Repairing a Shower Drain

David Trammel's picture

One of the things a handy Green Wizard will need to learn, is how to make repairs to critical infrastructure like your home plumbing.


Last Monday, after taking a morning shower in preparation for work, I went downstairs to grab my uniform. The company supplies us with uniforms, and the uniform company will wash them for you, but I always seem to prefer washing them at home. The duplex I live in, like most homes in Missouri have a basement. Its usually used for storage and the place where your appliances like your washer and dryer live.

As soon as I stepped off the stairs, I stepped into water. Not much just a wet floor. That's not supposed to happen. On further investigation, I discovered this:

The pipe from the shower drain had corroded so badly that it had separated from the P-Trap. That's the larger section of pipe to the right of the picture. The top of it, has a access lid, and if the pipe gets stopped up, you can open it to clean it out. If you look under any sink in your home you will see a similar set up though you mostly have to just remove the plastic U on the bottom now to clean them (or recover that ring you accidentally dropped down the drain.)

These traps are important because they prevent dangerous gases like methane that rotting sewage and food scraps generate, from escaping up your drain pipe and into your home. That downward loop fills with water and prevents the gases from passing.

I suspect I am looking at original piping installed when the duplex was first built, which I believe was in the 50s or 60s.

Yes, that's my main sewer embedded in the concrete dividing wall between the two apartments, lol. I was pretty amazed when I saw that too, when I first moved in. Why the builder didn't do two separate stacks and then do a Y-Junction in the floor, can only be caulked up to trying to save money.

Another sign that this is original pipe, notice the pipe pointed out by the right arrow in the picture. That's a flexible lead pipe.

(The left arrow points to the P-Trap)

I knew I had to proceed cautiously with this repair. Over time, lead can grow brittle and if I wasn't careful the weight of the P-Trap could snap it or damage it in a way beyond my ability to repair. The weight of the P-Trap is probably a contributing factor in the drain pipe separate, or should I say the P-Trap separating. Once the drain pipe had become sufficiently corroded and weakened that big copper weight pulled it apart.

My plan then was to remove the left section of the P-Trap pipe where it joined the end of the drain pipe and replace it with a plastic elbow and pipe, then join the existing pipe to the new section with rubber sleeves. This should do for now, though eventually I'll need to have the lead pipe removed from the main sewer pipe and new plastic pipe installed.

Here's what I needed to do the repair.

Visiting my local family owned hardware store, I picked up one plastic elbow, one 12" connecting straight pvc pipe and two rubber couplers. I actually took this picture after I had cut off the two pieces, you can see them laying on either side of the pvc connector pipe.

BTW, here is a good tool to have in your tool box.

These are "vernier calipers", and are a great tool for measuring things. Simple ones can measure in about a 1/ 32nd of an inch by sight, more expensive and precise ones can measure accurately to one thousandths of an inch. There are three ways to measure, "Outside, Inside and Depth". They are great tools when you are dealing with round objects like pipe and tubing, hence their usefulness in this situation.

Measuring the drain pipe and the P-Trap pipe I found they were 1 1/2 and 1 9/16th of an inch in diameter respectively. With that info I visited the hardware store.

(I love family owned local hardware stores, they always have the oddest and most useful things, and their staff are knowledgeable and actually want to help you.)

The clerk easily found me a 1 1/2 (or 1 1/4) inch elbow. The elbow can be used for either diameter, by selecting the appropriate gasket. In the picture of tools above, notice the thin clear silicon gasket and a slightly thicker one. Threaded plastic nuts come with it. You put the nut on the pipe, then put the silicon gasket on it. As you tighten the nut to the elbow, it presses the seal into place. That's the short section of plastic pipe in the foreground of the picture, and will be used to connect the P-Trap copper pipe to the elbow.

The 12" connecting pipe has a short section which flares out and will allow the copper drain pipe from the shower to seat inside of it. I didn't need all 12" but I will need a short section to join the lower P-Trap copper pipe to the elbow.

I didn't want to risk the up and down motion that would have resulted had I used a hack saw, like normally I would have, to cut the copper P-Trap pipe. Also the space was limited, so I used a Dremel rotary tool. That's the small hand tool with a cord to the right in the picture of stuff. I used a ceramic cut off wheel.

Let me just say, that this tool is a "must have" for Green Wizards. It has dozens of specialty bits and cutters, and I find myself using it continuously for projects. There are cheaper versions out there, but buy quality when you get one of these.

First thing I want to do is drain the water that is in the P-Trap, so I used the Dremel to cut a slot in it until water started dripping out. The rubber coupler is long for this installation so chose to leave just enough that the pipe clamp on the rubber couple would have enough copper pipe to seat well and hold. I had to repeat my cut until I got it to the bottom of the pipe and drained all the water.

Then I cut the end off the shower drain pipe. Here I went quite a ways up the pipe, hoping I would get past any corrosion and a weak walled pipe.

Once I began assembling the new parts, the only minor problem I had was the short expanded section of the plastic pipe, that I fitted onto the shower drain pipe, was a little tight going into the rubber coupler. I unscrewed the pipe clamp completely and then worked the plastic pipe into the rubber with the help of a little olive oil from the kitchen.

The pipe clamps were hand tightened with a screw driver. They can be further tightened with a socket wrench, their heads are shaped like nuts and hexagonal but I didn't feel excess tightening would be advisable given that the pipe had possible corrosion. The same with the plastic nuts on the elbow.

Once I was done, I put a plastic 5 gallon bucket under it to see if I had any leaks. I'll check it after my next shower and the again in a week.

Here's everything assembled.

That's my repair. Cost was about $25US and time about an hour.


Remember YOU can do repairs and fixes, trust yourself.

Sweet Tatorman's picture

Nice photo pictorial!
I totally agree with your position on the virtues of old time independent hardware stores and the usefulness of quality dremel type tools.
A stickler for terminology would note that of your pictured calipers only the top one is a Vernier caliper. The bottom one is a caliper with dial indicator. The later have become so ubiquitous that I would wager that the majority of folks under 50 would not know how to read a Vernier scale. The Vernier scale is certainly a technology consistent with the spirit of this forum as it is about to celebrate it's 400th anniversary having been invented in the early 1600's.

David Trammel's picture

I've always called the lower one a "dial caliper". It wasn't until I bought the mechanical one and the packaging said "Verneer Caliper" that I did some quick reading of the original scale and its use. I can see how it, like the slide rule will be returning in the Future as tech winds down.

I'm old enough to be pre-digital on my calipers, so i have two dial calipers. My work has a precision saw which can do plus or minus 5 thousandth of an inch cuts on up to 5 inch diameter material, so I use the digital caliper they have regularly. Its tested for accuracy.

I still prefer my mechanical dial caliper, it never has a dead battery, lol.

Alacrates's picture

Wow, that is some old-style plumbing, I have never seen a trap like that! Nice tidy repair.

Agreed that the weight of the trap/lead arm (and the downward pressure of the shower water) was what finally did in the corroded copper drain. I would say that arm should probably have some some support. Normally I would hang some coated strapping from the joist just beyond the trap to support the pipe.

David Trammel's picture

I completely missed the thought of doing some supporting wire. I'll do that this weekend.