In article ,
Alan writes:
In message , Bob Minchin
wrote

Infra red detector ones are best. They only switch on when a hand or
similar is in range.

But that implies some electronics - electronics and water don't mix to
give a long term reliable solution.

The ones I came across used 1 D-cell battery, which lasted
about 5 years (but not very heavily used - I think they were
supposed to last 1 year in heavy use). None of them ever broke
AFAIK, and they were probably 10 years old when I left that place.
Sorry, no idea what make they were.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]