I'm working as a handyman for a non-profit, and they have an in-ground irrigation system that has been off for a while because "there was a geyser."

I successfully determined that the geyser was water shooting out of the top of the backflow preventer. It had blasted the bell off the top, destroying the guts of the poor thing.

Unfortunately, I'm very unfamiliar with in-ground irrigation systems (I didn't even know what a backflow preventer was until last week). So I'm concerned that if I rebuild the guts of the valve, it may also be destroyed by whatever caused the problem in the first place.

So what kinds of things do I need to check for to make sure that the new backflow preventer isn't similarly disemboweled? Is this just a thing that happens when they get old? Is there something else farther down in the system that is creating a bad situation?

My hope is that the original failed because it froze too hard, and this one will last so long as I can keep it from freezing. BUT we're in central Texas... it rarely freezes, let alone very hard.

  • Wow! What sort of supply pressure is coming in from the utility out where this happened? Jun 12, 2018 at 19:06
  • I have no idea, but it's a normal sort of municipal supply. I expect more or less typical?
    – mHurley
    Jun 12, 2018 at 19:34
  • Up where I live we get more snow and irrigation systems like this must be “winterized” (drained of all water, usually blasted with compressed air). If you did get a real freeze, that could certainly damage the back flow preventer.
    – auujay
    Jun 13, 2018 at 0:24
  • @mHurley -- if you could get a gauge on it, that'd be good. Jun 13, 2018 at 2:24
  • @ThreePhaseEel -- That's not a bad idea. I'll see what I can do.
    – mHurley
    Jun 13, 2018 at 14:02

1 Answer 1


The only way that could happen is if the nut was loose and then pressurized. Those BFPs are serviceable and the nut must have been left loose. If you can find the components from under the bell you can probably reuse them. Otherwise a replacement kit can be purchased. Before reusing anything make sure the threads were not stripped, possibly from over tightening. http://www.febcoonline.ca/Repair_Kits enter image description here

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