Aye go for it - just remember to flush out any grot from the pipes.
John
I'd thought the best way to do that would be to just turn the water on before fitting the taps, cistern, etc with isolation valves turned on so that only 1 pipe is "live" at a time and drain 80-100 litres of water from each into a bucket. That reasonable?
Or maybe you can get something that fits on the end of a pipe and connects to a hose, without buggering up the pipe...