1

I have an existing drain pipe that takes water from our roof catchment, and sends it down into our drinking water tank (this is our household water supply). We now have a new building, and I wish to route the extra rain water from this roof into the same pipe. So I want to add a T-junction to this existing pipe, and route the new roof pipe into it.

I have repaired broken in-ground agricultural pipe sections before, but had (too much) trouble trying to insert joiners as there is no "give" in the buried pipe. Eventually I used rubber-sleeve type joins, but am unsure of using these with drinking water.

So, short of digging up 20 metres of pipe to get some extra bend/movement, with an existing 100mm UPVC "poly" pipe in the ground, is there technique for adding a new T-intersection?

Not relevant: Add T fitting to pipe

3
  • Is this polyethylene pipe, at 100mm (4") - that's what "poly" means in my area, usually, but it's not common for 4" pipe (more typically polyvinylchloride, called PVC.) – Ecnerwal May 13 '20 at 2:00
  • Ah, "poly" = UPVC pipe. I will edit the question. Ta. – Kingsley May 13 '20 at 2:03
  • are you sure that the existing pipe has sufficient capacity? – Jasen May 13 '20 at 12:27
3

One technique with a little more digging, but not a lot, is to cut out a section of pipe, add 4 elbows to make an offset and put the tee in the offset.

Depending on what fittings you can get, there are also "saddle" or "snap" tees made to attach by clipping onto the pipe (and drilling a hole, and gluing, typically.)

This assumes that the pipe size is sufficient for the flow from both roofs - otherwise, you might be better off with a new pipe from the new roof right to the tank.

0
1

I'd usually approach this with a pair of slip couplings.

  1. Build an insert composed of your new sanitary tee and short pipe stubs on each horizontal end.
  2. Slide slip couplings on each stub (without cement).
  3. Cut the existing pipe twice at the width of the assembly from step 1.
  4. Drop the assembly in place and slide the slip couplings over the joints, cementing them in.

If you plan well you can do this by reusing the section of pipe you cut out, saving the cost of new pipe.

1

Oatey and other makers of PVC piping have PVC saddle tee kits that cost about $20.00, that allow you to make a tee in an existing pipe layout. Look it up, it may solve your problem. You also mentioned that the rubber couplings may not be compatible or suited for drinking water. If the collected rain water is not filtered and treated correctly I would be more concerned about it not being safe to be used with drinking water than to worry about a rubber coupling.

2
  • "If the collected rain water is not filtered and treated correctly I would be more concerned about it not being safe to be used with drinking water than to worry about a rubber coupling." Very much this! If you're treating your rain water to make it safe for consumption, it should handle whatever trace bits of contamination the water may pick up from the rubber coupling. – FreeMan May 13 '20 at 15:00
  • I don't understand the reasoning behind the rubber coupling comment. Just because I cannot control all the environmental factors in my water supply, that means I should ignore possibly negative factors I can change? – Kingsley May 13 '20 at 21:39

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.