Scott I still do some "water testing" every day and find the taste test and the snail crushing test not to be very helpful - but I do find the soap/lather qualities of tap water to be a useful factor :-)
P. tenellus has been a very hardy and adaptable species for me once they have been successfully been transported home and settled in (very much like P. mellis) even though in all of the places I have caught them the water was very soft and acid.
Bruce Hansen