[fluffymunchkins]

you can buy these water bottles and holders, which work well by justhanging over the side of the tank.
Accessories : Superpet Universal Water Bottle 236ml : www.EquineCanineFeline.com the place to buy all your Pet Products, Horse Products and Pet Supplies online
they are 99p if you spend over a certain amount
and the holder for hanging it: Accessories : Superpet Universal Water Bottle Metal Holder - So Useful! : www.EquineCanineFeline.com the place to buy all your Pet Products, Horse Products and Pet Supplies online