Good reply from Trevor but I need to add that if you go down the route of tapping into the water supply then you are breaking the law if you don't have a permit to use water ( from a standpipe).We have just had a standpipe license for some works in Islington, a month of use cost £120.00, they can and do come out and check your kit and if you damage the standpipe you are liable.If you do use standpipes and do not have a license the fine if and when caught is £20000. Cost the water usage into the job.Rob