The CSV125 needs to be installed before the hydrant. It could go in the well or in place of the check valve. With that check valve before the hydrant it will still allow use of the hydrant. But the extra check valve is just a problem waiting to happen. If it is not already causing a water hammer on pump start it will cause that in a matter of time. Not only does the extra check valve cause water hammer on pump start, but it keeps the underground line at negative pressure, which can draw in contamination from the dirt and mud. The check valve needs to be removed, but I don't think it will have an effect on the CSV125 installed before the hydrant.
