After I use 2nd floor bath tub(shower pan), I hear a dripping sound inside the wall. The sound lasts long when the shower is taken long and it lasts short when the shower is short. Luckly (^^) I have not found any water mark on the kichen ceiling which is directly below the upstair bathroom and on the basement ceiling, either.

I hired a handy man to look at it since I thought it was shower pipe leaking (although there was no water mark. How stupid I was... ). He tear off the dry wall and found it was dry inside wall and under the shower pan. It cost me a fortune to put back the dry wall. @.@

Then the handy man went to the basement and concluded it was water dripping inside the drain pipe. I put my ear against the drain pipe and could hear a water drop hitting the bottom of the pipe. Since this drain pipe is perpendicular from the 2nd floor, the handy man explained the sound echoed inside wall and created a loud dripping sound.

OK. This is what I found so far.

I want to get rid of this dripping sound, but there is no slow draining in the tub. The handy man says the hair buildup could be hanging from trap arm causing a little dam to let off the water little by little.

Since this supposed hair buildup doesn't entirely block the drain pipe, I don't know if I should use a hand snake or chemical cleanser. A hardware store clerk told me either of them wouldn't do much good.

So, here are my questions;

1. Is there any other way to get rid of this sound? I tried pouring a bucket of hot water down the drain, but loud popping sounds scared the whole out of me.

2. My house is 35 years old. Wouldn't using a snake or a chemical cleanser damage my old pipes? It seems we have iron pipe from drain to drain pipe and drain pipe is A.B.S.

3. Is it possible to see a water mark long after leaking has started? Although I think I heard the dripping sound inside the drain pipe, it scares me that there might be a real leaking that I didn't find. So whenever I hear this dripping sound, I run down to the basement and check the drain pipe. It's very tiring.

In other words, do we always find a water mark whenever there's leaking?

Sleepless in Toronto, Canada

There is no leak. You are hearing the pipes rub the wood as it expands and contracts.

Thank you for your answer. I actually hired Mr. Rooter guy the other day, and he confirmed the same thing.

I examed it with cold water running only cold water for more than 5 minutes and listened to the sound. Guess what. No sound at all.

I spend about $100 for 2-minute counselling on Mr. Rooter guy, but it was worthy spending 'cause I stopped to put my ear against the wall listening to drip drip drip drip...

Well I would say that there is something in that drain pipe hair or soap accumulation and the water does not drain in a free flow... it take time to empy and it drip.. or when they did the plumbing the drain pipe was not level down to a 1/4 inch a foot... I had the same problem... let me know... :D

Doug nailed it! You're the second complaint in two days about this problem and the cold season's just starting. Knocking, popping, creaking and crackling pipes are a common complaint, especially in colder weather. I can tell you what's happening and take the mystery out of it but you're not going to like the repair. When you drain hot water from your tub or shower it goes into a chase that is a little cooler then room temperature. The heat expands the pipe causing it to rub against the stud to which it is pipe strapped. This is the sound you hear. As it cools it contracts and the noise is heard again. To repair it you must tear open the walls and locate the pipe strap that's causing the problem and shim it tight. Most people when they learn what causes it just elect to live with it. Regards, Tom

Yeh, Tom, I was just going to say: he has the same problem as you e-attended yesterday: Thermal Expansion in Drain Lines. Happens a lot in colder climates...

Question - this is happening to me as well and it is 100+ degrees outside. After I run the shower, I can hear a distinct dripping sound in my wall. I really don't want to have to remove the wall - too much money!

- Austin Texas...