View Full Version : Waste Pipe Leaking

06-18-2011, 04:19 PM

I have a leak in the waste pipe coming from my kitchen sink and dishwasher (I think?). The pipe leads into my main waste line, and has one large (cast iron?) pipe leading into it as well as a skinny copper pipe (could this skinny pipe really be a waste line?). The leak is after those two pipes come together, and before it reaches the main line. I have attached pictures of the leaky spot and area below. There are actually two spots where it is leaking, one under the white tape and one a little bit to the right. It has a slow drip all of the time (even when the sink and dishwasher are not running), but leaks faster when the sink is running. Any suggestions?



06-18-2011, 05:25 PM
Where does the copper pipe come from?

The cast iron section needs to be replaced. Depending on where you live, you may not have a choice but to replace it with CI. Otherwise, it's generally easier and less expensive to replace with PVC (or ABS, if that's what's used in your area). As to the copper, yes, it could be a drain, but based on the size, I'd question what it may be supporting. Whatever it is, going into that larger section and then necking down to a smaller section means that instead of any waste just flowing through, that section will always have water and waste in it (at least based on what I think are the installed angle). It's generally never allowed to go from a bigger pipe and funnel it into a smaller one in waste plumbing - you can only stay the same or get bigger.

06-18-2011, 05:48 PM
It is a galvanized steel pipe which was installed by someone who did not know about plumbing. They used the wrong fittings and also the wrong TYPE of fittings when they installed it. The copper line may be someone's "bright idea" for a diswasher drain, and if so it reinforces the fact that they were NOT "plumbers". That section should be replaced, and since the fittings used could have contributed to the corrosion you might want to have other exposed drains checked since I am sure they did not get "smarter" by the time other pipes were installed.

06-18-2011, 06:40 PM
Thanks for the replies. I am pretty sure the copper pipe is coming from the dishwasher, which is located right above this basement section (it is never used as we always hand wash). The "larger section" you guys are referring to is a "T" that is combining the copper pipe and other, larger pipe (hard to see, towards the top right of the screen) which is the drain pipe from the kitchen sink. So does what you said still hold true, that there should not be any larger sections (the T) going into smaller sections? PVC is used here, because I can see the second bathroom waste lines are PVC. Is it a big project to replace this section with PVC? Appreciate the help.

06-19-2011, 07:06 AM
Hi Glen...

Best solution is to cut out the old galvanized piping back near the 45 degree fitting and then unscrew the the remaining galvi. pipe from the 45 degree fitting so you can use a PVC threaded male adapter to transition over to PVC and repipe this correctly, or you could also use a shielded transition clamp to attach onto the galvi. pipe in front of the 45 degree fitting. Next, you would need to go upstairs into the kitchen wall and open the wall up under the sink and remove all the galvi./copper piping going to the sink, but leave the galvi. vent piping in the wall so you can attach to it using a shielded transition clamp and then repipe all this up in PVC.

Important points include:

Use a sanitary tee fitting to stub out of the wall for the kitchen sink.

Need a full size cleanout at the end of the piping run in the basement just after your new WYE fitting and street 45 fitting (combo. wye) go vertical to pick up the kitchen sink. Here, I am betting that there was a cleanout plug in the end of the tee and then somone came along and added the dishwasher drain piping to it.

Install a branch tailpiece at the sink strainer and hook the dishwasher drain hose to that or if you have a disposal in place, hook the dishwasher hose to the dishwasher connector at the disposal (be sure to remove the "knockout" in the connection).

Install a hanger in the basement near the new wye fitting.

Finally, if this all seems too much then it probably is and you should consider calling in a local licensed plumber as they can usually make pretty quick work of this.

Good luck!

PS: If you do cut into the wall under the sink be careful of the weight of the vent...may need to support. I would also tell you to support the drain line in the basement while cutting all this out...just to be safe, OK?

06-20-2011, 12:02 AM
Hello everyone
Pikabb see in most of the cases these leakages is due to the gap created in joining the two pipes or where pipe takes the turn and once case can also be of collection of garbage in the pipe. So wrote that you attached some pictures but I could not find any of them. So please attach some pictures so that I can give you the clear solution.

06-20-2011, 06:16 AM
quote; Here, I am betting that there was a cleanout plug in the end of the tee and then somone came along and added the dishwasher drain piping to it.

Handymen are ALWAYS using cleanouts for something else. I guess they think that plumbers are so considerate thay we just put in openings for them to use later.

06-22-2011, 01:39 PM
Thanks for the replies.

I had a plumber come in yesterday (I am not comfortable replacing pipes). Turns out I may have a major problem on my hands. In addition to this leaking pipe, I had water leaking into my kitchen, which I thought was from a faulty seal on the upstairs toilet (had a separate thread for this). They checked the stack that leads upstairs to the toilet, and said it is no good. When we run water from upstairs, we get leakage around the pipe in the basement. They also said that this bad pipe could be what has caused the problem with the horizontal pipe I was referencing in this thread. I'm not exactly sure if that makes sense. They gave me a quote of $7400 to replace the main stack pipe which goes to the upstairs bathroom and the leaky pipe in the basement. Are they taking me for a ride? They would have to remove kitchen cabinets and parts of the kitchen ceiling to get to the pipe. I am going to try and have at least one other person come in and give me an estimate, but I am struggling to get recommendations for good plumbers. Any advice?

Thanks again,

06-22-2011, 04:50 PM
Ya, without better information, I would be uncomfortable.
As a general rule you should have at least three quotes before spending that much money and get a consensus on what is wrong.
If you need a repipe then the cost may be reasonable, hard to tell, get a second opinion.