Water Conservation

Using Gray Water When It’s Too Late to Design Your Home for It

Recently, I wrote an article about passively heating and cooling homes when they haven’t been designed well for it, and to my delight, lots of people left comments, many of them appreciative, regarding the tips. Within those post-article conferring, someone asked for a similar article in relation to gray water usage, so here I sit with that task at hand.

Before delving too deeply into it, I just want to say that I believe these sorts of intermediary steps from conventional living to a more sustainable and self-reliant lifestyle are perhaps some of the most important we can address. The sad fact is that most homes haven’t been designed optimally for energy-efficiency and resource management, which means that many people—existing homeowners—don’t realistically have the option to acquire or build a “permaculture” home from the ground up. Retrofitting might not even be possible right away. They’ve already got a place and just want to make the most of that situation. It’s important, in the name of progress, to meet them along those lines.

Water conservation is a huge part of what we have to do as permaculturists, and in ideal conditions, our homes are designed to deal with day-to-day gray water rather mindlessly. Sinks and showers drain into reed beds and cycle back into the eco-system. Modern conveniences like washing machines and dishwashers are hooked up to immediately feed into filtering systems. Unfortunately, for those who don’t have these ideal systems, dealing with gray water is a little more labor-intensive. However, there are some options available for those who want to work within the confines of a home not designed to deal with gray water.

Technical Difficulties (Courtesy of Keith)

How the Water System Works

When plumbing isn’t set up to carry wastewater to its appropriate onsite spot for filtering and/or reintroduction to the immediate environment, perfectly usable gray water is usually combined with black water, creating a much larger amount of heavily contaminated slush that must be treated. In some cases, especially in more rural locations, this happens in septic tanks that have leach fields for a subterranean reintroducing of the water that cycles through them. In urban environments, gray and black water are more than likely combined and sent to treatment plants, where they are chemically “cleaned”. Neither option is optimal.

Dealing with gray water separately from black water is important because it isn’t necessarily dangerous and, prior to being mixed with black water, doesn’t need the same kind of treatment. Hence, the mixture creates much more contamination in a much larger amount of water than need be. (Check out Humanure Is No Laughing Matter, a two-part article, for some thoughts on minimizing black water.) If gray water is never mixed, it is much easier to use and often can be applied right to garden systems. Combining gray and black water elevates the risk for the environment, animals, and people.

Pipe End (Courtesy of Ben Sutherland)

Catching Gray Water Manually

Regrettably, homes that haven’t been designed to work with an automatic gray-water system are going to require more effort to avoid further contaminating gray water with black. More than likely, it is going to have to be dealt with, at some point, manually. This might mean leaving the tub full while that water is moved to different places. It might mean disconnecting the sink drain so that it drains into a receptacle that can be emptied in a more environmentally friendly location. This is the difficult price of combining bad design with a permaculture mindset.

One thing that can help to make the bulk of household gray water more versatile for secondary use it to avoid chemicals. That means using biodegradable, natural soaps. It means making home cleaning products from safe ingredients. Keeping the water free of harsh and harmful chemicals of makes the resulting gray water much eco-friendlier, which diversifies the ways in which it can be safely used. To put a blunter point on it, cleaning up the household gray water produced is the first step for using gray water when it’s too late to design a home for it. When it’s kept relatively clean, using it becomes much easier.

Kitchen Sink Drain (Courtesy of Hey Paul)

Where to Empty Those Buckets

Hoping that some people don’t find the notion of gray water buckets—collecting beneath the sink, bailing out the bathtub, getting the drain from the washing machine—too far a reach, the next question is where all of that gray water should go. (Note: This is why efficient design is such an important part of permaculture: To avoid having to do this type of stuff.) The good news is that, assuming the water doesn’t have chemicals, there are many places to put it to good use.

For the basic bathwater, bathroom-sink water, or washing-machine water, in which nothing more than soap and a few skin cells are dirtying it, the water can be used in several ways. Firstly, having a couple of buckets of this water to use in the toilet would prevent using perfectly clean water to flush, which is notably worse than using gray water. This relatively clean water can also be used to mop floors, wash cars, scrub sidewalks, clean tools, and do other basic tasks that would normally use up clean water. It can also be worked through compost systems, used directly but cautiously on trees and grasslands, or dumped into mulch pits.

Kitchen water can be a tad different as it can be exquisitely clean or notably greasy. For water that is used to wash vegetables, boil pasta, or something of the like, that water—once cooled—is great for water plants, including potted houseplants. In the case of greasy pots, it’s good practice to use a drain screen to remove any solids, and cleaning these dishes separately is probably the best idea as it would create less greasy water. With regards to the greasy water, a simple, DIY biological grease trap can filter it while providing some greenery.

Sink Tomato in Clogged Drain (Courtesy of Radu Privantu)

Final Thoughts on Gray Water

For those with houses that aren’t set up to responsibly and passively deal with gray water for them, dealing with it can be somewhat of a hassle. Catching water in buckets and dumping them adds extra steps to basic tasks like washing the dishes, doing laundry, or taking a shower. In reality, even under these less than ideal set-ups, these efforts can also become slightly more efficient as certain gray water gets designated to specific tasks based on making the waste cycle efficient and productive.

There are a couple more important things to keep in mind when approaching this makeshift gray water system. The more stuff, such as soap or detergent, that is put into the water, the more difficult it becomes to use. It makes sense to avoid soaps when possible—washing a drink glass—and using alternatives to it, such as soap nuts for doing laundry. Using water conservatively still very much factors in to what’s happening: Just because the gray water has found a new, more ecological route doesn’t mean we should use clean water haphazardly. Creating less gray water is a huge part of the goal here, especially when a bucket needs to be emptied every fifteen-to-twenty liters.

For some, the rudimentary systems presented above are a little too far out of the box. That’s understandable. In that regard, two things should be realized. This need only be a temporary or part-time effort to improve the situation, which is to say start by using pasta water and water used to wash vegetables if that’s all that seems realistic. Expand slowly from there. For those with the money to retrofit, more convenient gray water systems are available and, in many capacities, not all that difficult, either via DIY projects or hired professionals. The point is to do something rather than nothing.

Header Image: Grey Water Garden (Courtesy of Jeremy Levine)

Jonathon Engels

The financially unfortunate combination of travel enthusiast, freelance writer, and vegan gardener, Jonathon Engels whittled and whistled himself into a life that gives him cause to continually scribble about it. He has lived as an expat for over a decade, worked in nearly a dozen countries, and visited dozens of others in the meantime, subjecting the planet to a fiery mix of permaculture, music, and plant-based cooking. More of his work can be found at Jonathon Engels: A Life About.


  1. For specifics on greywater capture and use, I highly recommend checking out Art Ludwig’s website at http://www.oasisdesign.net, through which you can access some articles/tutorials along with links to purchase his excellent books on the subject.

    One thing that homeowners need to be aware of with their construction/retrofits is code compliance. Greywater capture and separation is still illegal in several states in the US or has special conditions. For instance, in NY where I live, environmental rules and regulations stipulate that greywater must undergo chemical treatment before use. Now many of us permies know that this is counterintuitive and counterproductive (not to mention expensive), but if you want to remain above-board you need to take these into consideration.

    For example, we are currently doing a major renovation to our house that includes significant energy efficiency upgrades, and I wanted to plumb out upstairs utility sink for the option to direct greywater outside into a reed bed for treatment. But to install the plumbing necessary to do this as part of the permitted construction would have run afoul of these regulations. So, I’m stuck with having to either do it on the d-l later on — and with some collateral damage to the external aesthetics — or go without greywater diversion. Carting around buckets and such just really isn’t feasible for most of us who already have harried schedules from trying to live with one foot in the current world and one in the permaculture world.

    1. Hi Christopher,
      Perhaps getting the pipes in place first without connecting them during your renovation works and then connect them up later DIY might work? Just a thought…

      1. I actually gave that serious consideration and put it into an initial design for my home renovations, but the problem is the plumbing inspection for the building department. If I have drain lines installed the penetrate through the wall to the outside, it’s kind of a red flag.

  2. There are a bunch of grey water systems which can be retrofitted. One example being the stuff from https://www.greyflow.net.au
    They can get costly tho!
    Not affiliated with awws in anyway that’s just the one that came to mind due to its use in a case study build Josh’s House which I am familiar with
    http ://joshshouse.com.au

  3. We use a tub that fits into our sink to wash the dishes; once a week we use the sink to avoid the drain becoming smelly. The water waters our small patch of lawn.
    We also catch the water from the shower as it heats up. Clean water that waters the pot plants.

  4. Consider me a guinea pig: I may be a good example of someone who is dancing around the fringes of a permaculture lifestyle, attempting where I can to implement its principles, but more in the style of a scientist or hobbyist than a committed practitioner. Still, maybe someone else can find value in one thing I’ve done that I’ve found rewarding, even if only aesthetically.

    Here in Texas, where a conventional lifestyle turns maintaining a heat-and-air system into something more like a survival skill, I’ve put a lot of money into mine. A couple years ago the condensation line became clogged, and rather than pay to repair a problematic pipe that simply dumped the water out through a hole in the wall, I chose to double or even triple the plumber’s bill by turning that into a watering system that reroutes it to a planting bed.

    Granted, this planting bed is exclusively ornamental plants, and my guess is you’d have to add filtration in order to use this water on a vegetable garden. But the point is I’ve reclaimed personal value from waste water, and someone else may apply the same idea to a more essential need. And now that I have it established, I could always upgrade my system later if I wanted to irrigate edible plants.

    Of course doing it wasn’t cheap, but I justified it by weighing the cost of maintaining a wasteful system against something that might give us pleasure and increase the curb appeal of a house we will someday sell. I think it cost something like $1200, compared to around $600 to repair the line.

    The plumber set up a system where the condensation water from the heat-and-air system is collected in a rain barrel and is then pumped out to a soaker hose in the planting bed. Because the furnace is a high-efficiency one, it produces condensation just like the air conditioner does (it’s cold in Dallas this week, so I hear the pump working as I write this). And so the soil and root systems of my plants are both kept moist year round, which means they bounce back immediately when the weather turns warm again. Elephant ears make up most of the plants in the bed, and by the fall they’ve reached 5 or 6 feet in height with leaves that are almost 3-feet long.

    This is of value to me because it adds a low-maintenance (almost NO-maintenance) feature to my home and reclaims value in water that would otherwise get dumped out onto the ground.

  5. I have came across a variety of interesting ways to capture laundry grey water and I have always wondered how areas with freezing temperatures deal with the piping to the outside. Every article seems to imply you live in a nonfreeze zone.

  6. I always run the hot water tap into a bucket until the water becomes hot, instead of letting it run ‘away’ down the drain. Many of my friends now adopt this same idea

  7. We are putting in a substitute drain line from the washing machine to a greywater drain-line which will drain to the swale before the garden. We will switch the drain from whole-house-into-the-septic-tank drain at the laundry to the greywater drain when we are not washing greasy clothes or dirty diapers.
    Also, a drain line “T” will divert one of the bathtubs to a different greywater pond and then swale at the fruit trees. This is also the tub where clothes can be hand washed if worse comes.
    Unfortunately, the other drains are not easily converted, but these two seem to be do-able with very low cost.

  8. Catching the water from the shower heating up is very easy. Then I put that bucket next to the toilet, to flush when little water is needed.

  9. If you are fortunate or intelligent enough to own a medium or high set timber floored house in a warm climate, it is very easy and cheap to divert grey water into your garden.
    A simple neoprene funnel from your nearest plumbing supply or hardware store will do the job. Connect this under the floor to the outlet elbow and run a 3/4″ or larger poly pipe to the downhill swale of your choice.
    I did this from my bath and vanity basin which feeds a large banana circle and grape vine.
    The laundry is even easier with the washing machine outlet connected to another 3/4″ poly pipe and drained to a garden bed below the height of the washing machine pump outlet giving me a good elevated gravity feed.
    The kitchen sink has yet another neoprene funnel inserted into the outlet elbow under the house and it drains into a shallow ditch at the start of another swale. Greases and oil are not a problem if you are sensible about your dietary choices and there is absolutely no need for a messy and possibly mosquito attracting grease trap as oil and grease are very quickly bio-degraded by a range of soil bacteria, worms and miscellaneous small insects to produce nitrogen rich and moist soil.
    I’ve done this for the last 35 years or more at my various farms and residential addresses and have never had any problems other than having a rampant green food forest jungle to manage.

  10. Can someone point me to a permaculture critique of septic tanks? I’d like to understand whether nutrients etc are being “cooked off” etc.

    1. The drainage field below your septic tank has nitrogen rich nutrient on offer so is great for papaws, bananas and other nutrient loving plants. Trouble with septics is that they are basically aerobic decomposition, not generally being well sealed enough for anearobic. This means that all of the Methane, hydrogen, carbon dioxide and all of the other gasses produced, vent into the atmosphere. Ideally you would have a biogas reactor located before the runoff trench, to capture the gas for cooking purposes. I did this using a modified 1 cubic metre IBC plastic tank, modified to capture the gas.
      Works well but sadly it’s not legal here in suburban SE Qld to plumb it into the toilet, so I am obliged to run it as a stand alone system fed with cow manure etc. Great cooking gas and rich liquid manure are the results for me here.
      Hope this helps.

  11. A good middle ground between buckets (seems like way too much work) and plumbing, is to use a hose to siphon bathtubs and sinks. We have our gray water plumbed in now, but before that I used to keep a hose near the bathroom window, and every night I would siphon the kids bathwater out into the landscape. Just use a tap on the outside to create the siphon, then when you disconnect the hose from the tap the water will begin to drain from the tub provided you have a bit of downhill slope. Google will provide a better description of the process.
    I’m not sure how this would work with laundry water, other than draining into a bin of some kind and siphoning from there.

  12. My small contribution to saving water is having a bucket under the sink. First I drop into this all compostable materials such as fruit, vegetable cuttings, egg shells, coffee grounds, lint from dryer, left over coffee, liquids from boiling potatoes, pasta, rinsing out coffee pots, drink glasses etc.
    After a meal, I use the paper napkins to wipe the plates with the help of a little water into this bucket; (drop the napkin into the bucket as well) as the compost pile is always in need of a little moisture…the bucket is emptied at least once a day, depending on the activity in the kitchen.
    The compost piles are active and seemingly happy with this arrangement, as I have a steady supply of beautiful, rich, dark compost to add to my flower beds and potted plants, vegetable as well as ornamental.

  13. I just posted about my compost pale….however, I also have a rain barrel plus place large containers along the drip line to catch rain water run off from roof…they have well fitting lids so as to avoid mosquito breeding….while this water lasts, I use it to water all my flower beds and indoor, outdoor potted plants saving much fresh water from faucets.

  14. I think converting a double bowl sink so one plug hole drains relatively chemically clean water to the garden and the other to send chemically dirty water to sewer or the septic tank would make sense. Most sink uses are clean but is something is oily or chemically dirty or likely to not be good for the garden then use the “dirty” sink. Occasionally send clean water down the dirty sink to help keep it moving and change over the water trap water.

    A plumber should probably be consulted. There is venting, water seals, and end of pipe issues all to be considered that are beyond most people. Try mocking up a model of any proposed system out in the shed to test it first might also be in order.


  15. In my research, I have come across a variety of interesting methods of capturing laundry gray water, and I have always wondered how areas with freezing temperatures handle piping to the outside. You seem to live in a nonfreeze zone in every article.

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