Any Problem with Capping a Tee to a Main Water Line (to once existing sprinkler system)

[Themus]

My son's main water line to his house has a 3/4" PVC tee that branches off to an old sprinkler system not used for eight years. Its near his water meter.

About a foot away from this line we found a shutoff valve that was leaking. He does not care about the sprinkler system.

I suggested he cut the pipe to the sprinkler system back to the 3/4" PVC tee and cap it. It would be no more than 2" or less of a 'stub' coming off the main line.

He is afraid to do that because someone walking their dog told him that mold could develop in the stub.

I cannot wrap my head around that. Seems to me that would be quite common for discontinued water lines being capped rather than cutting a PVC tee out and risking more problems. And 2" with water constantly going down the line seems like no mold would become an issue.

Anyone have any thoughts on this?

 

[John Gayewski]

The dog walker is correct.

It's now illegal (under the uniform plumbing code) to cap tees. They need a way to be purged.

 

[Sponsor]

 

[Jeff H Young]

I didnt review the code but its over kill by a country mile. every air chamber , a tee with pressure guage, fire sprinkler connection , probbebly air hammer arrestors,would be a danger as well .
Id have no problem with capping the tee unless it as john says is illegal in which case I guess I would follow code .
I expect being in the main where all the water usage passes the tee that a less than 2 inch piece with cap wont hurt a thing . I think the code (which I dont know ) would be overbearing to prohibit.

 

[John Gayewski]

Air chambers aren't legal anymore for this very reason (and they don't work). Hammer arrestors have pistons in them that move up and down only when the pressure is high enough which means there's no water in them.

A tee with a cap has no flow. It's just a pocket depositing mold into the water. That's why they finally made it illegal.

I've quoted the code section before in a different thread. 309.6

 

[wwhitney]

I've quoted the code section before in a different thread. 309.6

UPC 309.6 is quite succinct "Dead legs shall have a method of flushing." And Chapter 2 defines "Dead Leg. A section of potable water pipe which contains water that has no flow or does not circulate."

So 2 questions: If you have a capped tee leg that is short enough, does turbulence cause sufficient flow and circulation? That answer could differ depending on which leg has the incoming flow (straight or branch) and which leg is capped (straight or branch). Seems like one or two pipe diameters might be OK, but not sure what authority to get an answer from.

2nd question: if we cap the leg with a male adapter and a threaded cap, does that constitute a "method of flushing"? Or would we need to use a valve? Or maybe both?

Cheers, Wayne

 

[Themus]

I appreciate all the feedback. I would have thought 2" would not be too much that the water circulation would interact enough.

My son in reading this is now wonder if a repair coupling then would be sufficient.

 

[jecottrell]

Interesting reading on the subject.

(I'm not a plumber and I didn't stay at Holiday Inn Express last night....)

South Carolina appears to be IPC and doesn't mention dead legs. (That I could find.)

The dead leg code language is to prevent Legionella from growing.

Engineering and pharmaceutical guidance limits dead legs to 1.5 the diameter of the pipe.

Sounds like if he were to cut the dead leg back and use a Socket Saver to remove the dead leg pipe from the T and use a plug he'd probably be pretty safe. (Hell, it's on the main supply to the house, no? The constant flow is going to be significant.)

My $0.02, and it's probably worth exactly what you paid for it. LOL

 

[John Gayewski]

UPC 309.6 is quite succinct "Dead legs shall have a method of flushing." And Chapter 2 defines "Dead Leg. A section of potable water pipe which contains water that has no flow or does not circulate."

So 2 questions: If you have a capped tee leg that is short enough, does turbulence cause sufficient flow and circulation? That answer could differ depending on which leg has the incoming flow (straight or branch) and which leg is capped (straight or branch). Seems like one or two pipe diameters might be OK, but not sure what authority to get an answer from.

2nd question: if we cap the leg with a male adapter and a threaded cap, does that constitute a "method of flushing"? Or would we need to use a valve? Or maybe both?

Cheers, Wayne

I would venture to say the principal "what goes into a tee must come out of a tee" is pretty relevant. If all the water is coming through one side there is no circulation or flow. Turbulence isn't either of those and would only serve to kick mold out of it randomly.

If there is a male adapter then it's flushable. Not very convenient but it's flushable. We just put valves on them or cut them out.

 

[Themus]

Well my son felt better if we removed the whole Tee and removed the threaded portion out of the water meter and ran a splice into the old line. We did and a couple observations.

--The old line he dug up about 6 feet and it is to my observation schedule 20. Thinner walls than the schedule 40 I have always and mostly used.

--He called me a bit ago, the male fitting we screwed into the water meter is 'moist.' Apparently a small leak. We used t-tape and pipe dope over it. Must not have used enough t-tape.

So we get to try again tomorrow.

 

[Jeff H Young]

Thanks John and Wayne, I didnt review the code and I suspected Themus job was ipc but still find it relevant to many of us.
I really think with out yet reading upc 309.6 that a 2 inch stub buried under ground whether it had a cap buried down 2 foot or a permanant glued cap wouldnt make a differance and if thats the true interpetation that its a total billshit code, maybe the wording leaves a lot to interpetation. if an inspector was that concerned I think he would say hell no to a buried cap presumeably unknown to anyone as a method of flushing . but like I said havent read it yet . Also I could see that some would say a less than 2 inch stub would be self flushing or not .
Themus, I think thats called class 200 I think its junk and never use it for water mains or to the sprinkler valves, You have what you have and can change it all out but at least its good for now but certainly use sch 40 minimum for everything you do in regards to the main