We are doing a install right now that has two water sources. One is a 1 horse pump that is pumping non potable water from a irrigation feed. This is only on 4 months of the year, and the client wants to be able to water from her well when this line is off. Her well pump is smaller than the irrigation pump, so there will be issues on running it off that supply if we designed it for the irrigation pump, but if we design it for the well pump it will cycle the irrigation pump. My first thought was to use a pump start relay on the irrigation pump, and use the pressure switch/pressure tank setup on the well pump, and design for the well pump. The problem is that we are putting in a yard hydrant, so using a PSR won't work. The idea I have right now is to wire a PSR directly to the 24v output on the timer, and wire a flowswitch in series with the PSR. My thought is that if water is moving, the PSR will activate the irrigation pump, but if there is no flow, the PSR stays off. We'll use a backflow and isolation valve to keep the flow switch and non potable supply seperated from the domestic well supply. Can anyone see a flaw with this idea? Also, do they make a flowswitch that activates when there is flow, instead of one that closes when there is flow?