Hosepipe bans and motorhomes

To clarify, our water and sewage is 10 x £56, £560 payable to Severn Trent.
 I've just completed this usage calculator and even being conservative by not including the spa etc, the estimate comes out at £405 pa. So what I have to ask myself is a saving of up to £155 worth the hassle of stressing every time I suspect water is being used excessively..
That works out at three quid a week, which I can easily save by cutting down my weekend wine consumption by a glass or two...
Al.
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