pressure testing the DWV system

[MikeT]

I have my DWV system laid out and (mostly) glued together.  After I put the final pieces on, I will need to pressure test it.  I assume I need to cap off the ends of on every pipe except for the pipe that will be 10 feet high and filled with water.  Is that correct?  Also, does it matter whether I fill a 3" pipe, a 2" or an 1 1/2"?  

Finally, am I correct that the inspector will come out and look to make sure the water is holding and that the layout is appropriate/follows code?

thanks,
mt

[glenn kangiser]

Correct on that.  Size makes no difference -- in this case.  1 1/2 to 4" is OK as long as it has enough head.  That is what makes the proper amount of pressure.

You can stuff the toilet holes with tightly wrapped news paper with bailing wire around it for a removal tool then pour in a non-shrink grout such as Pour Stone about 3/4 inch or so deep if you don't have caps, then break out the grout and remove the paper after the test.  Saw an old plumber do this once.

[MountainDon]

I saw a test done once where they used the vent stack as the water column. It was done by a plumber and he had those inflatable plugs.

[MikeT]

For my test, I think I will attach a 10' pipe on what will eventually be my cleanout.  I will do this because it is easiest to look at for an inspector.  He will not have to go down into the basement--simply peer down in the rough stair opening, and you will be a be able to see the pipe (hopefully) holding water.

Thanks,
mt

PS: for the other openings, I do have those cheap caps that fit (read: glued) inside the pipe.

[ScottA]

You'll need to let those glued plugs dry overnight or they might pop out when you test. They still might pop out if they don't get glued good. Don't spare the glue on them.

Scott

[MikeT]

Thanks, Scott.  I will just wait on the water, then.  The inspector will come over for another type of inspection tomorrow, and I will ask him to look at the DWV set up (and hopefully give me a thumbs up), so then he will just come over the next time to see the 10 foot head.

mt

How often does the glue not seal well?  Is it pretty rare?  The instructions on the can indicate you want to avoid puddling which led me to make sure the glue was applied evenly and so on....

[glenn kangiser]

Generally the glue sticks pretty good if you can see that you have put it decent on both pieces.  As Scott said - overnight is good.  Sooner can work but not always reliably.

[ScottA]

Those test plugs are so thin that the bonding surface is really small. You shouldn't have a problem with the fittings though. I stopped using the glue in plugs because I couldn't afford to lose a test and a day on any job. Miss one little spot with the glue and they'll blow out under head pressure. Just use care in gluing and let them dry good and you should be ok.

Scott

[glenn kangiser]

Good point, Scott.  They are really marginal.

[MikeT]

Okay, so here's where I am with the DWV setup:  I glued it up yesterday morning and let it sit until late this afternoon.  My father was the kind soul who drove the 2 hours to the job site and filled the pipe.  After getting it topped off, he went and puttered around for about 20 minutes and returned and noticed that the meniscus that was on the pipe had disappeared and the level had dropped to about 1/32 of an inch below the top.  

I am not going to call in for an inspection and will instead head over there tomorrow or Tuesday morning and check out the levels myself.

If I indeed have a leak, it could be from a glued joint or a cap.  I am planning on putting newspapers underneath each joint so I can tell if it is there.  

If there is nothing showing on the newspapers, I suppose I  look at the knockout caps carefully to see if they are showing any signs of leaking water.

Does anyone have any words of advice?  Tricks of the trade?  

Thanks,
mt

[MountainDon]

Use a dry tissue to wipe around all potential leak spots; that'll show water quickly.

If I'd thought this through before I would have suggested adding some food color to the water. That would show up well on tissue or cloth wipes.

[MikeT]

Thanks, Don.  I was also thinking that on parts of my setup, where I have some vent pipes stubbed up and capped off, that the leaks could initially be air until it is replaced my water.  What if I took Saran Wrap and rubber bands and wrapped the capped ends.  In theory, if the water is pushing the air and I have a small leak, shouldn't it start to push on the saran wrap and kind of blow it up?

I am thinking that any leak I have is a tiny one, so it might be a slow diagnostic process.

mt

[MountainDon]

In theory. How that translates into real world is hard to say. And yes I think you're right... if there's a leak it's a small one. It will be interesting to see if the level continues to drop or not.

[MikeT]

I do not know if any drop is acceptable or not.  In reality, the system will never be under pressure like that, so I do not know if one small leak (in a cap for discussion's sake) is a deal breaker or not.  If the level drops 1" over 24hrs, if that is a big deal or not?

[glenn kangiser]

I  would top it a few minutes before the inspector arrived.  Add those extra drops.

All I could find was that it needed to be maintained for at least 15 minutes prior to inspection.

If I found a tiny leak I may just plug it with some hydraulic cement.

Its not often you have a leak if you glued it good.  I have actually seen a bad piece of pipe before though.

[MikeT]

I thought about that too, but I live two hours from the job site and have a full time job.  So far, I have never been there when the inspector is there.  I wish I could be.  

Hydraulic cement.  Tell me more.....

mt

[glenn kangiser]

Quickcrete or others make cement that sets rapidly under water.  Usually in small pails.  If you have a little seep, just mix up a little gob - smash it in the leak - hold it a few minutes and it should stop.  We did that for concrete pipe repairs at the Widow Creek Trout Farm when I worked there in the late 60's.

I have patched little seeps with abs glue also but not too easy.  Nothing beats a well glued joint though.  How much you want to try just depends on how hard t is to do it the proper way and what the whole situation is.  I guess you would say -- it depends.

Looks like it's just recommended for concrete but I have used it for cementing plastic to concrete in irrigation applications.

http://www.quikrete.com/ProductLines/HydraulicWaterStopCementPro.asp

[MountainDon]

Hydraulic cement is great stuff!  

We have concrete block walls around our suburban property. The year we moved in I had problems during/after heavy rains with water from the next door yard seeping through a few places in the mortared joints. Pushing some into the cracks while the water was coming through, and holding it in place like Glenn said stopped eveything up. It's 22 years later and there's still no water coming through even tho I've seen some ponding on the other side after a good rain.

[MikeT]

Thanks, guys.  For me, I think much depends upon where this small leak might be coming from.  If it is on a cap, then I might just go for it.  If the leak is on a joint, it might depend where on the pipe it is.  I think I would tend to worry more if it was/is on the bottom than on the top.

mt

[ScottA]

It's normal for it to drop a little when you first fill it. Air gets trapped in the high spots and will take a bit to equalize. Just let it sit a bit then top it off again. Be looking for leaks while it's resting. If you find a leak then you may have to repair it before you can pass inspection.

Scott

[MikeT]

Well, it passed.  I was worried because the 2" pipe had lost about two feet over two days.  I topped it off and the inspector came and didn't seem concerned.

But he did ask me to put in some insulation between the pipe and the wall in case it freezes.  This is the Oregon coast--it never freezes.  Anyway....I passed.

Pouring tomorrow.

Thanks for your help.

[glenn kangiser]

Good Job, Mike.

[desdawg]

Good deal Mike. Green tags are my favorite!