PEX for pumped drain line

[Neil Wick]

Hi all,

This seems very difficult to find: does anyone know if it is OK to 1-1/2" PEX in a pressure wastewater drain line?

Thanks in advance!

 

[hj]

THe only downside i can see would be the restriction from the inserted fittings, but since it is forced drain, I cannot imagine that it would be a problem.

 

[Sponsor]

 

[Neil Wick]

THe only downside i can see would be the restriction from the inserted fittings, but since it is forced drain, I cannot imagine that it would be a problem.

Theoretically, I can upsize to 2" if I had to. I have a screw up that I need to fix. I have an exit line from a grinder pump station that is 100 ft long. The last 60 feet were piped with foam core pipe on accident (but pressure fittings). The pipe is buried already, but I have access to both ends. I am thinking of attaching the PEX to one end and pulling it through the dirt.

 

[Reach4]

Are you sure that DWV pipe is not OK for that application? How much pressure can your pump build into a clog?

 

[Neil Wick]

Are you sure that DWV pipe is not OK for that application? How much pressure can your pump build?

The pump is 2.5 hp, so it can be up to 80 psi if there was a clog. DWV is only rated to like 5 psi of hydrostatic pressure. I think it is on the harry edge because it's open-ended to the sewer pipe and it should be laminar flow by the time it hits the DWV pipe.

 

[Mliu]

Have you considered the economics of switching to PEX? Sixty feet of 2" PVC is ~$45. One hundred feet of 2" PEX is over $600. You can buy a heck of a lot of manual labor for $550.

 

[Neil Wick]

Unfortunately, there is already landscaping done, so it would be very expensive to dig up. I just spoke with the grinder lift station company and they said it would not be an issue with them to do 1-1/2 PEX even with the reduced area at the connectors.

 

[LLigetfa]

Are you planning to leave the 2" PVC in place and fish the PEX through it or are you pulling out the PVC and pulling in the PEX at the same time?
Not sure why you cannot pull new PVC through while pulling out the old PVC. Is it a straight run?

 

[Neil Wick]

Are you planning to leave the 2" PVC in place and fish the PEX through it or are you pulling out the PVC and pulling in the PEX at the same time?
Not sure why you cannot pull new PVC through while pulling out the old PVC. Is it a straight run?

Yes it is a straight run. The current PVC is 1-1/2", so no I was not going to pull the PEX through. I had not considered pulling. I was not sure it would work. That is actually a very good idea, as I would only need to pull the 60' until I got to the pressure pipe.

 

[Mliu]

If you're going to pull PVC pipe, I would recommend getting 20 ft sticks with bell ends. Be sure to chamfer the end of the pipe to be inserted into the bell. Use best practices for cementing the pipes. Allow the PVC cement to cure at least 24 hours before pulling the pipe. Pull it in the direction opposite the bell ends.