How to Diagnose Plumbing Drain Problems | Ask This Old House

[Music] how long you guys been here about 30 years and lately in the last few months we've noticed a smell sewer smell coming from this this bathroom okay is it all the time no it's not okay not too bad right now no we've noticed that the smell occurs whenever we use one of the fixtures upstairs okay and then we also notice it in the toilet the water we have movement of the water here when we flush upstairs or use the child do you do me a favor you run up and just go flush the upstairs to the order oh yeah well did you see it absolutely that water level bounce when you flush the toilet and it really shouldn't anytime I see that it suggests something to do with the venting system the air that's inside that pipe is not getting out through the roof well that's what we thought and we call the plumber who came over and put a camera down our vent okay so that's right down here yes to the right okay so we are right behind the bathroom and here is your drain waste and vent system for the whole house got a clean-out right here the drain line probably goes underneath the bathroom and out the back of the building now you can see right here here's where the water comes from the lavatory right behind us the toilet comes into here but at this point this pipe right here this full-size pipe goes out through the top of the roof it acts as a vent to let the sewer gases come and go a lot of times we find that animals get up into the top of it they you know the methane makes them die they fall down into and then they clog the vent now did they run the drain camera down yes they did and didn't find anything of course all right so what else do they check so the next step was to remove this cap and put the camera down this drink and what they find I found that 22 feet away there was a water accumulation there shouldn't be any water in a drain line think about it that drain line goes out like this with pitch shouldn't be any water except at the moments when you're running water or flushing something so they found water you found water so where's 22 feet take us up here into the far corner look at you you've been busy been digging I have been digging there's an access door here and I remove that broke through the concrete yeah and started to dig and this is what I found now that's not what I would expect I would have thought that the line would leave and go out to the street or this way or that way but it doesn't actually turns upwards it doesn't really go too far doesn't it must go up maybe an old downspout line let me do this let me go out and grab my camera and see if we can figure out this all right rich here is a sort of a drain snake except it doesn't have a clean-out at the end it actually has a camera and a light you can see me see what the previous guy saw so we're going to go down through the drain now down in the horizontal look at you see that there's water in the pipe should be water there under water and we're going ten feet if stats get less water that's weird okay let's keep going up all right so as we get out of little ways here now look at this net of the pipe the pipe takes a turn you see it no love it was straight now if I was seeing a stoppage I'd expect to see tree roots or some sort of thing but this doesn't this actually dives downward and this standing water right there I think I know what this what this might be so rich I made a mock-up out of PVC of what I think might exist underneath us somewhere right here it would be cast iron but this is the PVC version of it you know our cameras at a place right about here I think and right below is a thing called a house trap now house trap is filled with water from here to this point they're also called rat traps because back when you had a cesspool they were worried about rats or rodents coming straight up the pipe into the building with the water seal right here it meant that the rodent wouldn't go readily through the water now these are falling out of favor for a lot of reasons one is you can't just run a drain snake to clear a stoppage you know without the trap you come right through it would clean the line you would go out and get the tree roots and stuff like that yeah with a rat trap like there's a house trap it means I could have a stoppage here I could have a partial stoppage here but I could never get at it okay I say now to get around it they always had cleanups and that would let you come in this way or come in this way but it required that this whole house trap was readily accessible I would have assumed it was right here in the access right now we know that with 20 or 22 feet from point-a over there but we don't know whether it's here over here it could be outside the building so what I've brought is the next generation of this drain camera locator the camera sends out a transmission signal and this is a locator to tell exactly what ahead of the cameras so it's pretty cool beam so let me just power it up and we're going to find this a day so this thing is sending out the head of the cameras sending out a magnetic signal much like the earth have a north and a South Pole and the head of the camera represents the equator so I'm going to find the two poles let's grab those two red markers okay put one down right underneath me right there okay so now it tells me the pipe goes this way and the other the other pole is right there market right there and guess where the equator is rich right in the center we hope okay thank you just drop your yellow light there okay so that tells us that that is the exact location of the head of the camera it also tells us that it's two feet eight inches down all right so that is not pretty though because we still means we're gonna have to dig all this up if we're going to go after this house travel before I have you do that there's one more thing that's bugging me and that is all that water that was in that pipe early on thinking going to do one more test to determine if this is the cause of the problem over there let me show you all right so let's just review here's our house track and we have a camera that's sitting right about here we can see the water level right here in this whole Travis fill with water we really want to prove whether or not we have a partial or full obstruction in the trap or in the line that goes out to the street so in normal operation when we flush a toilet this water level should stay where it is but if there's a little restriction the level will probably back up it obscure the lens and it'll take a while for it to drain back down so why don't you flush the toilet and give this test okay [Music] hmm very interesting and you know that we just proved that this trap actually it does not have a restriction it that water went through it but I saw something else I saw the level go down which makes me want to check what I am I think you know the water that we saw early on just a sec yeah at 15 feet out there's water there's just a little bit of what see how it's in the bottom third yeah but now as we come back see this at ten feet out the pipe is almost filled with water still at 9/8 so now we're back to what three feet and I start to see the lens again alright so from 15 to 3 feet it's fill with water that's 12 feet of water in the pipe I think I know what the issue is I think the pipe has sagged imagine this house was built 60 years ago plumbers would have come along and done these cast-iron joints that have poured lead and they would have laid them on to sand underneath that bathroom and I think over time maybe the sand let go and none of the fittings let go and a pipe sags like this okay that pipe now is going to have a place where it sits with water in now you create another trap you end up with a trap out of the house trap another one back here now you flush a toilet the air that's in the pipe needs a place to go it starts pushing backwards now it makes the toilet bounce like you have and it might also make those cracks and the fittings under the ground might let sewer gas come out underneath it might seep up to the concrete now that's where the smells I think so so what's the solution well we know from 3 feet to 15 feet that pipe is sagged it means the only way to do it is to go after it by opening up that floor which means bath remodel a trench in the bathroom and open up and replace the pipe and then remodel the bathroom and I tell you if you kind of go that far you're going to be within 3 feet of this I'd probably get rid of the house trap too because then at least with all that brand new it'll pitch properly it'll vent properly and you have the ability to actually clear the drain in the future should you need it a big job it is don't shoot the message I'm sorry well I really appreciate you coming and helping us identify the problem and now we'll work on fixing or not in front thanks for you thank you you know you're not always the bearer of bad news you have some good news back in Oh - that was a long time ago now these plumbing stories are hard to see when we're out in the field so I made a little mock-up to help understand what's going on inside all right this is made out of PVC it's not exactly to scale but anyhow has a main drain and a main vent a main stack that goes out completely out through the roof and we essentially saw that with the clean out of the basement is not going up it is made out of that material at the cast iron in this case okay this is just PVC but next to it there's always a separate stack and that's called the vent stack okay and all the systems have to work together so in the case of this building this is represents underneath the toilet on the second floor right and this is the lavatory in the second floor now when you flush the toilet a big slug of water comes down and it's going to push down here it comes right here but there's already air inside this pipe that has to get out of the way somehow and compress this air so now normally it might push that air ahead and put it right out into the sewer right but we have this house trap right here that acts as a resistance point air can't go by the water seal that's inside the trap right so we'd love it to go right here up through this branch because this represents the basement toilet right here here's the basement laboratory yeah this is called the wet vent event that continues up but this whole pipe is we determined in the field had settled so much that if I was to look at this fitting right here it might look like this so it's half filled with more than half filled with water which means the vent is completely blocked because this is actually smaller than diameter rigged like a raft lot right so so now we've got a slug of water on this side right mostly like a water on this right so now with that slug of air that's here being compressed has no other choice it has to go somewhere except to push this way up underneath that basement toilet and bubble up through that water seal in the toilet and every time it bubbles through you're going to get that sewer gas so this is basically sewer gas that was in the pipe that's right and once it bubbled up he got that smell he got that balance neither place to go you have to have properly vented fixtures in the house for every plumbing fixture right well you know what this tells that story goes very well I hope so cool great investigation work Thanks [Music]

Channel: This Old House

Views: 1,619,811

Rating: 4.8395543 out of 5

Keywords: This Old House, Ask This Old House, DIY, Home Improvement, DIY Ideas, Renovation, Renovation Ideas, How To Fix, How To Install, How To Build, Episode, TV Show, plumbing, Richard Trethewey, heating, clogged drain, high tech equipment, advanced diagnose, plumbing drain problems, plumbing 101, plumbing basics, plumbing tricks, house plumbing system, how to plumb a house

Id: rVpbmHl9Mpc

Length: 12min 0sec (720 seconds)

Published: Sun May 14 2017