# Clicking sound in irrigation pipe inside house around where the backflow preventer feeds



## mot359 (Sep 28, 2019)

I recently swapped my pop up spray heads with mp rotators. They work well, but I notice a clicking sound inside when I turn them on. It seems to stop if I have flush nozzle attached to one of the sprinklers in the zone so I'm guessing it is pressure related? My other that I switched to mp rotators from rotors/pop up sprays don't have this issue.

Also, I recently fixed a 1 inch poly pipe in this zone which I noticed was 1 inch poly pipe adapted to a 1/2 inch Rain Bird swing pipe to another 1 inch poly pipe (I have no idea why). I patched it with a new swing pipe since it started leaking out of one end, but I don't think this was done correctly? It seems like someone repaired it incorrectly at some point and maybe that awkward spot is causing issues and the constant leaks I'm getting in this zone around swing pipes.


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## hsvtoolfool (Jul 23, 2018)

How loud are the "clicks"? Are they always the same? Are the clicks random (like microwave popcorn) or is there a regular pattern?

Since the noise happens when the valve opens, I don't think this is water hammer. My best guess is that your heads don't have check-valves. If so, the pipes may drain after the valve closes. When the valve opens the next time, water rushes into the pipes. This makes some noise as the air is forced out. The vibrations may be carried back via the pipes. Or perhaps the pressure changes cause the backflow preventer to activate and the clicks are coming from that device.


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## mot359 (Sep 28, 2019)

hsvtoolfool said:


> How loud are the "clicks"? Are they always the same? Are the clicks random (like microwave popcorn) or is there a regular pattern?
> 
> Since the noise happens when the valve opens, I don't think this is water hammer. My best guess is that your heads don't have check-valves. If so, the pipes may drain after the valve closes. When the valve opens the next time, water rushes into the pipes. This makes some noise as the air is forced out. The vibrations may be carried back via the pipes. Or perhaps the pressure changes cause the backflow preventer to activate and the clicks are coming from that device.


Consistent random clicking like popcorn sounds right. I use the PRS40 bases from Hunter and haven't noticed this before the pipe repair. Maybe air got in and stuck and I just need to do a really good flush with the flush caps?


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## hsvtoolfool (Jul 23, 2018)

Sounds good.


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## mot359 (Sep 28, 2019)

That fixed it! I guess I didn't leave it on long enough when trying that yesterday or didn't use flush nozzles on enough heads (used on last three in zone instead of just the last one this time).


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