I used a Bilge Buddy switch for several years on our last boat. We never had
any problems with it, just wipe off the prongs every other month or so. Very
reliable. I did not know that they were still manufactured or I would have put
on on our new boat.
Mike
SV Slacker
GS 37

I've got a couple of Jabsco switches that rely on air pressure
increasing in a tube - the electrics can be mounted well away from the
water. Don't know how they work yet - but I was planning on using them
for shower emptying.