Should a backflow preventer be placed before or after the PRV?

[plasmech]

Should a backflow preventer be placed before (upstream) or after (downstream) of the PRV?

Thanks.

 

[Twowaxhack]

On home water mains in my area the backflow device is upstream of the pressure reducing valve. In my area the water company installs the backflow preventer on house mains. The plumber is responsible for reducing the pressure.

It would work either way depending on if your starting pressure is within spec of the backflow device

 

[MrInfoPhilly]

Not a code., but I'd prefer to install the PRV downstream of the back flow device., That way you have the maximum desired pressure after the double check valves which slightly reduces pressure. Also., if you need to replace or rebuild., easier to turn off from the check.

 

[plasmech]

Thanks. I guess it makes sense for the backflow preventer to be the first thing inside the house?

 

[MrInfoPhilly]

Thanks. I guess it makes sense for the backflow preventer to be the first thing inside the house?

It's truly a preference., but I laid Out why I prefer to put the backflow in first. Set the pressure after the restrictions. If you can., add a Gauge after the PRV to always see that the PRV is working.

 

[plasmech]

I wonder if I should just remove it. It's not doing anything for ME, right?

All it's doing is probably costing me 5 PSI.

 

[MrInfoPhilly]

I wonder if I should just remove it. It's not doing anything for ME, right?

All it's doing is probably costing me 5 PSI.

The backflow device may be required by your local code because of your irrigation or something you have installed. It prevents cross contamination in case of back flow down stream

 

[Geofd]

Thanks. I guess it makes sense for the backflow preventer to be the first thing inside the house?

Is the city or town requiring you to install a backflow preventer on your water main????
What's their reasoning????
You would only need a testable on on your irrigation that separates your irrigation from yourown water main