I am at my wits end in attempting to replace some cracked CPVC pipe. There is a middle section that has cracked and here are the steps I tried to replace:

1) Cut both ends of the leaking section
2) Wipe dry cut end right
3) Apply glue to coupler and give quarter twist (to the cut piece on left)
4) Wipe dry cut end on right
5) apply glue to coupler and give quarter twist
6) Since other end of cpcv pipe is already connected apply glue and twist best I can ****Not sure if full quarter turn due to pipe already being connected on this end, and this is where drip always occurs from!

What can I do differently to the end that is already connected to get a good quarter twist so we get a good seal and do not have a slow steady drip?

The left side of the image in the red square is what leaks (the elbow) as I attached starting from the right to left and the left elbow is the last "twist" that I need to make. Image

  • what does this mean? cut end right ........ it is unclear what you are describing. ... please post a picture. – jsotola Jan 21 '18 at 21:33
  • @jsotola - what is that piece called? Would my local big box store carry that? – BoJack Horseman Jan 21 '18 at 21:40
  • One thing you may be missing is to use PVC primer before applying the normal cement. Old PVC can get harder than new pipe and primer can really be helpful as it softens the pipe surface. Primer is often purple or blue in color. Another thing to keep in mind is the necessity to cement both the inside of the fitting and the outside of the pipe for each joint. – Michael Karas Jan 22 '18 at 2:53
  • I'd be looking at replacing the entire 'u' section. The fittings are cheap. Give yourself a nice clean cut on the vertical tube to work with. – agentp Jan 22 '18 at 16:53

Your surfaces need to be clean, smooth and dry, and the pipe needs to be the correct dimensions.

A glued (welded) pipe joint needs to be a snug push-fit connection without the glue, with no play in there. At least in the UK, there are different pipe diameters which are close but not close enough, and these simply won't work because the pipe solvent won't fill the gap. You can get adaptors to join different pipe sizes. Usually you need to twist the pipe in, which is a good thing because twisting ensures you don't get "channels" inside the welded joint.

Then we come to "clean, smooth and dry". Paint and grease are the usual problems here, as well as water if the pipe hasn't dried out for long enough. In your case though, you have a different problem. I can see from the picture that someone has slapped a load of silicone sealant round the pipe, presumably in an attempt to stop the leak. Silicone sealant itself will stop anything sticking to the surface, when removed it leaves stray little flecks of itself behind, and it leaves a greasy surface finish which also stops things sticking to it. I think you need to replace that entire section of pipe, because you'll never get a good joint on a surface contaminated with silicone.

And then of course you need to leave the water off for long enough for the solvent to weld the joint. Check your solvent for details here. Typically they'll say a minimum of somewhere around 4 hours, but I'd personally give it 24 hours (or at least overnight) to be safe.


use a cpvc union like this one

enter image description here

  • Wouldn't I still need to glue and quarter twist the current pipe into the union? So at the end I would be left with a piece I am unable to quarter twist? – BoJack Horseman Jan 21 '18 at 21:49
  • As long as there is room on either side of the coupler location it is simple to separate the two parts and glue/twist each end separately. – Michael Karas Jan 22 '18 at 2:47

One of the problems with gluing pipe that has been in service is drying it out first. CPVC or PVC should be thoroughly dried before gluing.

Try using a hair dryer to make sure it is bone dry before you begin.

The twisting isn't as important as giving it some time to cure. You can't turn the water on right afterward. Give it a few hours.

(This is one of the reasons PEX is becoming more popular. Making repairs to wet pipe is much easier.)

  • Hmmm....I have been getting a towel and very very drying the pipes (but I am not a plumber and this is my first time trying to replace any plumbing work) before trying to connect. As far as giving the glue time to cure, I have waited 30 minutes from glue time to turning the water back on. I should wait a few hours? I like the hair dryer tip, that is a great idea! – BoJack Horseman Jan 21 '18 at 21:57
  • Yeah you could use the hair dryer on the pipe after gluing to shorten the cure time. Sometimes water sits inside the pipe and if it isn't dried out it wrecks the gluing operation. – ArchonOSX Jan 21 '18 at 22:00
  • Do you recommend gluing the coupler/elbow or gluing the cpvc pipe that I insert into the coupler/elbow? I was not sure which one was "better" if at all – BoJack Horseman Jan 21 '18 at 22:04
  • 30 minutes drying time is not long enough. i would give it overnight. – jsotola Jan 22 '18 at 3:31

You need to wet all the connecting surfaces with the yellow glue. The surfaces need to be clean, straight cut and dry and never glued before. Dry time for CPVC at room temperature is minimum of 4-hours. The quarter turn is optional.

  • Yellow, glue? My local box store sold me some glue that is white. Maybe that is part of the problem. And it was roughly $15 for the "jar" and smells dreadful. Def have straight cuts, got one of the cutters that are similar to a giant pair of scissors. – BoJack Horseman Jan 21 '18 at 23:13
  • 1
    it is not glue. it is a solvent that partially dissolves the pipe and the fitting. the two parts then "flow" together to create a seal. – jsotola Jan 22 '18 at 3:33

Simplify your life and get some push fit connectors. The pipe can be soaking wet and they still work. If you mess up, you can take them off and try again. They are more expensive, but this seems like the perfect use case for them.

  • Can you provide an image? --- like the sharkbite is what I see in my search results – BoJack Horseman Jan 22 '18 at 18:41
  • @BoJackHorseman Shark Bite is one brand of them. – poorplanning Jan 28 '18 at 23:50

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