I struggle with water too. I bought something called a Water Bobble from House of Fraser the other week and that really helped. It was £10, which sounds a lot but cheaper than always buying bottled water....It's a plastic bottle with a carbon filter built into the cap that looks like a rod hanging down into the bottle...the bottle is clear and the tops come in different colours.
You change the filter after 2 months or about 300 litres I think, and the new tops cost £6.99 (from Fraser's, anyway).
Nic x