How to Plumb a Tricky Twisty Bathtub Drainpipe into a Smelly Stinky Sewer Pipe

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In our mirror image bathrooms at the Border Fort, I was able to plumb the flush toilets long before we could afford to add a bathtub or, for that matter, a bathroom sink. To prepare for the day, however, I’d included a Y fitting in the sewer pipeline, added a bit of curved extension, and capped off the “branch” that would eventually receive the bathtub drainpipe.

Which meant that today, when it was finally time to hook up that drainpipe. a number of steps would have to be followed. The branch on the Y ended up on the wrong side of the sewer pipe, for one thing. I’d prelaid most of the gray water pipe while building the box floors in the bathrooms, but the exit pipe (from the bathroom) was going to have to cross under the sewer pipe, swoop back up, and hook into the Y.

Clear as mud?

Hey, not even. But, as they say, a picture is worth a thousand words.

Take a look or two.

The setup prior to today's effort.

The setup prior to today’s effort.

Truth? I’d been ducking this part of the job for a while. But all good things must come to an end, or so the pessimists say. Time to get at it, mostly because my wife was off running errands with her son. I had the house to myself.

Which was important why?

Two reasons:

1. There might be a lot of cussing going on. With Pam clear of the building, I could let ‘er rip if need be.

2. When I cut into that Y arm, it was going to give the sewer line (and thus the sewer gases) free access to the entire home. The cats and I could handle that. Pam…maybe not.

The first step, however, was fairly simple. A couple of 90 degree fittings were coupled together at an “odd” angle, simply because the intuitive curves needed to make this thing work required that. Then the two-fitting combo was coupled to the bathtub drainpipe.

Now we had the outlet aiming across (and beneath) the sewer pipe…sort of.

The first two fittings coupled together at the intuitively needed angle.

The first two fittings coupled together at the intuitively needed angle.


The mini-combo coupled to the bathtub drainpipe, aimed across (and beneath) the sewer pipe at a bit of an angle.

The mini-combo coupled to the bathtub drainpipe, aimed across (and beneath) the sewer pipe at a bit of an angle.

For a lot of plumbers, piping is a definite, quantifiable science. Nice, long piping runs with crisp, clean sweeps and angles. Good stuff. Beautiful stuff, if you have the eye to appreciate it. But for the less structured, just-make-it-work DIY (Do It Yourself) redneck, plumbing can also be–at least sometimes–pure art.

This was such a case.

Readers are likely to wonder, Ghost, why on Earth didn’t you put that Y branch on the other side of the sewer pipe in the first place? The answer is simple: When that sewer line was laid, I didn’t picture the entire end result in perfect detail. Didn’t realize the BIG Y that branches the 3 inch pipe over to Pam’s bathroom (from mine) would end up blocking the hole through which I’d planned to run the smaller 1 1/2 inch line.

Could have chopped the sewer line, flipped everything, and reassembled, of course. Wasn’t about to back up that far, but could have…in theory only.

Anyway, back to the project: There was an additional challenge in that the Y arm wasn’t perfectly level but rose at a slight angle toward it’s capped end. That rise meant that any straightforward series of 90 degree elbow fittings was doomed to failure. At some point, two pipe ends were going to be trying to mate without being lined up properly.

Enter, as we’ve been stressing here, the A & I team: Art and Intuition. It felt like such-and-such a combination of various elbows would do the trick…but only time would tell.

So, this time a fancy serpentine 3-elbow combo was coupled together…and the capped Y arm was sawed off short to receive one end of that combo.

The sewer gases weren’t bad at all.

The sewage itself, however, was another matter entirely. First, the cap plus just a couple of inches of pipe was removed from the arm. Poop in pipe. Poop on saw blade. Gross! Ew-w! Icky poo!

Took the partially filled end cap piece outside, whipped an underhand fastpitch softball throw, slung the yucky thing off 100 feet or so in the weeds. Then went to wash my hands before returning to work. Might have to pick that cap up later, but at least the “stuff” would be long dried by then. Ghost chips, good for campfires out on the open prairie.

Drug the saw blade through a pile of dirt a few times to clean it.

At that point, it was time to “fool around” with the 3-elbow combo I’d put together, hold it in position, see if adding one more elbow at either end could make the the whole thing come together.

Nope.

&%#$!!

Crap. Literally. I was going to have to saw off a few more inches of that Y arm. More poop in pipe, no doubt. Still not too stinky, not too smelly, and…well, I had it to do.

Surprise. Much less sewage this time–not even enough to show up on the saw blade. But there was–uh-oh–water. Not a lot, as it turned out, but enough to be kind of scary for a minute there.

Okay. Intuitive fiddling with serpentine combo (plus an additional 90 degree elbow at one end) indicated the arrangement should work.

The three-elbow combo, two 90's and a 22 1/2.

The three-elbow combo, two 90’s and a 22 1/2.


 At upper left: The partially poo-stained Y arm after the second cut, ready to receive the "combo connector" piping.


At upper left: The partially poo-stained Y arm after the second cut, ready to receive the “combo connector” piping.

With the final 90 degree elbow added to the serpentine, making it a 4-fitting combo, the ultimate test was ready to judge me unmercifully. Could this even be done, ramming a foot’s worth of twisty, tricky piping in between and then over two ends that wouldn’t be much interested in flexing to accommodate the process?

One way to find out. The steps:

    1. Apply cleaner and then ABS glue at both ends; this must happen all at once or not at all.

    2. Bless this “slam-jam situation”.

    3. Take a deep breath and pick up the multi-fitting combo.

    4. Shove-twist the 22 1/2 degree end in place, twisting while at the same time

    5. Forcing the Y-arm end into place, big time hardcore.

Well, I’ll be danged. Whaddya know; it actually worked!

The final assembly. Whaddya know; it actually worked!

The final assembly. Whaddya know; it actually worked!


After cleanup, with the glue-and-poo catcher plastic ground cloth removed.

After cleanup, with the glue-and-poo catcher plastic ground cloth removed.

ne more thing to do: Check the pipe for leaks and, in the process, load the series of traps with gas-stopping water. It’s unlikely you’ve ever seen a home plumbing system constructed in this way, with the bathtub drainpiple going through a series of ups and downs the length of the bathroom and a bit beyond…but it will work.

Frankly, it has to work. Quickly? Maybe, maybe not; only a full-tub drain test will tell us that, and the tub’s not hooked up yet. But despite the roller coaster and riversnake serpentine effect, there’s plenty of drop in elevation along the way. Plenty of vent air, too.

For now, the open “uphill” end of the drainpipe got its water test: Two gallons of water, and then another two, loaded through a red plastic funnel. Toward the end of the pouring, there was clearly a little slowdown effect; it’s not going to be like dropping water through a straightpipe into open air.

But overall, not bad so far. And when I checked the standpipe later (where the tub drain will attach), there was no water visible in the pipe. Which means the tub water will have plenty of “drop” to help push its gray water downhole when the time comes.

All in all, a great plumbing session. Especially since it was completed seven minutes and three seconds before Zach and Pam pulled into the driveway.

The red funnel.

The red funnel.

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