31 Oct Greywater, what it is and how to use it:
by Sergio Scabuzzo courtesy of Messenger Mountain News
During the many conversations I’ve had on the subject of greywater, some questions come up often enough that I feel they should be addressed. These range from system design, existing/failing systems, the disposal of greywater, and it’s legality. In writing this, my hope is to clarify some possible misconceptions on the subject. So, without further ado, let’s get to it! Spoiler alert: It has been legal in California since 2009.
On the subject of greywater, some questions come up often enough that they should be addressed. These range from system design, existing/failing systems, the disposal of greywater, and it’s legality. Hopefully this article can help clarify some possible misconceptions on the subject. So, without further ado, let’s get to it! Spoiler alert: It has been legal in California since 2009.
What, exactly, is greywater?
As soon as water goes down a fixture’s drain, it becomes greywater. This excludes water from your toilet, kitchen sink, dish washer, or any water containing dirty diaper wash, harsh chemicals, paints, solvents, etc. Greywater is not potable but is perfectly fine for watering plants. There are a couple of things to keep in mind when doing this so as to keep the system legal and respect our ecosystem. I’ll go over most of these here…
What kinds of systems are there?
Laundry to Landscape:
These are the easiest to get going as there is no requirement for a permit and they are quite flexible during installation. They work by using the washing machine’s pump to push water to the landscape. There are limitations to this as the small pumps can’t push uphill and shouldn’t go much farther than 50 feet, unless going down slope. Materials include PVC pipes, PolyEthelene tubing, and a diverter valve to send water towards the landscape or septic system.
This system does need a permit; it involves cutting into the existing plumbing to separate and redirect greywater towards the landscape. Also, the plants to be watered must be down slope from the greywater source as Branched Drains rely solely on gravity. As the name implies, this design works by progressively splitting the pipes in two. Thereby forming a branched shape. Materials used are ABS rigid pipe, a diverter valve and ideally an actuator (electric motor) mounted on the diverter to remotely switch valve positions. Usually the valves are in the crawl spaces, you don’t want to go under there to switch it before a shower.
Great for pushing greywater up slopes and very versatile, these systems can do a lot but also cost much more, are more complex and are quite a bit harder to get permits for. The greywater flows into a transfer tank with an effluent pump inside and emptied shortly after. Greywater should never be stored for more than 24 hours as it will become septic. The catchment area of the system, inside the home, is the same as a Branched Drain. The transfer part of the system, in the landscape, resembles a Laundry to Landscape’s.
This is not an exhaustive list; these are only some of the most common and functional systems we know about. For more detailed information visit www.greywateraction.org/greywater-system-examples
How do we water the plants?
After the systems collect and divert greywater to the landscape, the journey is not over. We still need to get the water where it will do most benefit, the plants themselves. This is done by sending the greywater to mulch basins next to the plants. A mulch basin is a trench, not usually deeper than 18” and about as wide, filled with wood chips. These wood chips, or mulch, act as a biological filter and also help keep the greywater away from animals, mosquitoes, and humans. The greywater exits into a standard landscaping valve box so roots don’t clog the outlets. All this is located near the root zones of the plants, so they can easily get access to it. A word of caution; greywater has lots of nutrients that plants benefit from, but these same nutrients could easily harm our ecosystem. Please never use Greywater for spray irrigation, allow it to pond, runoff or be discharged directly into or reach the creek.
What types of products should be used?
Because the greywater will be going to your plants, we want to make sure there is nothing in the water that can harm them. Ideally the products don’t contain SALT, BORON, or CHLORINE.
Some good products include:
ECOS, Biopac, Trader Joes, Oasis, Vaska, Aubrey Organics, hydrogen
Don’t use sodium based water softeners as the high level of salt will damage your plants in the long run. There are potassium based alternatives out there.
Is it really legal to have a greywater system?
The answer is… It depends! If you follow the California Plumbing Code, then it is 100% legal. If, like anything else, you don’t follow regulations and/or don’t get a permit if needed; then it is illegal.
Basically, for any system outside of Laundry to Landscape, you need to get a permit from the Department of Building and Safety. Also a plan review needs to be obtained from the Los Angeles County Department of Public Health.
Sergio Scabuzzo is one of Greywater Action’s educators, an active member of Topanga Creek Watershed Committee and currently lives in Topanga Canyon where he spends most of his free time talking about water harvesting, sustainability and plants.
For more information contact email@example.com or join the forums at www.greywateraction.org/forum