Need some gutter/irrigation advice....

Discussion in 'Irrigation' started by thepawnshop, Dec 17, 2006.

  1. thepawnshop

    thepawnshop LawnSite Senior Member
    Messages: 387

    I am building a home that I hope to add a large plastic underground water storage tank that has the gutters from the house flowing into so as to "recycle" the rainwater for an irrigation system. My concern right now is that I prep properly for this project. THere is approximately 3500 square foot of roofing and I will be using 6" gutters (it is a combination of 10/12 & 12/12 pitches on the roof)

    What type of pipe should I use? I have ruled out the cheap black pipe but was wondering if I shoud rough it in with 4" schedule 40 or should I use green sewer line pipe? Also, where can I find the quality connectors to attach the gutters to the pipe? And finally, we are looking at a total of 8 downspouts...should I have them all feed into a single 6" pipe or multiples?

    For the time being, I plan on running them (all the pipes to daylight, but in the general vicinity of where I plan on adding the storage tank to later. If you guys have any websites I can check out for advice on how to properly plan this I would be VERY grateful as well.
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    I would use 4" 3034 (the green sewer pipe).

    You can get fittings to adapt from square downspout to either gasketed or slip (glue) for the 3034.

    You should be fine with a single 4" line around the perimeter, this is good for several hundred GPM, so you won't max it out unless you had a monsoon :)
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,758

    I would consider bumping up the size, given the total 'footprint' of the home and roof. Drains aren't allowed the same sort of flow restriction that pressure piping can have. (this can be worked as a sort of roof-drain question, which would give an idea of the amount of the water storage needed)

    One consideration with any water storage facility (besides the safety factors) is the prevention of mosquito access - there are rules about this stuff, now that West Nile and other forms of encephalitis are in the picture.
  4. thepawnshop

    thepawnshop LawnSite Senior Member
    Messages: 387

    the storage is below ground in a 2000 gallon plastic tank, so I don't think mosquitoes should be an issue.
  5. Mjtrole

    Mjtrole LawnSite Member
    Messages: 226

    Couple things you might want to consider:

    Your going to be collecting HUGE amounts of water if you get a steady rain for a couple days, you might need an overflow that dumps into a sewer system and may cause problems with the local builing departments.

    according to this: - Calculations Sample.doc

    Your going to be collecting over 6000 gallons of water per 3inches of rain, that's a huuuuge tank your going to need.
  6. thepawnshop

    thepawnshop LawnSite Senior Member
    Messages: 387

    AWESOME article. Quite eye opening. I may need some assistance in the design, but the most important aspect right now is the rough in phase which will for the time being allow for adequate rainwater removal from around the house.
  7. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,758

    2000 gallons is a mere pittance, when it comes to irrigation. One acre of lawn will drink up over a dozen times that amount in a week.
  8. thepawnshop

    thepawnshop LawnSite Senior Member
    Messages: 387

    So what size tank would you recommend?
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,758

    I don't recommend the entire concept. Not for lawn irrigation. Rainwater cisterns have been around for a very long time, but for the much smaller needs inside a household. If you had a full acre of lawn to water, at the rate of one inch a week, and then assumed you would supply twenty-six weeks of water in a year, you arrive at 700 thousand gallons, and would be digging a reservoir. For the money, you do better by drilling a well.
  10. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    I'm with you Boots. The whole cistern idea really can't sufficiently water any great degree of landscaping. I'm not saying it can't work but all the factors have to be just right; rainfall amount, rainfall timing, cistern size, distribution system, etc. It seems to me that it would be supplemental at best.

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