I've been reading through some of the other posts about knocking pipes trying to find an answer to what's going on in my home. I've got a few ideas going in my head, but I know NOTHING about this sort of thing and I don't want to mess this up. Depending on the fix, I wanted to try to do this on my own...without bugging my husband! So, onto the problem. Several months back we replaced out kitchen sink and about a month after that we added a Brita filter. I'm trying to remember if the problem started before or after the filter..I believe it was before. Our pipes now knock. Always when the kitchen sink is in use, but sometimes I will hear knocking when nothing is on. I'll hear a random knocking and then I'll hear water come out of the shower head in the only bathroom in the house. Not sure how old the plumbing is. The house was built in the early 1950's and we've only owned it since Feb 2005. Is there any easy fix to this? Someone had told me to get a knock valve. Will that work? Is that easily installed? Thanks!