Originally Posted by zzoo
I may sound bit stupid here, but is there any way to fix that dripping noise without breaking the walls ?
No, unless you can use a mechanic's stethoscope to pinpoint the source of the sound, and it happens to be in an accessible location, you can't fix this without taking it apart. Basically, this is just one of those things about a large complex assembly like a house that's put together by the hands of sinners that's not perfect. Even a brand new house or building will have little things wrong with it like this. This is a very common problem. It's not so much a problem as it is a concern. Once people find out that it's water pipes rubbing against the wood framing of the walls, they're not concerned any more.
Only get concerned if you SEE evidence of water leakage.