I tried using the same "tap water conditioner" that I use for our aquarium (neutralises chlorine and chloramine, and bonds things like heavy metals). Even in a lower dose the snakes seem to avoid the treated water, so since then I've been standing a bottle of water to evaporate the chlorine - when I got the fish is checked to see whether chloramine is used here and it isn't. From what I read on the aquatic websites, water quality in the UK is less of a problem than it is in the US where water supplies are more fragmented.

Kat - does the filter strip out the chlorine? Sounds like it could be worth checking, although when I looked at water filters the running costs wasn't much less than cheap bottled water.