wrote in message
ups.com...
This knocking pipe problem is really strange. It is a weak knocking
sound 2 or 3 times per second normally happened at night time in about
half an hour after all water usage is stopped. Once it started, it
will keep knocking till the next morning. It really drives me crazy.
The only way I found that can stop it temporarily is using water like
flushing the toilet. It will stop the knocking about another half an
hour. So imaging that, wake up by the noise at 1:00AM, flush the
toilet, try to get back to sleep before 1:30AM, if not, flush again...
Anyone can give some advice?


Instead of wasting the water on a flush, take diuretics and make the flush
do something.

Do you have shut off valves for each fixture? Try shutting off some of
them, or a zone if a section must be shut down and see if that stops it or
help locate the problem. My guess is that a toilet valve is not closing
properly and while barely visible, is very loud. That would be the first
place to check.