Many people often wonder what grey water is exactly, and simply put, it’s all that water that drains out from your washing machine, showers, bathtubs, and more—any used water that does not contain human waste. Grey water is an important part of sustainable living because it is easy to treat and reuse in your home for several things. There are a number of countries that are already using this method, but for a majority of the US, this process isn’t heard of. Water is used and then simply discarded. However, one of the best places to start to help the drought in your area is to consider using grey water, and luckily, it is becoming a more and more common thing.
While recycling grey water is not difficult, it still requires a bit of care. You have to remember that grey water likely contains traces of soap, bacteria, chemicals, and pathogens. This poses potential, although somewhat exaggerated, health risks from irrigating edible crops with grey water, for instance. The second thing to consider is the system you use to collect and utilize the water. Overly elaborate or completely inadequate systems will cost you more in the long run – both in money and energy efficiency. Another thing to consider is that you will most likely need a permit before even attempting to install one. However, that is not to say that you cannot or should not take up a grey water project. In fact, there are practically zero downsides to recycling grey water, as long as you go about it the right way.
So now that you know there will be challenges, here is a handy guide to navigate the pitfalls you may face along with a few ideas for recycling your grey water.
First let’s start off with some common mistakes that are often made when reusing grey water. Although there have been zero reports of illnesses caused by grey water recycling, it does not mean that we should not exercise care when implementing grey water systems, especially when those systems are home projects with little or no filtration involved. Avoid using pumps and complicated filtering systems as much as possible. These require a lot of maintenance and cleaning, not to mention the unnecessary drain on electricity. A system that allows grey water to naturally flow downwards is much more efficient. However, take care to ensure that grey water is not allowed to pool inside the system. The better the water flow, the less chance bacteria and other microorganisms have to proliferate. If someone in your home has an infectious illness, avoid using grey water until the infection has passed. There is no big mystery as to why; it just makes sense to avoid introducing viruses and bacteria into your recycled grey water. Never allow grey water to be mixed into animal feed or drinking water—that includes using grey water in close proximity to water and food sources, where accidental cross contamination can occur. Also remember that the quality of your grey water is completely dependent on what goes into it, so use only natural soaps, shampoos, and washing detergent for the purest results.
However you implement your system, you must take into account that you cannot store grey water for longer than twenty-four hours. So again, keep in mind that the system should allow you to reuse water as quickly as possible. Obviously this also provides the added benefit of reducing the build up of scum, pathogens, and bacteria.
Watering Plants and Crops
Grey water is alkaline, so you should never use it to water plants that thrive in acidic soil. You can use grey water to irrigate other plants, as well as crops and trees. However, when using water that is untreated, apply it directly to the soil, and do not use grey water on edible root vegetables. The easiest methods of applying grey water in this way include underground irrigation systems; a grey water diverter valve, which allows you to send the water to a storage vessel; or, a siphon primer pump that can draw grey water directly from a bath into a hose. More expensive systems are available with advanced filtering; however, you have to consider that these types of systems require maintenance and upkeep. Installing any of these systems requires a varying degree of skill and labor. An underground irrigation system is obviously the most difficult and costly to install. For new builds, however, this should be your first consideration. The diverter valve is a much easier option for current homes, as you simply connect an equal tees splitter to the bathroom wastepipe before the sewage entry point. This allows you to divert your grey water into storage in a way that works best for you. If you are treating sloping gardens or crops, for instance, you can allow the water to run directly into the soil. You can also use a siphon filter in one of two ways – by draining the water into storage or by direct application using the connected hose.
There are a few schools of thought on using grey water in toilets, as a number of problems can arise. These include bad smells, staining, water backing up into drinking supplies, and fouling of water tanks. However, when the water is pumped directly into the bowl rather than through the tank, using grey water to flush your toilet is perhaps one of the most efficient recycling methods. The important thing to remember here is that there are varying degrees of grey water. For instance, bath and washer water is further towards the black water scale, whereas water flowing continuously from a shower or sink is significantly cleaner. In the case of the latter, installing valves and a storage tank will allow you to direct free flowing grey water straight from the source and into the toilet bowl. For this system to work, the source of the grey water must be higher than the toilet. For instance, an upstairs shower or sink feeding into a downstairs toilet would be ideal. To ensure that the grey water is used in the most efficient way possible, you will also need to incorporate an overflow into the design. If you are feeling up to the challenge, you can even divert the overflow to your grey water storage for irrigation. For really busy households where the bathroom sees a lot of traffic, another option is to install an outlet valve that runs into a bucket. The resulting grey water can be poured directly into the toilet bowl, as long as you are confident that it will be used fairly quickly. The great thing about this type of valve is that you can open and close it as needed. Alternatively, you can install a more advanced system that will store grey water for flushing the toilet; however, these types of systems tend to be expensive.
Washing the Car
Remember, not all grey water is the same. If you decide to install the outlet valve discussed earlier in the article, the collected water is perfectly acceptable for washing your car. To further purify the water, you can mix it with rain or fresh water, and boil it to help kill off pathogens and bacteria. A good idea is to wash the car with your grey water and then rinse with fresh water. Or, if you are expecting rainfall, let nature do the rinsing for you. This method is also great for washing garden ornaments and shed or barn windows.
Throughout this article I have alluded to the fact that the more advanced grey water recycling systems are expensive. I must stress though, that the cost is subjective, depending on the circumstances. If you are implementing a grey water system in your home, the amount of plumbing and rerouting required would be more costly than the simple systems discussed in this article. The same is not necessarily true for new builds, however. Another point that I touched on is how well the system is designed and integrated into the building. Basically, there is no such thing as one size fits all when it comes to grey water systems. Distance and the lay of the land are two important factors to take into account. First of all, consider where the water is coming from. Then you need to figure out the quickest, cleanest, and most efficient way to get it to where you need it. Another factor involved is frequency of use. There is no point installing a system that relies heavily on storage if the water is allowed to stagnate. Remember, what works for your neighbor may not work for you.