Reduced pressure backflow preventer ?

[slharder]

A dumb question about a rp backflow preventer.

When the preventer "purges" to the funnel cup drain -- is it purging water from the supply side of the preventer -- or is it purging water from the house side of the preventer?

Just trying to determine how much water would be purged if the preventer trips.

 

[johnjh2o]

It's coming from the supply side. It can come from the house side if there is a drop in pressure on the supply side and the #2 check fails.

John