Washing MachineI set up the washing machine a few weeks ago, using Oasis Design's "laundry to landscape" method, which relies on the pump of the washing machine to move the water. This allows us to send the water slightly uphill, into our backyard "shrub thicket" of blueberries and serviceberries, where a gravity-fed system couldn't reach.
This pipe doesn't work perfectly yet. Despite my efforts to raise up the path next to the garage wall (see the bare dirt in the first picture above), the pipe still dips down before heading gradually upslope to the discharge points. This means most of the water exits through the first couple of holes, and that the last bits of water stagnate in the low spot by the garage wall. I may reconfigure the setup so the pipe still dips to cross the path, but then immediately jumps up and anchors to the black locust trunk visible in the picture above. That would allow a continuous feed downhill to all the discharge points, giving a fairly even irrigation pattern. I can add a joint or cleanout valve or something at the garage wall low point to remove crud that builds up, or drain the hose before hard freezes.
The wetland resides in an old fiberglass jacuzzi I got for free from craigslist years ago, about 6'x4'x3'. I plugged up all the holes in the tub using rubber patches and 100% silicone caulk. In 2007 or 2008, I dug a big hole in the front yard, just across the main path running by the north edge of our house, and buried the hot tub pretty close to level, but making sure it tipped slightly away from the house, so the overflow would drain into the adjoining garden bed. I made the top of the tub level with the path, or perhaps even slightly lower. Over the years we've built the paths up several more inches, so the tub is now uncomfortably low. Back then, I wanted to make sure we could gravity feed from the house drains into the tub, and we did not yet have plans to lift the house. Had I known then we'd wind up raising the house 3', I'd have made the tub higher. Woulda saved me some digging, too!
At some point I buried a bath tub (again, free from craigslist) to receive the overflow from the wetland. I leveled the new bath tub to overflow away from the house again, to keep moving any excess water further into the garden bed area. I tried to strategically compact dirt to control the wetland overflow location, and to use a scrap piece of marble slate to catch the water and carry it down to the new tub. Unfortunately, lots of water seeped through the dirt and was lost to the soil in the surrounding paths. The marble slate wasn't quite long enough to properly reach between the tubs, so we lost yet more water. All in all, probably 20% or less of the input water made it into the second tub.
Furthermore, the water in the wetland stagnated somewhat, smelling a bit nasty when we pulled it up from the bottom of the tub. When we poured graywater into the tub, it followed the path of least resistance, mostly across the surface of the tub straight to the overflow area. So we were concerned that the plants weren't having a chance to purify the water much. We decided to follow the method described in Toby Hemenway's Gaia's Garden, and fill the wetland with gravel and baffles. The rocks in conjunction with the oygenating plant roots supposedly help create a combination of aerobic and anaerobic sites for microorganisms to live, eating the other microorganisms and solids coming in with the graywater.
Our friend Nat loaned us a concrete mixer, and helped me make a run with his trailer to buy half a cubic yard of 3/4" gravel. We held a work party and used the mixer to wash off the rocks, to minimize the dirt we'd be introducing into the system. (Dirt will eventually clog up the spaces between the gravel and dramatically slow the water flow through the wetland.) We placed a vertical inlet pipe into the end closest to the house, and another vertical pipe near the overflow area; both pipes have many holes drilled into them to allow water flow. We placed larger river rock (~1.5"-3", a byproduct of my excavations under our house) around those pipes. I based this decision on the literature I read; I think it helps with allowing optimal water flow, or perhaps it helps trap the gunk coming in from the house without clogging up the smaller rocks?
We filled the rest of the tub with the smaller gravel, building up vertical baffles using sturdy scrap plastic (mostly square lids from 4 gallon buckets). The baffles force the water to take a long, circuitous route right, then left, then right, then left through the wetland, giving the plant roots the most time possible to clean the water before it finally overflows at the far right edge of the tub.
I assume in the winter, with the wetland plants dormant, we get very little treatment, so I'm careful not to use the water from the second tub for anything where contamination may cause problems. In the summer I feel comfortable using the water to irrigate, rinse roots, wash my hands, etc. However, we haven't done any water quality testing, which would be necessary to establish how well the wetland actually treats the water.