and the eggs develop in the feces -- often surviving for over a year in dried raccoon feces. These roundworm eggs can be found in roof runoff water; an internet search on "raccoon latrines" will give several references.

    2) Many shingles are now made with a mild algicide and/or fungicide. Usually this is a copper compound, but may be a more complex chemical.

    Filter The Water
    If you are concerned about contaminants in your rooftop-collected water, you can build a device to filter water. Visit this website to see one person's project creating a homemade bio-sand filter. (I can't vouch for how "clean" or safe the resulting water is.)
     
  9. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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  10. billcoe

    billcoe PDX Platinum Supporter Platinum Supporter

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    Thanks for that info OP. I think I might set up a single barrel for any potential crisis (I forget to rotate water I store in the basement), so it's htere in an emergency, but not use it to water the garden or plants.

    I thought this was interesting and probably fallacious:
    I wonder if they realize or have evaluated the idea that millions and millions of homes have people who are utilizing copper for supply lines: and unlike the roof system where the water is transitory, the water in the houses copper supply lines can stay in there for a long long time until it's used.
     
  11. powersbj

    powersbj Seattle Area Active Member

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    you only use one type of copper line for supply, also you make sure to use a lead free solder... Who knows what they use on gutters?
     
  12. Trainman82

    Trainman82 Salem, OR New Member

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    I have two 55 gallon barrels set up. Its just for emergency purposes. I'm also gonna use it to water my house plants. I guess I'll see if my plants die. My roof is covered by asphalt shingles, none of the anti-moss strips as there are no trees taller than my roof. Its handy to know I'll have water for cleaning and flushing my toilets and in an extreme situation drinking, after filtering and boiling. For the amount of water it keeps, its very cost effective.
     
  13. Colt Carbine

    Colt Carbine Oregon Gears-N-Guns

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    Regular copper flashing is 99.9% copper. Maybe they make other types besides the lead coated copper flashings but those are the two that I am aware of. Lead coated flashings would be pretty apparent, since it is coated with lead. Copper flashings are soldered with lead solder, so to cover their butts they have to mention the lead would be my guess.

    What they do not mention is that to this day chrome plated faucets are made with 3%-8% lead.
    So you bring up a good point about transitory contact with lead.

    As you mention the water that comes off the roof is transitory versus sitting in pipes. I am pretty certain there are many houses still to this day with copper tubing that was soldered with lead. Most people that still have copper piping with lead solder joints will let the water run for awhile to flush any water that may been contaminated with lead from sitting in the pipes. It is recommended that water sitting stagnant for more than 6 hrs. be flushed. Also hot water is more prone to dissolving lead than cold water.

    Everybody will have to make up their own mind on how they feel about health effects of lead and water. I will not give any advice on that.

    How Can You Treat Water To Remove Lead?

    There are simple steps you can take if you suspect lead contamination or if testing shows that flushing the tap reduces lead levels.

    Flush the water taps or faucets. Do not drink water that has been sitting in the plumbing lines for more than six hours. The longer that water sits in pipes, the greater the exposure to lead and possible contamination. Before using water for drinking or cooking, run the cold water faucet for two to three minutes, until you can feel that water has become as cold as it can get. You should do this for each drinking water faucet. Allowing the water to run an extra 15 seconds after it feels cold should flush the service connector as well.

    Use only cold water for cooking and dnnking. Hot water dissolves lead more quickly than cold water. Using cold water is especially important if you are preparing baby formula. Heat the water you need for formula on the stove or in the microwave oven. (Do not mix the water with formula or baby food and then heat it in the microwave. Uneven heating could result in "hot spots" that could burn baby's mouth.)

    Use bottled or distilled water. This water can be used for drinking and cooking if flushing the taps does not lower lead levels, or if your home has lead pipes.

    Treat well water to make it less corrosive.

    If you are building a home, state in writing that only lead-free materials are to be used for plumbing installation.

    Use lead-free materials when repairing plumbing or remodeling.

    Do Filters Reduce Lead Levels?


    Calcite filters can be installed between the faucet and any lead service connectors or lead-soldered pipes. Point-of-use filters like reverse osmosis and distillation units can also be used. They must be maintained to be effective. Activated carbon filters, sand filters, and cartridge or microfilter filters do NOT reduce lead levels, according to the EPA. When lead is a problem, water softeners should not be connected to pipes leading to drinking water taps.
     
  14. Vantage

    Vantage Pacific Standard Time Active Member

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    ALL the water we drink is rainwater. And most of it runs off roofs, it's just a matter of how it's treated before it gets to us to drink.

    You can't treat water you don't have. so yes... collect it, and treat it before you drink it.
     
  15. loucfir

    loucfir Pacific Northwest Active Member

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    Picked up 3, 1500 gallon poly tanks from a concrete producer they had taken out of service. They had held some chemical, wood based product, safe for human consumption they used in concrete production..looked it up on producers web site and found that out! Tied the three together and buried them down the hill below my home and garage and harvest all the roof water.
    The tanks bases have multipurpose discharge valves and large fill lids for adding pumps and overflow hoses. I use these all summer for water in my drip irrigation system in garden and orchard. Yes, it is now potable!!!