# Leaky backflow preventer



## jlegs80 (Mar 25, 2020)

Have a small leak coming out of the top of my backflow preventer. I just replaced the bonnet and o-ring. But it seems to ooze out still. Any idea what could be causing it? Would plumber's grease or silicon help create a better seal on the inside?


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## mattw10517 (Oct 22, 2017)

Did you get this fixed? I had a similar issue and had to add an extra o-ring to the top of the bonnet to improve the seal.


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## massgrass (Aug 17, 2017)

I dealt with a similar problem with my old Watts backflow device for several seasons. Initially, I had to clean mineral deposits off of the vent float and vent spring to get a good seal. I also found it useful to leave the valve between the backflow device and the sprinkler system closed when I initially opened the other valve between the water supply and the backflow device.

But after about 15 years I just swapped it out because I couldn't get it to stop leaking anymore, although I am considering rebuilding my existing one with the Watts 0887726 rebuild kit in a couple of years to avoid having the same problem.


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