Monday, July 23, 2012

Simple Ways to Collect and Reuse Graywater

In the last month we’ve traveled to the Pennsylvania - New Jersey region twice, for two weddings two weekends apart. As a result we’ve had a good look at the Corn Belt farmland along I-70 through Illinois, Indiana, and Ohio. It’s a scary sight, even from a car at 65 to 70 miles per hour. Much to most of the corn crop is too dry to give a decent yield, after weeks of above normal temperatures and below normal rainfall coupled with lack of irrigation equipment due to generally adequate rainfall during the growing season. Years like this one, with a drought across the entire Corn Belt, are few and far between. But when we get one, everyone will pay for it sooner or later, in the form of more failed farms and fewer people continuing to farm, and eventually, higher prices for everyone at the grocery store and likely at the fuel pump as well.

At Living Low Farm, the informal name I’ve adopted for our property, we’re also dealing with the effects of weeks of heat and drought. The drought started later in the St. Louis region than in much of the Corn Belt due to more than sufficient rain through the end of April (I measured 9.2 inches of rain at our property in April!). Once May began, conditions turned dry. Our May rainfall total was about 1.4 inches, the June total about 1.6 inches; so far in July I’ve measured only 0.2 inches of rain, though some locations in the metro area have gotten more from scattered thunderstorms. It was around the summer solstice that drought conditions at home first caught my attention in the form of dormant grass and groundcovers, drooping plants in the rain garden, and leaves curling or drying up on some shrubs. Not long after that I started rescue irrigation on other areas of the farm besides the vegetable garden, usually the only place that I irrigate and then only during (usually) temporary dry periods. I do most of the irrigation by hose and sprinkler. We are fortunate that St. Louis County gets its water supply from the Missouri and Meramec Rivers and can share water with St. Louis City which draws from the Mississippi and Missouri Rivers, so I have access to all the water I can spray out and pay for, at least for the time being. I’ve also used all the water our rain barrels have collected, but they go dry before the next rain in a drought like this. Below I’ll discuss how I have put reused water, called graywater, to use since I first noticed the need for it. Since the methods I use are low cost and do not require any changes to your plumbing, some of you may find them of interest. Please remember that everything I write below is for informational purposes only; I cannot and will not be held responsible for anything you might try that causes water damage or other problems. I will do my best to point out pitfalls and cautions, but I am not advocating that you do anything, just sharing some thoughts on what we’ve done and how it has worked.

Graywater is water already used once for some purpose that has no or minimal bacterial contamination and hence could be captured and re-used for irrigating some kinds of plants. The water from your toilet is considered to be blackwater due to its high bacterial levels, so it cannot be reused and must be sent to a sewage plant for processing. Water from your sinks, washing machine, and tub or shower is called graywater. It has small amounts of bacteria, skin cells and secretions, soap or detergent, soil, contaminants such as grease or oils, and/or small food particles in it. You can’t drink such water, and you can’t pour it directly onto plants whose leaves, roots, fruits, or seeds will be wetted by that water because they will become contaminated. Don’t irrigate your vegetable or herb garden or your strawberry patch with graywater! However, graywater can be put to beneficial use to irrigate ornamental plantings, shrubs, or trees, including fruit and nut bearing species whose fruits or nuts are high enough that they won’t be contaminated by splashing water, as long as the plants can withstand whatever contaminants are present in the graywater.  Irrigating trees, shrubs, or woody vines planted within the past year or two with graywater puts my time and labor to haul the water from source to plant to the best use, as these are valuable plants with small root systems and thus at greatest risk in a drought. I irrigate those planted in the previous spring or fall first, then those that have spent at least a year but less than two years in place.

Two important points about using graywater come courtesy of Peter Bane’s new book The Permaculture Handbook: Garden Farming for Town and Country. The first is that graywater must not be stored longer than 12 hours between its generation and use on the landscape, since the bacterial population will grow over time until the water is absorbed into the ground. The second is that graywater can’t be poured onto soil that has enough moisture that the graywater won’t sink in very soon after it is poured on the surface, in order to avoid contaminants getting into surface water. The graywater needs to be absorbed rapidly into the soil so the soil microbes can decontaminate it. In areas which receive little rain during the growing system, it can be useful to put time and money into systems that pump out and distribute graywater from all household sources throughout a landscape. In places like St. Louis where rainfall is generally adequate and sometimes excessive during the growing season, I think it makes more sense to put together makeshift, low cost systems for the occasional capture and reuse of graywater when needed to mitigate a drought.

The easiest graywater to collect and use is water left over after washing and rinsing dishes. I use a plastic tube as a siphon and a 3 to 5 gallon bucket to collect the water. Plastic tubing can be obtained from a pet store that carries aquarium supplies, a retailer that sells pond supplies, or a home brew or wine making supplier. I use a 4.5 foot long plastic tube, long enough to reach from the bottom of our 6 inch deep kitchen sinks to the bottom of a bucket on the floor. If I had a shorter tube, I would put the bucket on a stool or chair low enough so the bottom of the bucket was below the bottom of the sink. I collect and use the rinse water separately from the wash water since I have a double bowl sink. I fill the siphon tube by submerging it in the sink, blocking both ends with my thumbs, then leaving one hand with the blocked end in the sink and moving the other hand with the blocked end into the bucket. Once the end of the tube is well into the bucket, I unblock both ends and the water flows into the bucket. I could fill the siphon tube from the faucet, block both ends, and proceed as before. If the wash water has a lot of grease or oil on it such as after washing the dishes from a highly fatty meal, I don’t use it since I am not sure if the soil microbes can handle that much grease, instead sending it down the drain as usual.

I could collect and use the water from a bathroom sink in the same way. So far I haven’t because we have water-conserving habits, thus it would take some hours to collect enough water in the sink to siphon out; meanwhile bacteria would multiply in the standing water. But if I filled the sink for washing tasks, it would be worthwhile to siphon out and use this water for irrigation as well.

I could collect a considerable amount of water from our bathtub for use in our landscape, but since the tub bottom is close to the floor, gravity is not much of a help in getting the water from tub to bucket. A cheap hand pump that doesn’t choke on hair would transfer the water from tub to bucket more effectively. I haven’t looked for one yet, but I might do so.

Washing machines use a lot of water that could be diverted to the landscape but present difficulties in accessing it as most washers pump the used water directly into the household drain system.  However, if the washer drains into a utility sink and the sink can be plugged, one could proceed as in the case of dishwater, as long as the sink is large enough to hold all the water from the machine. I would want to know both the sink capacity and the total amount of water from wash, rinse, and spin cycles and verify that the sink can hold that much water before trying this. Splashing onto the surroundings when more water forcefully enters a partially-filled sink is a potential issue. This isn’t something I would do in a finished utility or laundry room or anywhere that doesn’t have a concrete floor because of the risk of water splashing where it shouldn’t.

Our washer’s drain hose fits into a larger pipe leading to a floor drain in our unfinished basement. We have an old metal washtub we acquired at a garage sale. After some messy experimentation, I determined that I could pull the washer drain hose out of the pipe and pass the hose through a 3 inch C clamp that I clamped tightly to the side of the washtub, with the outlet of the hose directed downward into the washtub. (Note: an unclamped hose moves around as a result of the force of the water being pumped through it, spewing water in various directions. It’s a good thing our basement is unfinished and has a concrete floor.)

I was unable to find a plug to fit tightly in the washtub drain, but a description and photo of the new washtubs in the Lehman’s catalog reminded me that if I could attach the outlet end of the washtub drain hose to the top of the washtub, the water would not drain out of the hose until I moved the outlet end below the top of the water level. While the washtub drain hose was a little too short to reach to the top of the washtub, it came close enough to the top that I could improvise a hose clamp from a rubber band wound over the end of the hose and stretched over the upturned end of a curtain hook that I draped over the top edge of the washtub (I could have made a similar hook out of a large paper clip). In this way I can capture most of the water used by our front-loading, water conserving washer for reuse on thirsty plants. A wet floor a couple feet or so surrounding the washtub lets me know that not all the water makes it into the tub, something that isn’t a problem for us because of the concrete floor and lack of furnishings in that area. After the washer finishes, I dip a bucket into the collected water or unhook the washtub drain hose and direct the water into a bucket, re-hooking the hose in place once the bucket is full and until the washtub is emptied.

If we hadn’t already had a washtub, we might have considered the purchase of a plastic free-standing utility sink and collected the water in it similarly. Some general hardware stores carry these sinks. One issue might be whether or not it is sturdy enough for this application. Lehman’s carries new metal and plastic washtubs at corresponding prices, but it may be possible to find an old one at a garage or estate sale at a much cheaper price, as we did.

I also did laundry directly in the washtub, using my own power, reusing the wash and rinse water to irrigate plants. I’ll describe that in a separate post, but it could be a few weeks before I get around to writing it. This blog is supposed to be a rainy day and winter project, but it isn’t raining and it’s a long time till winter, hence it might be awhile till the next post.


  1. another washer/laundrytub trick is to place a bucket in the laundry tub and hook the outlet hose from the washer into the bucket. place in a way that if the bucket runs over, as it likely will, the water overflowing the bucket can go on down the drain, saving you the cleanup of an overflow if you are busy elsewhere at the crucial moment.

  2. I am considering setting up a greywater system integral in the plumbing, but I think it would be against code. My understanding is that the code in use in St. Louis City and County requires the use of a small 55 gallon cistern along the outflow, which seems very silly to me as it would only increase bacterial issues. According to Oasis Design, a greywater company, there are 8 million unpermitted greywater set-ups in the US; not that I'm advocating being the next one, of course

    1. I think the cistern is there to hold the water temporarily and allow it to be fed out more slowly through the landscape than it would be if, for instance, it came straight out of a clothes washer. Feeding the water more slowly would probably allow it to soak in more thoroughly rather than possibly puddle up on the surface. At least that's what I remember from reading graywater articles and books awhile back. I'd rather not take on the expense and code hassles of an integral set-up, especially since we have more than sufficient rainfall at times to saturate the soil. One of those times could be this coming weekend if we get enough rain from Isaac's remnants.