Hills and backflow preventers.

Discussion in 'Irrigation / Sprinkler Forum' started by drick, Jul 26, 2010.

  1. drick

    drick In the Trades

    Messages:
    392
    I have a 7 foot hill that rises up behind my house. I will be landscaping it soon and I'd like to add sprinklers. I already have an irrigation system for my front yard and would like to tap into it. Can I use my existing backflow preventer which is essentially at the bottom of the hill? Or do I have to pipe the water to the top of the hill, install the backflow preventer there, and then go out to my zones on the hill?

    I recall reading somewhere that the backflow preventer has to be at the highest spot in your irrigation system, but now I can't seem to find that reference.

    -rick
  2. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,298
    Location:
    Yakima WA
    There are several different kinds of BFP. Some do have to be at the highest point in the system, but better ones (also more expensive) do not. You should check with your city to see what their requirements are. I use a Wilkins Double Check BFP that is installed in a plastic box below grade. I am required to have it certified each year by a licensed inspector. All BFP should be inspected yearly because they do wear out and require repairs occasionally, but some communities ignore the EPA rules.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,249
    Location:
    Cave Creek, Arizona
    ALL backflow preventers SHOULD be installed above grade, if they have a "vent" on them. A backpressure on any, other than a RPPBFP version which can stand a 5# backpressure before venting, have to be above the highest point in the system, otherwise they "drain" out everytime the water is turned off, and theoretically could cause contamination of the potable water system. Most areas do NOT approve a simple "double check BFP" without a vent, since there is no indication when they fail or are failing.
  4. Fireguy97

    Fireguy97 Irrigation Contractor

    Again check with your municipality. Some areas approve a Pressure Vaccume Breaker (PVB), some don't because they don't handle back pressure, just back-siphonage.

    You don't mention where you are, do it's difficult to help any more.

    And by the way, a double check valve backflow assembly (DCVA) doesn't have a vent port. If it did, It wouldn't be a DCVA, it would be a reduced pressure principle backflow assembly (RPBA).

    Mick
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