Any debts to water companies are treated differently from money owed for gas, electricity and telephone bills. It is illegal for a water company to disconnect you for missing payments. The only way they can force you to pay is to get a 'money-only' county court claim (see 'The 'money-only' claims procedure' for how this works).
If you have missed payments on your water bill, find ways of paying other household bills first. But you should try and make sure that you have enough money to pay your water bills in the future.