I would put one probe in the water, and one to the grounded hole of an outlet. Then I'd move the probe to the common wire. Your meter should be on 120v.
This is one of those tests where you want to be very careful what you are doing, and don't do it barefoot on a concrete floor. If the needle or the digital readout indcates anything more than 0, there may be a problem.
The stuff you are reporting all at once make me think of stray voltage. A seahare that is white, a naso that doesn't eat, and the LPS closed up - too many coincidences.