Best Way to Repair Leak in 4" PVC Sewer Drain

We live in a 9 year old three story town home. We recently noticed that the main 4" sewer drain that carries the waste water from the top floor toilets, showers, and washing machine has sprung a leak just above a 90 degree elbow joint down on the main floor, just prior to the point where this pipe enters into the main sewer exit line for the entire house. When we flush a toilet, we get a couple of tablespoons of water from the leak. When the washing machine drains, we get about a cup full. We did not notice the problem until just recently,but it could have existed for some time because it was hidden by ceiling drywall. We've now cut away enough drywall to see where the leak is occurring and access the leaking joint.

Is there a code-approved method of patching a leaking joint in a drain line? There is little internal pressure in the line. I have seen some rubber clamp-on collars at the big box stores. Would one of those be acceptable for a repair?

If the drain lines were ABS, I'd just cut it out and replace the entire coupling.

If the leak is coming "from" the joint, cut out the fitting and replace it. Nothing I am aware of will seal the leak permanently. The collars you referred to are probably No-Hub or Fernco couplings, and are made to connect pipes. You can use these to hold the new fitting in place instead of gluing two couplings in.

Yeah, you gotta cut it out and glue in a new fitting.

As a side note I noticed you said "Fernco" Majak. I thought for sure that was only a Detroit term. Fernco's originated here in Ferndale, Michigan. Which is a neighboring city of Detroit. I thought most of the country called them rubber couplings or something. I'm just surprised the term "Fernco" is used elsewhere.

CHECK WITH YOUR HOME INSURANCE THIS COULD BE WHATS CALLED A
LATENT DEFECT AND IN SOME AREAS COVERED BY A 10 YEAR WARRANTY

OTHERWISE TELL YOUR INSURANCE CO. IT WAS A SUDDEN FLOOD AND THEY
SHOULD COVER ANY DRYWALL REPAIRS OR OTHER PROPERTY DAMAGE
JUST NOT THE REPAIR TO THE PIPE ITSELF !

THE ONLY PROPER WAY IS TO CUT OUT THE JOINT AND REPLACE IT
ANY OTHER WAY IS JUST A MAKE DO BAND-AID THAT WILL CAUSE FUTURE
PROBLEMS DOWN THE ROAD,
I DON'T THINK YOU WANT TO PLAY WITH YOUR FAMILY'S HEALTH AND
SAFETY !

Reedwalker, I always considered it a brand name. Kinda like Channel-locks,even though most people call water pump pliers, channel-locks. Biggest difference between Fernco and No-hub is that No-hub can be buried.

JERRYMAC said:

CHECK WITH YOUR HOME INSURANCE THIS COULD BE WHATS CALLED A
LATENT DEFECT AND IN SOME AREAS COVERED BY A 10 YEAR WARRANTY

Click to expand...

I'm familiar with latent defects, and this is exactly what it is. We have a 10 year warranty. It excludes pipe leaks after one year, but this leak was hidden until we saw staining on the ceiling. So we'll try to get them to cover it. Thank you all for the replies.

We use `FERNCO` fittings here in the U.K. - they have been available for Years.

"Regards" to all my U.S. colleagues.

What else would you call a Fernco? A "rubber coupling"?!!?