A major player in the UK water supply industry has called on the nation to refrain from pouring the grease and fat from their festive feasts down their sinks this Christmas.Thames Water has issued an appeal on its website urging households to cut out the fat and lessen the impact that the waste from millions of roast dinners could have on the nations plumbing.Thames Water flusher Rob Smith, who is employed to clear blockages in the sewers underneath London, said This is our busiest time of year, when an estimated 25 per cent more fat, oil and grease is poured down the drains as people enjoy their Christmas dinners.Everyone forgets that the sewers are only meant to take away water, toilet tissue and human waste. Anything else - including fat and grease and even items that are marketed as flushable - can put your pipes at risk of nasty blockages, as they wont dissolve.The company expects as much as 500 tonnes of fat to be poured down the drains by its customers alone over the Christmas period equivalent to 1.8 million blocks of lard.Some food waste will inevitably find its way into the water system, but the impact of that amount can be kept to a minimum by using an In-Sink-Erator food waste disposer.