I have an underground water tank (UWT) and an overhead water tank(OWT). The municipal water supply feeds into the UWT and a pump lifts water from the UWT to OWT. I can use a controller like this to automate turning on/off the pump based on water level in UWT and OWT so that assures there is no overflow and the pump never turns on dry.
However, I want to also be able to directly pump the municipal water to the OWT when available. Help appreciated.