I know there are multiple benefits to having a water butt besides reduction in a metered water bill, but in somewhere like the UK where water prices are low enough anyway, is the cost of a water butt outweighed by the reduction in water bills? Some water butts can be quite expensive, especially with installation so I wonder weather it's worth it based on that.
When I was young, one of my aunts had a rain barrel that she used for water to shampoo with. She used well water for household purposes and used the rain water only for shampooing. She lived way out in the country in a very old house with a well seasoned "tin" roof. These days in most areas rain collected off roofs can offer many sources of pollution, so you must be careful to be sure that water collected from your roof-top is not contaminated, unless you are using it for gardening, laundry, or flushing toilets.
