Agree with Lou. If you want that the relay itself changed position confirmation, go get a DPDT and use the second pole to monitor that position. But this will not tell you the 'actual' water valve status.
For true positioning as in a Process Control industrial sense, if that is desired, the hardware itself will have position indicators of the valve position. A lot of time this is needed especially when triggering pneumatic valves via a solenoid from a process control I/O module. In this case it is imperative to monitor the actual pneumatic valves position which is done via internal contacts that change depending on a full open or close. Usually the HMI is then designed with a logic block so it can display the command sent as well as if the valve is open, closed, or "traveling". If it did get stuck an alarm color would then be displayed on the valve (usually blinking yellow).
Additional monitoring is required on some items because it will also 'allow' an open or closed command only based on the original position of the item. This is true in contactors (large power switching) that have a latch and unlatch coils. They will also have a position monitor that is usually another pole, though not the size of the others as it is only for monitoring purposes only.
For other critical 'throw' functions that don't have onboard monitoring on the device, alternate methods are selected, such as current monitoring for a pump. Again, the HMi will display a current value usually right next to the command (on off) button.
This is why I suggested a flow monitor might be considered for your water valve situation if this was truly a critical function.
Many ways to skin this cat, all depending on hardware selection as well as how important (and cost justified) the need is.
