What Is Greywater? Living Greener with Grey

By Maureen Wise in Thinking Sustainably

Learning how to conserve water is an important step in your family's journey toward sustainable living. You probably have already started taking shorter showers, turning off the water while brushing your teeth, fixed any dripping faucets, installed a low-flow shower head or two, and are instilling water conservation habits in the little ones in your life. If you've already checked off all the easier boxes, using greywater in your home is a way to really up your water conservation game.

But what is greywater? Water that goes down the drain from your shower, bathroom sink, or washing machine (unless you're washing cloth diapers) isn't that dirty. It may be a little soapy, but this water is usable for lots of non-drinking purposes. Water from your toilet, kitchen sink, and dishwasher is considered black water (including sewage), and is not able to be reused untreated since it contains too much food and bacteria, defines the Water Wise Group. Greywater, however, can be used twice, which can really cut down on your water consumption.

Using greywater on a large scale requires rearranging your plumbing and may tangle with zoning rules in some communities. But there are quite a few ways you can reuse your greywater without rearranging your entire house.

Collecting Warm-Up

Every day we wait for the water to warm up before a shower, as we rinse dishes, or while we wash our hands. This cool water just goes down the drain, but it can be used directly in your home instead. There's no need to install new pipes to collect this untapped resource, either. Simply keep a bucket—or even a watering can—in your shower or sink to collect this warm-up water and use it to feed your houseplants or flush your toilet.

toilet-top sink


Speaking of toilets, I am excited to share that there are now toilet lid sinks on the market for homeowners. These devices range from just under $100 to about $150, and are such an easy way to recycle water! A small sink fits right on top of your toilet tank lid, and the water going down the "drain" becomes your toilet flush water. They are clean, safe, and compact. With only minimal plumbing adjustments, you're quickly using water that you washed your hands with to flush.

Rainwater Harvesting

Rain running off your roof and down your driveway or sidewalk is considered stormwater, not greywater. It goes into your city's storm sewers and flows downstream into your local lake, river, or reservoir. Although your property's stormwater is not defined as greywater, collecting rain water deserves a nod in the conversation about collecting and repurposing household water. Using stormwater collected in a rain barrel is a great way to water your vegetable garden or flowers in the warmer months. It's also a visible tool for teaching kids and neighbors how to conserve water.

Two rain barrels

Hardcore Greywater

Homes that really make use of greywater will have purple pipes from their bathroom sinks that go into their toilet and then an overflow pipe that will water their gardens. You can also connect the laundry room sink and washing machine to a filtration system that can go into the ground or the garden hose.

Greywater should not be stored for more than 24 hours since the extra compounds in it will start to smell and grow bacteria, according to the environmental group Greywater Action. Again, local zoning and laws must be considered before installing a greywater system. Your township might also ask you, "What is greywater?" If you're not a plumber, always hire an experienced professional.

Will you consider using your greywater in a more meaningful way? Maybe just keep a watering can in the shower? Let us know on Twitter!

Image source: Flickr | Flickr | Flickr

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Why It’s Good

Conserving water takes the stress off our local water bodies from which we harvest our drinking water as well as reduces energy to transport, store, and clean water. Making use of greywater is like water recycling as we use it twice.