As it stopped when water turned off, that would point to a faulty inlet valve, but as that has been changed, should be ok, But, new one could be faulty. the other way for water to get in is via the outlet, check your drain pipes are clear to where ever they go outside, not sat in water, as that would cause it to back up, need to have an air gap at open end. if m/c outlet is fitted to a drain outlet under the sink, again if pipes not clear, when you drain sink it could flush into m/c If you have the m/c outlet in to a stand pipe, hooked into top, make sure not pushed too far down, just needs to be a few inches, to hold it in place.
SD, December 2011
