when toilet flushed, sink used, shower etc...cold water, there is a tap, tap, tap, tap, tap, tap etc. about 4 per second in the pipes....when toilet is done filling, it stops. As toilet slows near the end of the fill, the tapping slows. I've replaced pressure regulator incoming...no difference. Did the 'cure for water hammer thing', no change. My guess was bearing on the water meter at the road transmitting sound thru the pipes...water company says nope. ANy ideas?