Survival of the Wettest
January 9, 2008 12:23 AM   Subscribe

Do you or anyone you know make use of graywater. If so, how?

I plan to live a more sustainable lifestyle. I seek anecdotes about using gray/greywater|rainwater. My region (Western Kentucky) experienced a great deal of rainfall recently and I pondered how much non-potable water could have been saved. I currently rent an apartment and am quite limited in my exterior "projects." Within the next year-or-so I should be able to start a more crunchy-granola lifestyle.

I have researched online and subscribe to Mother Earth News and Grit. What experiences can you relate and how do local laws/codes affect you?
posted by bonobo to Home & Garden (35 answers total) 15 users marked this as a favorite
I collect some rainwater and use it to water the plants in my (very) small greenhouse. Aside from gardening with it, I've got no bright ideas.
posted by foodgeek at 12:45 AM on January 9, 2008

I don't feel I have anything to contribute, but I'm very curious about your goals. Are you asking about using greywater for tasks, in place of municipal water supplies? Like, collecting it and rendering it useful for things other people would just use tap water for?

It occurs to me that you can render water usable for pretty much anything by boiling it and collecting the (mostly) pure steam, but since most methods of generating heat are kind of environmentally unfriendly, I'm not sure if that's congruent with a crunchy lifestyle.

I guess all I'm saying is that I'm excited to follow this thread and learn stuff.
posted by chudmonkey at 12:50 AM on January 9, 2008

washing clothes, watering plants and the grounds (they have no grass of course), filling the swimming pool I believe, they may even have it plumbed into their toilets, but I am not sure about this one - the eventual plan is to move beyond gray water and make it potable
posted by caddis at 12:51 AM on January 9, 2008

Best answer: I'm one of six kids, so when we all lived at home there'd be two loads of laundry every day. Mum would run the hose out of the machine into a collection of buckets and the sink to collect the rinse water, then fill the machine with it for the second load. The water from the second load goes onto the garden.
posted by jacalata at 12:54 AM on January 9, 2008 [1 favorite]

I spent a summer at Earthaven Ecovillage, in North Carolina. If you're really interested in all this, you might want to go check them out. They had a small rainwater barrel that was used for washing hands, when I was there, about eight years ago, but they were building much bigger stuff at the time. They also had a greywater treatment wetlands that cleaned the kitchen waste.

When I spent a few months in a developing country, everyone there had rainwater barrels that the roof rain gutters funneled into. You used the water for showering and for flushing the toilets. (You dipped a bucket in and then either poured the bucket over your head for a shower or poured it into the toilet to make it flush.)

Local laws and codes are a huge issue. In San Francisco, they just changed the codes to allow stormwater to be used for things like toilet flushing (so I was told).

So, you rent. Do you have your own washing machine? I've been told that the easiest change to make is to run your clothes washing machine water out onto plants.
posted by salvia at 1:01 AM on January 9, 2008

Response by poster: re: my goals ^

At first, I would like to do simple things like diverting rainwater from the roof and supplementing the tank of a toilet from a collection source. Water for a garden appeals to me. Some areas (in the U.S., at least) "require" that greywater sources be irrigated from beneath the soil and collected supplies be treated somehow. Health issues with using rainwater or greywater on edible gardens concern me.

I have small areas near the front and back doors of my apartment where I grew plants and herbs, took advantage of the runoff, and kept water from collecting at the foundation.

Non-U.S. or Western viewpoints on recycling water are very welcome.

[Upon preview ^...]
I do have a washing machine. In my rental situation, I haven't a way to move or re-use all of the water from the washer, particularly at this time of year. I will look into collecting the rinse water ^ for a second load of laundry.
posted by bonobo at 1:14 AM on January 9, 2008

Response by poster: Sorry, that should be "Non-U.S. or non-Western viewpoints..."
posted by bonobo at 1:18 AM on January 9, 2008

Best answer: Art Ludwig's two essential words on this topic: mulch basin.

Don't build these.

The best way to reuse greywater, in most places, is to get it into topsoil containing lots of organic material as directly as possible. Do not hold in tanks, do not filter, do not reprocess, do not pump. You will not find a better, cheaper, more environmentally friendly greywater reprocessing facility than a foot of active topsoil - provided of course your greywater has not been rendered poisonous, most likely by excess sodium.

Needing to be careful about sodium and boron buildup sounds like a hassle, and may incline you to seek out fancy reprocessing technology - but the simple fact is that if you're not going to dump your greywater to sewer, but intend to reuse it on your own patch, no feasible amount of reprocessing is going to lower its salts content much anyway. All a home reprocessing setup is going to do is remove suspended particles and assorted organisms. Anything actually dissolved in the input water will still be dissolved in the effluent.

If you absolutely must dump toxic crap down your drains and make it somebody else's problem, install a three-way diverter valve. It's a good idea to do this anyway, since there will certainly be times when your local topsoil already has more water in it than it needs.
posted by flabdablet at 1:25 AM on January 9, 2008 [1 favorite]

It used to be standard practice for washing machines to have something called a "suds miser" that would let the machine suck a trough full of rinse water back into itself for a second wash. Nowadays, not so much.

It's pretty easy to damage soil by dumping too much detergent into it too quickly, so until you get the hang of the large mulch basin thing and cutting your detergent usage back to what's actually required (as opposed to the quantity the manufacturer would rather you used) then it's probably best to limit washing machine greywater re-use to rinse cycle water only.

Unless you're a total soap and shampoo fiend living on high-clay soil, your topsoil should soak up any amount of shower and bath water without complaint. Don't drain it too close to the house if the house is on wooden stumps.
posted by flabdablet at 1:29 AM on January 9, 2008

Response by poster: I appreciate the comments and feedback, all. Thank you, flabdablet, for the three-way valve tip and link about greywater errors. If nothing else, I should be able to install a diverter valve on my future kitchen and bathroom sinks. I believe I use soap (particularly laundry detergent) judiciously, but my frequency/compulsions most likely override that--and the soil in this area contains a great deal of clay. Maintaining a compost pile and mulching with it are among the things that enthuse me most about non-apartment living. I learned much about healthy soil through trial and error. Aeration + elevated beds = happier microbes for those us who live on over-developed land and don't live in oft-flooded plains like the really productive local farm lands.
posted by bonobo at 1:56 AM on January 9, 2008

Try this book: Dam Nation, by the people that did the Guerrilla Greywater Girls Guide to Water zine, it has lots of stuff on greywater, particularly from a DIY angle.
posted by tallus at 2:01 AM on January 9, 2008

Response by poster: Thanks, tallus. I added Dam Nation to my Amazon list. I shall pursue that and related books.
posted by bonobo at 2:12 AM on January 9, 2008

Best answer: We have a bathtub/shower thing, so we shower with the plug in the tub and use a syphon to take the grey-water out the window and down the side of the house onto (currently) zucchini plants. Previous crop was green beans and then tomatoes. We're renting at the moment so that's as ambitious as we've got.

I thoroughly recommend the Bill Mollison permaculture books - he deals with grey-water, water-recycling, the joys of mulch and a lot of other stuff you might find interesting.
posted by ninazer0 at 2:26 AM on January 9, 2008

Best answer: I run our laundry water directly on to our non-food garden but I always make sure to use non-phosphorous washing detergent. We have a rainwater tank and use that (via a pump) for all outdoor water requirements. When it's really dry, I save the shower water at the start (while we wait for the water to warm up), and the kitchen water from peeling, washing or cooking vegetables, and pour them on our vege garden.

According to our local authorities, there's a health issue with using laundry/bathroom water on vege patches, so we're not allowed to do that.
posted by b33j at 2:52 AM on January 9, 2008

Health issues with using rainwater [...] on edible gardens concern me.

You what?
posted by atrazine at 3:26 AM on January 9, 2008

We are looking into diverting rainwater from our roof for our non-edible landscaping needs. According to my numbers, we should be able to capture about 51k gallons a year and meet about 30% of our watering needs (woohoo!). Because the water will be coming off of asphalt shingles (which (can?) contain lead), we'll probably need to distribute the water beneath the soil rather than in the current sprinkler set-up. For the vegetable garden we are setting up rain barrels to use capture water for later use. We (ok, I) also try to capture water from the tap that would otherwise go down the drain, and use it on indoor plants, for washing hands, or for drinking water for later. We also use hot-water bottles in the winter to pre-heat our beds, and I reuse that for indoor plants, too. I'm also interested in reading other responses here and will check out some of the books.
posted by cocoagirl at 4:01 AM on January 9, 2008

i have family in the caribbean, and many islands down there rely on rainwater as there is little or no freshwater on the islands (and desalinization can be too expensive). they use greywater inside the house and even blackwater on the yards (which is probably illegal here, due to health codes). i don't have any resources at hand, but it may help you direct your search.
posted by thinkingwoman at 4:29 AM on January 9, 2008

Response by poster: atrazine: When referring to rainwater in this topic, I mean water falling from the sky that is intentionally collected or redirected. (I'm concerned about gutter water, too. As cocoagirl brought up, roofing/housing materials potentially contaminate water.)

Side note: My region is typically humid with an abundance of rainfall. We experienced a (relative) drought with water table depletion during the summer. Yesterday, we had 67ยบ F highs with tornado warnings in an area that tends to be in the 20's this time of year.

Thank you ninazer0 and b33j for sharing your experiences, too.
posted by bonobo at 4:44 AM on January 9, 2008

Response by poster: Thanks, thinkingwoman--some folks in the U.S. call it "dark" grey water. (Doesn't that sound better?) How do your family members re-use water at home and on the yards?
posted by bonobo at 4:53 AM on January 9, 2008

Best answer: We have one small item, a toilet lid sink. As the water fills the tank, it comes out the top so we can wash our hands. Then the water we washed our hands in is used to flush the next time.
posted by L. Fitzgerald Sjoberg at 5:23 AM on January 9, 2008 [1 favorite]

there's a health issue with using laundry/bathroom water on vege patches,

Probably mostly a concern about people washing diapers, and small children doing things like crapping in the bathtub. It's fecal contamination that's the big no-no; avoid that and you are likely to be ok -- too much detergent or household chemicals might kill your garden, but you personally aren't at much risk other than embarrassment.

My real suggestion here is that you should be very careful about unintended consequences. That is, when setting up rainwater catchment and greywater reuse systems, you need to avoid creating new problems while you "solve" the old problem. The most common example I see is uncovered/unscreened rainwater barrels, which are of course prime breeding sites for mosquitoes. Particularly as mosquito-borne diseases are beginning to spread in the US, don't be careless in this way. Other examples include sloppy greywater systems that mix in too much black water without good mitigation steps; inadequate drainage so all the greywater runs off onto the neighbor's yard; goofy DIY plumbing that connects clean water directly to grey/black water, allowing cross-contamination; composting toilets that don't actually compost the waste; etc.

Follow best practices that are appropriate for your climate, think things through, and proceed with care, and it should work out great. Books and websites are ok, but a lot of the claims for how these sorts of DIY ecological projects can be pretty inflated -- the claims are often best-case, plus some optimism, plus the line drawings leave out the three mistakes over to the side. Even better is to visit some already-built examples; if you can find some that aren't really 100% successes, so much the better, so you can see what went wrong. When you do visit, try and get a sense of a) how much specialized knowledge was needed, b) how much this might cost if you did it, c) how much of a pain in the ass is using the thing for the owner and for casual visitors, and d) what the regulatory hassles might be (a topic that the above-linked guerrilla grey water people get into).
posted by Forktine at 5:46 AM on January 9, 2008

Best answer: Here's a pretty do-able thing that me and my wife do (do to our pretty dire water crisis in Atlanta... hey, it's not a lot but it makes us feel a bit better): Put a bucket in the tub while you're waiting for the shower to heat up... tick... tick... tick. Then when it's time for laundry, dump the bucket into the washing machine. Note: our washing machine doesn't "close" the basin until the machine is on. So we have to leave the bucket in the laundry room for a day or so (can't just dump it directly and wait for the clothes to get piled on top.

Saves us about 2 gallons of water each time we wash clothes. Our shower takes forever (more than 60 seconds) to get hot.
posted by zpousman at 5:51 AM on January 9, 2008

Call it gray water, "Dark water" might confuse people with "black water", which is sewage. There are a lot of simple things you can do pretty easily, like toilets with sinks above the tank. Wash your hands with the water, it goes into the tank to be used again.

Rainwater catchment is very easy, and often depending on the placement of the barrel you can actually generate enough pressure that you don't need a pump to push it through a hose. Don't call that graywater though, it's not really.

There are lots of systems you can use too. Ideally, you're using a phosphate free detergent, which means you can catch your rinse water from your dishwasher/clothes washer and empty it outside for whatever purpose, whether non-edible plants or simply watering your grass to return the water to the local watershed.

There are a lot of great resources out there. Check out,, LEED specifications for residential houses, green advantage...there are more, but those are the ones we use often here.

Be advised that in Kentucky (hi neighbor) your laws are probably archaic and it's quite likely that it's illegal for you reroute water either from the storm drain system and/or to reroute graywater to the outside. Welcome to progress!
posted by TomMelee at 6:14 AM on January 9, 2008

This Q&A provides some info on greywater, including links to this book and its corresponding website.
posted by bassjump at 6:23 AM on January 9, 2008

Best answer: We collect the discharge from our washing machine, which drains into a large laundry sink, and run it out to the back yard. We only do this during the summer, when it basically never rains in our Mediterranean climate, and let the rain take care of the yard during the winter wet season. This seems adequate to avoid buildup in the soil of salts, detergents and whatever else is in the laundry discharge.

We drilled a hole in the bottom of the sink and fitted a garden hose to it . Then we drilled a hole through the wall and ran the hose out this hole and down to the yard. The washing machine is on the second floor so when the sink fills up there's enough head pressure to drain the water down to the yard. I keep an eye on it, though, since overflows are a small but real possibility. (A toilet plunger is the tool of choice for starting the flow manually.)

When we want to drain graywater to the garden we put a plug in the normal drain hole. When we want the sink to drain normally to the sewer, we remove the plug and don't worry about the hose - the water would much rather go down the normal drain (although we put a valve in the hole so we can close it off completely if we want to).

Holes are caulked and sealed as necessary. Obviously, we own the place or we wouldn't be making holes in the walls, and I have no idea what the local codes would say about any of this, but it seems to work OK. We don't have much of a garden but we have a few trees in the back and they seem to be doing fine with this system. Good for you for thinking about this kind of thing!
posted by Quietgal at 7:38 AM on January 9, 2008

Best answer: I run my water into a bucket/bin while it's heating up for showers and use it to flush the toilet or water my veggie garden. I turn off the water (or turn it to lower-flow) while soap up. I also collect the water that I use to wash and rinse dishes and pour it on the garden. I don't have gutters on the house I'm renting or I'd lobby for getting rain barrels. My municipality has something like 39ish days of good water left, and things are getting creepily dire. I also conserve using the "if it's yellow, let it mellow" concept.
posted by Stewriffic at 8:18 AM on January 9, 2008

Best answer: Oh, and using the graywater I reclaim from washing up dishes and running water for a shower out on the garden or for my toilets is actually a violation of state law. At a town hall meeting about my city's drought situation last night, however, the Deputy City Manager said nobody from the city government was going to give citations for using reclaimed water. That went over quite well with the attendees, I hear.
posted by Stewriffic at 8:32 AM on January 9, 2008

Best answer: I don't believe anyone has mentioned reclaiming the heat in greywater before it goes down the drain, and using it to preheat water for your water heater, using a heat exchanger. Google "greywater heat recovery". You can recover half, or more, of the heat left in the water, which sometimes goes down the drain pretty hot. So you stretch your water heating dollars by 50% or so, without mucking around with buckets and stuff. It doesn't save any water, however, and I haven't tried it.

I stayed in a cabin once that had an underground tank collecting all greywater, which was then pulled with a hand pump to fill up the indoor toilet tank. The problem was, even though it was just dishwater from the kitchen sink, it got pretty stinky down in that tank and made toilet-going rather unpleasant.
posted by beagle at 9:17 AM on January 9, 2008

I stayed in a cabin once that had an underground tank collecting all greywater, which was then pulled with a hand pump to fill up the indoor toilet tank. The problem was, even though it was just dishwater from the kitchen sink, it got pretty stinky down in that tank and made toilet-going rather unpleasant.

That's a great example of creating unanticipated problems. To make this work (without the bad smells; for any dogs who might want to drink out of the toilet bowl it would be either awful or like the best yummy toilet soup they have ever been given), you would need to filter and/or treat that greywater, and unless you are living in a truly water-scarce situation, it's just not worth it. (And even then, you are better off putting in something like a composting toilet, and just bypassing the need for toilet flushing entirely and using that greywater for something useful.)

Similarly, if you use rainwater for your toilet tank, and you don't screen your rain water barrels to keep out mosquitoes, the mozzie larvae will hatch in your toilet and fill your house. Standard flush toilets are designed with the assumption of having clean water filling them; if you were to design a toilet from the ground up to use contaminated water (like in the cabin example) you would design the toilet rather differently. There is a lot that is stupid and wasteful about how we use water in the US and Europe, but all of the pieces are interdependent, and changing one can affect the others. I'm a big fan of greywater reuse, but be sensible about it -- don't recreate public health nuisances that have taken 200 years to eradicate, don't flood your living room, and stay under the radar of the local authorities.

And again, make sure you are looking at options that are appropriate to your climate. A lot of write-ups of this stuff come from work in tropical places, where you can rely on the disinfecting power of the sun all year round for odor and moisture control. As you move north, pipes freeze, soil absorption changes, the growing season shrinks, the amounts and types of waste going down sink pipes change, and so on.
posted by Forktine at 9:43 AM on January 9, 2008

Best answer: I have a friend who besides using her grey water for her garden, also uses it to soak diapers in. She uses cloth diapers - which I guess you have to soak before washing - and so she keeps a bucket of grey water handy and the diapers go right in. At least that is the way I understand it.
posted by molasses at 10:41 AM on January 9, 2008

Best answer: Re: too much detergent when watering plants
I can't speak to smaller plants, but because of the drought in Atlanta I know a couple people who watered the younger trees in their yard throughout the summer and fall exclusively with laundry water with no ill effect. They use the no-phosphate laundry detergent.
posted by solotoro at 12:45 PM on January 9, 2008

Best answer: I have one of these. It confuses people at first, but if you think about it, your toilet tank and bowl are refilled with clean water after every flush. Doesn't it make sense to use that clean water for something first?

What this does is route the clean water heading for the toilet bowl through a little sink first.

You use the toilet, flush, wash your hands in the clean water, which then goes down into the bowl (not the tank) to be used for the next flush. It is most certainly grey in both senses of the word. Nice little innovation!
posted by scarabic at 12:49 PM on January 9, 2008

Best answer: Phosphate in laundry detergent really shouldn't be a problem for greywater going into healthy topsoil; it's an excellent fertilizer. That, of course, is why phosphate in water that finds its way into waterways is a Bad Thing - it fertilizes algal blooms. Topsoil binds phosphate very effectively until plants growing in that soil take it up.

The main laundry detergent components that kill topsoil are sodium and boron. There is typically more sodium in powder detergents, which often use sodium silicate as a flowing agent, than in liquids. Water softeners also contain lots of sodium as sodium carbonate. Boron is often present as boracic acid (borax).

I know some people who were absolutely scrupulous about choosing low-phosphate laundry detergent, and made up for the reduced performance of their chosen detergent by dumping half a cup of baking soda (sodium bicarbonate) in every load. Their greywater re-use project killed their veggie garden pretty effectively.

These people make detergents designed for safe addition to topsoil. Note that their automatic dishwasher detergent contains sodium; avoid putting that in your garden unless it gets regular flushing from salt-free sources as well.
posted by flabdablet at 2:09 PM on January 9, 2008

Response by poster: Thank you all for your time and input--you've given me much to think about with reclaiming water. Of course, the steps I ultimately take will depend upon where I move. I've really enjoyed reading your accounts and experiences. I will follow up on the links and book suggestions, as well.

Of course, more stories and ideas are welcome! I shall return to mark best answers later.
posted by bonobo at 4:59 PM on January 9, 2008

NPR ran a short piece on "harvesting rainwater" this morning. In addition to the story, they've got photos, diagrams, an excerpt of the book being profiled*, and link to the author's site.

* my Amazon link isn't to the same edition that the story mentions; Amazon has two volumes, whereas the author's site mentions a series of three.
posted by metabrilliant at 8:08 AM on January 10, 2008

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