My greywater story

Ten years ago I created a compost toilet and grey water system so that we could have large numbers of guests without taxing our existing septic and spring-fed water systems. We were planning a wedding and my daughter was willing to have it on our picturesque front lawn IF we didn’t have those awful blue plastic outhouses for the guests. Soooo… a project was born. (We just had another wedding a couple of weeks ago… some shots are in recent posts).

I’ll talk about the compost toilet in another post… but with California under water restriction according to one of the Tweeters I follow, I thought I’d quickly mention what I did and what I learned from it.

My personal greywater wetland

My personal greywater wetland

I ran all the sinks and washing machine for the building into a simple 2 inch pipe… Made sure it had at least an inch drop in ten feet, and ran it about 150 feet to a suitable spot. I rented a backhoe and dug the trenches myself, and scraped away the topsoil down to clay for the wetland… about 10 feet wide and 50 feet long. I lined the area with 7mil Milar, and then laid the termination of the pipe about 5 feet past the edge of the area. I split the end of the pipe into 3, and drilled holes along the way, capping it at the ends. Then I brought in a load of 4-inch river rocks, followed by gravel and sand, and replace soil around the edges. My thought was that the water would flow out into the gravel, etc.

For 9 years, it worked flawlessly. By the end of the first year, cattails had established themselves, with frogs and flowering lily pads not far behind. My mom, who lived in the garage we converted into that house, enjoyed it and followed our rule of not using chlorine bleach, detergents, etc. Just ivory soap… which the cattails converted into clean water.

A year ago, the system backed up. We excavated the end of the pipe and found that the three prongs were filled solid with black sludge.

All 3 prongs were completely plugged

All 3 prongs were completely plugged

It had then backed up all the way up the 150 feet to the house.

Closeup of the sludge

Closeup of the sludge

This time, I used a new kind of termination … expanding the pipe to 4 inches, into a wye, and then putting both sides of the wye into two 10-foot lengths of “Quick4 Leaching Chambers”.

Quick4 Leaching Chambers

Quick4 Leaching Chambers

They’re very cheap, available at plumbing supply stores. They come in 4-foot lengths, and snap together with a pivot like sausages. You lay them on the gravel, cover them with a filter cloth, and then backfill the sand and dirt over them.

Here’s the main takeaway: many plumbers consider kitchen waste “black water” along with the obviously black toilet effluent. The reason is that the grease and food fibers of kitchen sink drainage quickly turn black, and to keep it from clogging, a settling area is advisable. This is a pain… it involves a tank, a cleanout, a baffle to keep the solids from spilling over into the exit… practically a septic system. In the end, I decided that my simple leach system would survive for 40 years or more without adjustment simply by using the Quick4 leaching chambers. So I didn’t replumb my kitchen sink. But if you live in the suburbs, already have a standard sewage pipe exiting your house (or a full-scale septic or aeration system in place) and just want to create a small grey water system for your back yard garden, I’d advise avoiding the kitchen sink drain… let that go into the sewage system, and just divert your showers and hand sinks into the greywater system. You’ll feel good knowing that the water you’re washing in ends up in your garden.

If you want it to go into a decorative pond, be sure to let the natural cleaning power of cattails and bulrushes clean it first.

Disclaimer: for reasons that escape me, none of this is considered “code” as far as I know. Perhaps in California some greywater systems have been approved. But in my part of the country, the authorities are at least 30 years behind the times. We’re all going to hit a wall when the water shortages hit.

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