How to beat an old drum trap

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Q: My 1920s Ravenna home has a slow-running bathtub drain. The sink and toilet do just fine, as do the other drains in the house. I have cleaned the screen that I leave in the drain, and there is no mechanical handle or linkage to be catching hair and slowing the water down. I use a removable rubber plug when I take a bath instead.

I have tried every kind of drain cleaner known to man, and have even run a plumber's snake through via the overflow. The snake stops about 6 or 8 feet downstream.

Wanting to see what the obstruction was, I went into the unfinished basement beneath the bathroom where the snake stops. Looking up toward the tub, I saw a device a little larger than a Coke can, with one lead-colored pipe from the tub leading into it, and another on the opposite side, but higher, draining toward the main sewer drain. It looks original to the home, or at least very old.

This Coke-can thing clearly is the source of my obstruction. Coincidentally, it's located directly over the main electrical panel and has a fitting for a pipe wrench on the bottom.

Could this be a removable clean-out? Can I open it to remove the obstruction? And if so, how do I keep from electrocuting myself or getting a sewage shower — or both simultaneously?

A: Your Coke can is most definitely not drinkable; it is called a "drum trap." Drum traps are used in older buildings beneath tubs rather than the typical U-shaped P-trap you see under sinks, or newer tubs.

As a point of reference, your toilet has an internal trap (also called a trap seal). A trap is a low area in a drain that continually has water in it, thus preventing sewage smells, methane and other gases from entering the home.

In my elementary-school days, I specifically remember gas traveling through water. In the tub. Every time. So naturally, I have doubts about the presumed accuracy of the science here, but let's move on.

So, traps are the most commonly plugged area in a drain. Drum traps are not "self-cleaning" like P-traps. A modern P-trap (theoretically) flushes all the hair, dirt and other debris down the drain.

Drum traps by their very design must be cleaned manually because the pipe feeding it is below the pipe draining it. It is difficult enough to move a clog downhill through a smooth pipe, much less uphill and around a corner.

When the tub runs slowly, don rubber gloves, put a clothespin on your nose, remove the cap and pull all your composted hair and soap scum from the trap. Replace the cap and the deal is done — until it runs slowly again.

Ninety-nine out of 100 times, the clean-out for the drum trap is located in the floor of the bathroom next to, or very close to, the tub. You simply kneel on the floor to do the deed.

Occasionally, the clean-out cap gets covered by a sloppy remodel or flooring job and is no longer accessible. The clean-out for your house for some reason is mounted upside down and accessible from the basement, so maybe the plumber was a sadist.

When you pop the cap, you will get drenched in sewage, and so will the electrical panel, as you point out. I suppose you could configure some elaborate plastic sheeting contraption to protect the electric panel, the walls and the floor, cocoon yourself in a body condom and pop open your little box of stinky, but why?

Every time you get a clog, you will need to go through the same biohazard routine. Not worth it in my book.

Instead, get two helpers and have one stand with a bucket and the other hold the plumbing steady. Take a Sawzall with a metal cutting blade and hack the drum trap completely out.

Cut out all the plumbing from the base of the tub to just past the drain side of the old location of your drum trap. Then add a modern self-cleaning trap and vent. Yeah, you may want to have a plumber do this.

To follow up on another intriguing topic ...

Several weeks ago, I mentioned a cat I found in a new home's crawlspace.

Despite the best efforts of several people for hours, the cat ran, hid very well and was not located.

The builder placed a live trap in the crawl space and baited it with wet cat food. After two more days, the cat wandered toward the food and was trapped and made it out in good health.

Darrell Hay is a local home inspector and manages several rental properties. Call 206-464-8514 to record a question, or e-mail dhay@seattletimes.com. Sorry, no personal replies.