Monday, May 28, 2007

Using a blowbag to clear a slow drainpipe

In our kitchen sink, there is a garbage disposal, which grinds stuff up so it can flow down a 2" pipe into a bigger drainpipe and out to the sewer.

The other day, that 2" pipe got clogged, which by itself would be bad enough -- but we have a shower that shares the drainpipe with the kitchen sink, so it backed up, turning the shower floor into an icky awful mess; I will not show you a photo of it. (You're welcome).

My mission, which I chose to accept, was to clear the drainpipe so that the stuff could flow out, rather than into the shower, and to clean up the mess.

The solution

The basic idea was to find the "cleanout" -- a pipe end I could uncap to clean out the drainpipe. I had to uncap it and use a blowbag to flush the obstruction out.

Uncap the cleanout

To find the cleanout, you have to find the 2" (or so) pipe that the kitchen sink drains into. This 2-incher slopes down to reach the bigger drainpipe. In our case, the cleanout is above the point where the 1" (or is it 1½"?) pipe from the kitchen hits the 2" pipe. I'm going to guess that if you google on "cleanout" and "drain" you'll find a useful diagram or two.

So I found the cleanout and tried to unscrew the cap with a pipe wrench:

Trouble was, I couldn't budge it. I tried putting the wrench on the other way and standing on the end. I tried banging on it with a 3-lb. hammer. I got a screwdriver, placed it against one of the bumps on the cap, and whacked it with the hammer. I got a piece of rigid electrical conduit to try to increase my leverage on the pipe wrench, but it wasn't big enough. Nothing seemed to work, until I remembered that I had a hydraulic floor jack:

That actually worked. If you try this at home, by the way, it's a good idea to put a big sign on the kitchen faucet -- that way, nobody will decide to run the water while you're outside (or under the house) struggling with the drainpipe.

If it's been long enough since your latest flood, you won't have a flood of goop fly out of the cleanout when you get it uncapped. If you're under time pressure, best you put a bucket under the cleanout. A big bucket. A tub.

I didn't have that problem this time around, but it has happened before. You'll want to use a bucket that you don't mind soiling.

What is a blowbag?

Here is a picture:

That was taken after it did its work, but here's the story. Its main body is made of some kind of black rubber. At one end is a brass fitting that you attach to the end of a garden hose. At the other end is some kind of flow restrictor. I fed it into the pipe -- making sure to feed it in far enough -- i.e., so that I would flush the goop further down the 2" pipe, rather than up into the shower or back into the kitchen sink.

In my case, that was about 5-7 feet, so to make sure I fed the hose at least ten feet into the drainpipe. Here's another picture:

(actually taken afterwards, as I was pulling it out -- as if you couldn't tell).

Then I turned on the hose full-blast. The blowbag expanded to the diameter of the pipe, then the "exhaust" end of the blowbag sent pulsating jets of water down the drainpipe. This forced accumulated sludge out of the 2" drainpipe into the 4" line that runs into the sewer line under the street (in our case, the alley behind our house).

I used hot water in the hose, but cold is also OK.

I heard the vibrations in the house, and turned off the hose after about a minute. Then I extracted it slowly from the drainpipe.

My next step was to re-cap the drainpipe and test the flow down the kitchen sink. All was good, so I cleaned up the hose, and the shower, changed, and took a shower myself.

Helpful(?) hints

  • Do this job early in the day if possible. There are many reasons why. From the photos above, though, you can see that I didn't take my own advice. I think I learned of the problem after I got home from work in the evening, but didn't want to deal with it until after dinner. Then I conveniently forgot about it until after dark. That was not so convenient.
  • Take a look around the house for cleanouts, and have at least one blowbag of appropriate size on hand before the need arises. Your spouse and your children will think you're a genius. Of course they'll be right!
  • A corollary: Have pipe wrench(es) on hand that are big enough to deal with the cleanouts.
  • Another corollary: If you don't have a floor jack, have a piece of rigid pipe big enough to accommodate the handle of the pipe wrench. Then you can use the pipe as an extension of the pipe wrench handle. A 3-5 foot pipe (insert the entire handle into the pipe if you can!) ought to give you enough leverage to deal with any sewer cleanout. If not, you may have to pry open your wallet and call a plumber.
  • Be really sure, when unscrewing the cap from the cleanout, that you're turning it in the right direction -- i.e., that you're trying to loosen it, not tighten it. Don't ask me how I know.
  • When replacing the cap, be really careful not to cross-thread it. Don't ask me how I know.
  • Use your oldest, dirtiest, ugliest garden hose on the blowbag. For the reason why, take a close look at the photos above. See how icky the hose looks after doing this job?
  • Corollary: Be sure that you don't mind staining whatever clothes you're wearing. Shoes, too.


Anonymous said...

where can you buy a "blowbag"? (I could not find them at any standard hardware stores (via the internet))

collin said...

I walked into a hardware store and found the drain-cleaning stuff (the "snake"s and "auger"s). Either it was right there, or I asked someone. About ordering it online I have no idea, sorry.

Cheryl said...

Thank you for this post! We found our clean out beneath a 2 inch stucco job, fully involved in very creative stucco. It took 45 minutes to access it with a 5 pound hammer and iron chisel. Colin grabbed both the jacks out of the garage (2 and 4 ton) - I wouldn't have thought of it for years! Lefty-loosey - with daylight moving right along. We've found a lot of similar 'gifts' from that contractor, who has long since moved on, including a 16 head valve job for a 1000 sq ft yard. Between Lowes and Harbor Freight we got the job done.