How To Rig a Gray Water Drain

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Running Out Of Time

The camp trailer’s gray water drain should have been rigged last summer. Here at our off grid acreage, we had an open pit with, sometimes, enough water sitting in it that occasional field mice and the like were at risk of drowning. Sometimes more than risk; a few times, I had to grab the shovel and “skim” small bodies from the water’s surface. We needed to rectify that situation ASAP.

Unfortunately, Pam and I were forced to survive the summer on–as my father used to say–“bacon and beans and mighty little bacon”. There was no money for necessary drainfield supplies and/or materials, so we did what we had to do..and waited, toughing it out day by day. Then, when our financial situation suddenly improved in late August, other priorities intervened.

But now it’s time. The home I’m building is far enough along that I dare take a brief intermission to construct a gray water drain for the camper. The new house has no floor, but it does have a roof. The overall exterior shell isn’t quite done; there remains a coat of stucco and a drainage trench to do. However, it’s not quite warm enough yet for the stucco, and the trench can wait a day or two. Eliminating that gray water pit cannot; a new spring’s crop of kangaroo rat babies could begin wandering around the premises any day now. So….

Good enough; the house building project can be put briefly on hold.

Good enough; the house building project can be put briefly on hold.

The two kangaroo rat babies in the gray water pit, which was fortunately bone dry the night they tumbled to the bottom. (We raised and released this pair, see "How To End Up with Pet Kangaroo Rats" in the Critter Index.)

The two kangaroo rat babies in the gray water pit, which was fortunately bone dry the night they tumbled to the bottom. (We raised and released this pair, see “How To End Up with Pet Kangaroo Rats” in the Critter Index.)

The Barrel And The Bottom

The first step (since we already had a pit of sorts) was to bail out the standing water. We’ve had a lot of rain out here in the desert this winter. The pit was over half full, which meant bucketing out about 100 gallons worth of muddy stuff. Then nothing but mud. In this particular spot, you can get water to drain from about the first three feet of depth. Below that is a layer of caliche which is virutally impervious to water; we’ve seen the pit “hold” at nearly the same water depth for days at a time.

By far the greatest challenge during this digging process was the simple fact that wet mud with high clay content will stick to the blades of a clamshell digger or a shovel like crazy. I had to literally scrape the mud from each blade with a sawed-off shovel handle…every time. That doesn’t make for a lot of speed. Because of that extreme snail’s pace and various deadlines a-looming (such as dark coming on, for one), I decided to “cheat” some on the hole’s depth. More about that in a minute.

Getting the mud to leave the clamshell jaws turned out to be a job in itself.

Getting the mud to leave the clamshell jaws turned out to be a job in itself.

Bucket after bucket of mud, clearing out the bottom to get enough depth for the barrel.

Bucket after bucket of mud, clearing out the bottom to get enough depth for the barrel.

Not deep enough; had to go down nearly another foot.

Not deep enough; had to go down nearly another foot.

Just about ready. The bar across the pit-top allows for accurate depth measurement.

Just about ready. The blue barrel, awaiting its turn.

The Blue Barrel

With the hole/pit ready, or at least as ready as it was going to get, it was time to prepare the “drain barrel” for insertion into that muddy mess. We had on hand a blue 55 gallon polyethylene drum I’d ordered via the Internet some time ago. For ease of handling, my preference is the type that has a separate lid that fastens to the barrel itself with a metal clamp ring.

Ordinarily, a whole bunch of wholes–I mean holes–are drilled all over the barrel, everywhere but the top, and definitely including the bottom. In this case, though, the bottom was not to be drilled because I’d decided to just smunch the barrel right down into that pit-bottom mud. The usual gravel layer below the barrel would not exist; hence no holes in the bottom. All drainage would be through holes in the sides only. With the minimal amount of water draining from the camper at any one time, that did not present a problem. (We wash dishes and pour out extra coffee in the kitchen sink but shower elsewhere, so….)

Drilling the holes.

Drilling the holes.

 View from the inside.


View from the inside.


"I'm ready to rock; lid me!"

“I’m ready to rock; lid me!”

 One hole, close up and personal.


One hole, close up and personal.

Preparing The Lid

There are different ways to rig a drain pipe to a drain barrel. For our survival cabin in Montana (1999-2002), a 1 1/2″ hole was drilled near the top (but on one side, not actually on the top) and a PVC pipe with collar screwed-and-glued firmly to the barrel. That could have been done here as well, but a simpler method suggested itself during my browsing session at Home Depot. They had 45 degree collars designed for use with toilets. The light bulb came on in my evil genius brain, and we were in business.

On the top of the lid (after removing the lid from the barrel), the larger screw plug was removed and stored (not discarded; you never know what’s going to come in handy). The “toilet collar pipe” had six ready made holes. Half a dozen drill-hits later, so did the lid. Then it was a simple matter of bolting things together and clamping the lid back in place on the barrel…and we were good to go. Had it been necessary to ensure a leakproof seal, that could have been done with a chunk of stray inner tube or some such–or even a commercial gasket of appropriate diameter–but leakage (if any) wouldn’t matter in this case. Everything will be permanently beneath several inches of gravel with more gravel all around, so…who cares?

The lid, sans barrel.

The lid, sans barrel.

Sans plug.

Sans plug.

The toilet collar.

The toilet collar.

Collar mounted on lid.

Collar mounted on lid.

A look at the underside.

A look at the underside.

Lid assembly re-clamped to barrel.

Lid assembly re-clamped to barrel.

In The Hole And Good To Go

Hey, we are having some fun now! The steps:

1. Drop “prepared” barrel into pit and “smush-turn” it down into the smooshy clay gumbo at the bottom. Oh, the lowest hole you drilled is now still 1/4″ above the highest mud level? Good. Very good.

2. Shovel in enough gravel to stabilize the barrel, then start dumping the stuff by the wheelbarrow load until things are locked firmly into place, stopping while there’s still room to work with the top-mounted pipe.

3. Get out the ABS pipe, primer, and glue. Assemble elbows, pipe pieces, and couplings–using the mini-trench already there as a place to lay the pipe–until the drain outlet for the camp trailer is reached.

4. Glue the from-the-barrel pipe coupling to the camper outlet. Oh, wait–they don’t fit? Okay, use the inside of a 3″ piece of ABS pipe to go outside the camper outlet pipe…huh. Still a little sloppy? Even gobs of glue don’t help, probably because the trailer pipe isn’t ABS pipe? Hey, no big–ever heard of duct tape?

5. Have wife run water to test the marvelous new system. Discover there’s still a slow–very slow–drip, but it’s not coming from the parts you assembled. Even without the duct tape, those came out watertight, miracle, miracle. No, it’s coming from the ancient, worn out connection between the snap-on trailer drain hookup-thingie and the pipe to which it hooks. Oh, okay….

6. Fill in the mini-trench (as well as the entire pit around and above the barrel) with gravel–actually 1 1/2″ diameter leach rock, but gravel is what we call it.

Now that tiny, slow drip has been rendered irrelevant. At peak usage times, it’ll deploy, what? Maybe a cup of water in a 24 hour period? And all into a rock-filled trench….

Good enough. Never mind that about half of the gravel had to be moved after dark. The deed is done.

Into the pit!

Into the pit!

The smooshy muck at the bottom.

The smooshy muck at the bottom.

Half the gravel added and the piping begun.

Half the gravel added and the piping begun.

The snap-on drain fitting that will never be completely watertight.

The snap-on drain fitting that will never be completely watertight.

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Fully piped and ready for the remaining gravel.

Fully piped and ready for the remaining gravel.

The final load of gravel--not quite full. Our former housemate filled these until they could hold no more...and threw out his shoulder.

The final load of gravel–not quite full. Our former housemate filled these until they could hold no more…and threw out his shoulder.

Duct tape closeup.

Duct tape closeup.

Where once there existed a water filled pit dangerous to small wildlife, now only level gravel shows.

Where once there existed a water filled pit dangerous to small wildlife, now only level gravel shows.

2 thoughts on “How To Rig a Gray Water Drain

  1. Any chance someone could answer some questions??
    1. I read in some other designs that the barrel itself was being filled with gravel Is there a benefit or reason for one or the other? Also, do you think there is any smaller method for just one sink drain for one person? And Does the gravel have to go all the way to the top of the ground in the pit or could you place soil on top and plant grass? (Would the soil seep in and clog the drain system?) Thank you for any thoughts on this! Best, Seal

  2. Sure thing–and your questions are good ones:

    1. Filling the barrel with gravel makes the barrel stronger, less likely to collapse precipitously–as ours did just recently (spring 2015), but only because my wife’s son backed the heavy camp trailer tires right out over the top of it. (We’re no longer using the trailer.)

    2. Leaving the barrel empty does make it weaker…but it also leaves more volume available for a water dump before it has to drain on out of there.

    3. Sure, you could use a smaller container for a one sink, one person situation–a 30 gallon drum or even a 5 gallon bucket (if it was a strong enough bucket–some of the paint buckets might work).

    4. It is sometimes possible to cover the installation with topsoil (and grass)…depending on the soil and climate conditions. We installed a similar gray water drain for an off grid cabin in Montana in 1999, using a steel 55 gallon drum rather than plastic. That drained our full sized bathtub (we had no sink) perfectly for the 3 years we lived there. But down here in southern Arizona, the clay soil–while it never did bother the drain barrel illustrated on this page–totally clogged up a similar installation connected to the washing machine (located in a separate shed) in nothing flat. I believe the difference had to do with the much greater amount of runoff water during monsoon months that hit the one spot. The trailer drain, on the other hand, was luckily situated.

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