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Greywater: What Is It and How Can It Make a Difference in Your Home?

Posted on February 1, 2017 by Rachel Tardif There have been 0 comments

What Is Greywater?

Thousands of gallons of water go down the drains in your home every year, but not all of that wasted water is the same. Around a third of home wastewater is flushed down the toilet or run through a garbage disposal. This water, known as blackwater, is contaminated with fecal and organic matter and requires filtration and chemical treatment before it can be returned to the environment or reused. The other two-thirds of household wastewater is much less polluted. Water that enters the sewer systems through bathroom sinks, showers, dishwashers, and washing machines – termed greywater – has much lower pollution levels, and so requires less treatment to be reusable. Because greywater accounts for such a large amount of household water waste, its retention and reuse has become a major focus of efforts to conserve water and reduce the amount of energy and chemicals that go toward sewage treatment.

The main difference between greywater and blackwater is the presence of fecal and organic matter that can carry or promote disease. While urine is usually sterile, there are numerous dangerous bacteria and pathogens that thrive in human fecal waste. Blackwater also has a very high nitrogen content, which can be extremely dangerous to natural ecosystems. For these reasons, blackwater needs to be treated and filtered at sewage processing facilities before it can be safely released back into the environment (it is possible but rare for sewage treatment facilities to produce potable water that re-enters the drinking supply).

Greywater, however, contains a much lower level of contaminants. It is free of fecal matter and contains lower concentrations of nitrogen and phosphorus, which makes it easier and safer to capture for reuse. It’s important to keep in mind, though, that while greywater is cleaner than blackwater, it is not potable without filtration and treatment. Instead, most greywater recycling technologies will funnel captured water into irrigation or toilet flushing. In addition, untreated greywater cannot be stored for more than 24 hours before it is overrun with bacterial infection.

How Can You Use Greywater at Home?

In a typical house, greywater and blackwater are combined before being sent to sewage treatment facilities, even though greywater does not require the same level of purification, so the first step in greywater recycling is to ensure the two remain separate. Many new building projects, especially those touting themselves as eco-friendly, will include separate wastewater removal systems so that greywater can be reused. If you’re looking to install this type of plumbing in your home, be sure to consult a professional in your area: most cities have regulations about greywater reuse, and often there will be specific types of piping required for recapturing greywater.

Once your home is outfitted with separate plumbing systems, it’s possible to install a range of greywater systems. The simplest greywater recapture systems are tanks with filters that will pump water back into your toilet or into holding tanks to be used for irrigation; in fact, the nitrogen and phosphorus levels in captured greywater make it ideal for watering and fertilizing your lawn. It’s also possible to install more complicated systems that will filter the used water more thoroughly so it can be used for household chores like washing dishes and doing laundry. In general, irrigation and other large greywater recapture systems will need to be professionally installed, as they involve separate plumbing for grey- and blackwater as well as filters and storage devices that will vary depending on the amount of water being captured and its intended end use. And again, you’ll want to make sure any system you have installed is legal and fits your local building codes.

Even if your home is not specially built for wastewater recycling, you can still install systems that will allow you to recycle greywater. The easiest place to capture and reuse greywater is in the bathroom. Kits are available that allow you to catch and filter water from the sink to be used in the toilet—this system can reduce home water usage by up to 20 gallons a day. And, of course, if you want to recapture greywater without all the fuss, you can just stick a bucket in your sink to catch rinse water while you're doing the dishes or washing your hands, then use that water for cleaning or watering plants.

If you start recapturing greywater, you’ll want to make a few changes to keep your system running well. Be sure to use non-toxic soaps made from cleansers likes citrus, soy, or enzymes that naturally biodegrade—this will decrease the level of harmful chemicals in the water and minimize the work your filters have to do. Also make sure you use water in the your home efficiently so you don’t overwhelm your new system.

The Bottom Line

Whether it’s a do-it-yourself kit or a major home renovation, installing a greywater recycling system in your house is a great way to reduce water and energy usage. Not only will your own utility bills decrease, but you will also lessen your impact on the environment by reducing the amount of water you draw from natural sources and by lowering the volume of contaminated water handled at sewage treatment facilities.

This post was posted in Blog and Green Library, Defining Green, Eco Home Improvement, Reduce, Reuse, Recycle, The Water We Drink, Your Green Home and was tagged with CONSERVES WATER, Eco Home Improvement, ENERGY EFFICIENT, Green Your Home, SUSTAINABLE, water conservation


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