Should I use a double check valve in my high-sand application

Discussion in 'Irrigation / Sprinkler Forum' started by ddinnsen, Sep 1, 2019.

  1. ddinnsen

    ddinnsen New Member

    Jul 10, 2014
    I'm currently irrigating with a web of hoses with anti-siphon bibs and Melnor 4-zone timers, but I'd like to get a "real" irrigation system. I have no issues with backflow now that I have noticed. I'm on a 15 gpm, 55 PSI well, but I use most of it for my geothermal heat pumps leaving about 7 GPM for irrigation. I also have lots of sand in the water. I initially installed the irrigation line after a 1" Lakos spin-down filter, but it clogged with sand before I could finish watering the yard. Now it is after the filter which means full sand, but it works great. I'm concerned that a double check valve will have problems with sand and also reduce pressure. I'm confident that if I added a strainer, it would clog too fast. I do not have any puddling at the heads and I don't use nasty chemicals on my lawn., but I do have sprinkler heads higher than my the tap for this 3/4" circuit. Recommendations?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    THey make special valves for in-ground sprinklers. If you were on a public water supply, in many places, you'd be required to have one, and some places require an annual inspection by a certified specialist...they take contamination of the public water supply seriously. To me, it makes sense to do that for my own home. I don't know if it's required where you live.
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  4. drick

    drick In the Trades

    May 16, 2008
    If you are planning on using rotors for irrigation I'd avoid the double check valve. If you had 80 PSI it wouldn't be a problem, but at 55 PSI you can't really afford to take the PSI hit. One way to avoid the double check valve would be to design your system so that you have a main line run to the highest point in your yard that will ever have a sprinkler head. Put your check valve here. All your sprinkler valves and sprinkler heads would then be installed after that check valve. Another way would be to do as jadnashua suggested and use sprinkler valves that include a built in check valve for only the zones that are higher than where you want to locate your check valve for the other zones. Generally these valves pricier and require installation higher than ground level so you will want to hide them. Your remaining zones will be protected using the check valve installed at your preferred location.

    While you can design an irrigation system to work with 7 GMP, it would be better if you could use the full 15 GMP that your pump can provide. Is there any way you can shut down the geothermal while you water? If you are installing rotors going below 2 GPM per head can be dicey. Also use 1" not 3/4".
  5. WorthFlorida

    WorthFlorida The wife is still training me.

    Oct 28, 2009
    Orlando, Florida
    Does the sand problem get worse when running the pump for long periods?
    To help reduce the sand problem, run the sprinklers twice a day to meet your watering needs. Such as 15 minutes per zone in the morning and then in the evening, 15 minutes per zone. Almost everyone overwaters their yard. If the sprinklers are layed out right 15-20 minutes of watering every two-three days is generally is sufficient with little or no run off and puddling.
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