Residential greywater options, pros and cons

June 14, 2017 10:22 AM

We'd like to set up a greywater system of some sort, but I'd like to hear what other people are using and liking, and issues they've encountered.

We stayed with friends who flushed their toilets with water from a bucket in the shower, and that sort of simple water conservation is appealing, if a bit arduous. Looking around, there are a wide range of systems and solutions to reuse water in the house, from whole-house systems to kits focused on reusing water in a single bathroom.

More context: we're a family of four, with two adults and two kids under 6. We live in a high desert (New Mexico, in Rio Rancho, an extended suburb of Albuquerque), so we have some landscaping that we water, but no lawn. We're on city water and sewer, we take showers and baths, and have our own washing machine and dish washer. Currently, we don't specifically use any biodegradable soaps or detergents.

At this point, a whole-house system would probably be too expensive for us right now, especially compared to collecting shower water to flush toilets. The one problem with this bucket system is that this requires manually pouring water in the toilet, either in the tank as it refills after a flush, or in the bowl to trigger a flush, neither of which our kids could do on their own, and it's a small ask for guests, so that's why I'm interested in more automated systems, or at least some way to pre-fill a larger volume of water to flush toilets, if that's the only thing we do.

posted by filthy light thief to Home & Garden (6 answers total)

Any system you may install will have to follow New Mexico gray water regulations.

Here is a pamphlet (PDF) on gray water guidelines and suggestions. The pamphlet includes two ideas of where to input diverted valves into your current set up, which could be an option for you. Maybe you could divert shower and sink water into your toilet rather than use buckets?

I have never used a gray water system, but I do know that soils in NM are already highly alkaline, so adjusting the pH of gray water would be important before using the water for landscaping.
posted by BooneTheCowboyToy at 10:43 AM on June 14, 2017

This looks like a basic system that automates the things you're interested in. But, cost is considerable, you have to buy the system, plus have a bunch of plumbing done, and there is ongoing cost of electricity for the pumps involved. (Can't find cost info but I'd estimate $3-5K depending on installation complexity. There are others on the market such as. )

This is a real simple gadget you can install on top of your toilet. It recycles the water from washing your hands and uses it for the next flush. It's $130 at Home Depot.
posted by beagle at 1:07 PM on June 14, 2017

An old housemate of mine installed some sort of simple motorized pump to pipe his shower water up out the bathroom window and down into a barrel, where he stored it for use in the garden.
posted by aniola at 1:44 PM on June 14, 2017

First step when contemplating doing anything at all with greywater re-use is to accept Art Ludwig as your personal saviour.
posted by flabdablet at 11:14 PM on June 14, 2017

some sort of simple motorized pump to pipe his shower water up out the bathroom window and down into a barrel, where he stored it for use in the garden

Error: Pump enthusiasm
Error: Storage of greywater
posted by flabdablet at 11:24 PM on June 14, 2017

For what it's worth, when I renovated my own bathroom I based the design on a clawfoot cast iron bathtub and a shower head coming down from the ceiling, then kept the bath drain as high as I could; the U-bend for the drain is actually just an elbow under the bath and a flexible coupling leading to a horizontal drain line though the wall, so the surface of the water trap is only about 20mm down from the grating in the tub.

I have an arrangement of reconfigurable pipe sections outside the bathroom wall that I can use to divert shower and bath water down one of several distribution pipes. One of these runs around the side of the house toward the front lawn (which is actually on the slightly-uphill side of the block). Another runs downhill, with branch lines that visit a couple of raised garden beds, ending up at a 40mm to 20mm reduction joint that feeds a 15m flexible sullage hose (thick walled straight hose, not the flimsy corrugated type). The end of that hose gets dropped into the mulch basin around whichever backyard tree looks like it needs it the most.

Also included in the pipework is an overflow bypass to sewer, so that if the bathtub is completely full and the plug gets pulled, the tub still drains at full speed even though the sullage hose is in no way capable of letting it do that.

This arrangement has been in place for ten years, it's still working well, and our back yard stays green all summer even though we never, ever run a sprinkler on it.

I've made no attempt to re-use laundry, kitchen, handbasin or toilet water.
posted by flabdablet at 11:37 PM on June 14, 2017