With the latest firmwares for the Zooz Appliance switch (one of the few motor rated plug in modules) can disable both the physical and Zwave switches. (firmware 1.03 according to their documentation) They are fairly economical, especially when they go on sale, which they regularly do (and are now). You could monitor if the pump has run with "X" time period. This would work OK if it is a plug in type pump.
The other option might be to do this:
Suggestion for a device that senses voltage? Septic Tank Alert In particular, I outline using a relay starting at post 13 or so.
