What Is Greywater? How to Collect It & Use It Safely - Public Goods

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What Is Greywater? How to Collect It & Use It Safely

When we turn on water-guzzling appliances such as washing machines and dishwashers, not all of those gallons need to go down the drain and into the sewers.

laundromat washing machines

There is some excess runoff that can be saved as greywater, water that is too dirty to drink or bathe with but can still be reused to hydrate plants and lawns, among other purposes.

Relying on greywater will lower the cost of your water bill and contribute to water conservation efforts. If you love being sustainable and hate the thought of your grandchildren growing up in an arid wasteland where humanity is constantly fighting over a limited water supply, it’s time to learn more about greywater use.

How to Use Greywater at Home

There are several ways to incorporate greywater into your daily routine. You may not be able to drink it, but you can reuse this dirty H₂O to help lead a more sustainable and environmentally-conscious lifestyle.

Irrigating Plants and Yards

Most greywater enthusiasts primarily rely on this wastewater for irrigation purposes — specifically to sustain their plants and yards. You don’t need clean potable water for most plants, so dirty water reused from your household appliances or morning shower should help them flourish.

Some people dump all of their greywater in a bucket and use it to irrigate their plants and lawn at the end of the day. This strategy is ideal for ornamental plants, shrubs and flowers but is not recommended for food crops.

Extra Water for Your Toilet

Greywater isn’t only good for irrigation. This non-potable water can also be used in the home!

For instance, instead of wasting gallons of water every year, why not put some of it in your toilet so it can be reused for flushing? This method of utilizing greywater is the easiest because you don’t need to worry about the quality of the water. Unlike the plants in your yard, your toilet has handled much worse…

If Your Home Has a Hot Water Heater

If you have a hot water heater, deposit your greywater in the tank when it needs to be filled. This conservation strategy will save you money on your water and heating bills.

But, Before You Reuse That Water…

Before employing greywater for outdoor irrigation purposes, make sure you are using household products that are “greywater-friendly.” This label means the products don’t have harsh, unnecessary ingredients such as chlorine bleach and sulfates. These chemicals can kill your plants and poison the soil in your yard.

To ensure that all of your greywater can be used immediately, buy bathroom and cleaning products that are considered “greywater-friendly,” such as the following:

If there isn’t a greywater-friendly claim on the product, check the list of ingredients on the back and look for the following chemicals:

  • sodium lauryl/laureth sulfates
  • ethanolamines (MEA/DEA/TEA)
  • chlorine bleach
  • parabens
  • phosphates
  • phthalates

If you don’t see any of these, the product is most likely safe for use.

Finally, to avoid creating problems for yourself and your home and ensure you’re using greywater safely, follow these guidelines:

  • Do not store wastewater for more than 24 hours. It might start to smell bad.
  • Do not touch greywater. It is usually safe, but it can develop harmful pathogens.
  • Do not allow your greywater to pool on the ground or runoff. These outcomes can create breeding grounds for mosquitoes.

Always consult local water authorities before beginning your use of greywater.

How to Collect Greywater From Around Your Home

So, where exactly can you get your greywater from? Believe it or not, there are viable sources of water that can be collected from several household appliances. Here are a few:

Washing Machines

Some washing machines are able to divert excess laundry water into a storage container or irrigation system. Your machine might be a valuable source of greywater, so consider contacting a water authority or plumber to help you develop a laundry-to-landscape irrigation setup.


Your dryer might have a compartment where it stores all the water it extracts from wet clothes. This compartment is usually easy to remove and dump. Sometimes you might need to empty it to prevent overflowing, so why not make the most of that chore?


Again, this utility depends on the machine. Our recommendation is to always seek assistance.

Kitchen Sink

Your kitchen sink also produces a bountiful supply of water that can be reused in most cases. However, greywater from the kitchen tends to contain food particles and grease, so reusing this water often requires a more complicated system than other sources.

When You’re Running Fresh Water and Waiting for It to Heat Up

When you heat up water in the sink, tub or shower, it usually needs to run for a bit before it reaches the temperature you want. This waiting period is the perfect opportunity to gather some water that can then be used for plants and such. Next time you run your shower, for example, try saving that initial cold water in a bucket.

This type of water is technically not greywater. You probably don’t want to drink it, though, so make it useful in other ways.

Drinking and Cooking Water You Didn’t Finish

Your family finishes dinner, and there are a bunch of water glasses scattered around the table. The water has been sitting still for too long to drink safely, but it seems like a shame to dump it in the sink.

These ounces add up, so toss them in your toilet or yard instead. There might be other sources, too, such as canteens, extra ice, tea kettles and pots that boiled water but did not contain greasy food.

Condensation and Drops from Air Conditioning Units

Have you ever seen a big puddle or damp spot beneath one of those air conditioning units people shove in their windows? If you have one and live on the ground floor, you can gather water by placing a container under it to collect condensation drops and water leaks. It may not seem like much, but it all adds up.

Consider Installing a Greywater System

People who are more serious about water conservation have installed greywater systems that streamline the process of distributing the water. One option is the branched drain system, which divides the flow of wastewater into smaller branches so it can be reused in various ways. These networks of pipes and valves can be expensive and difficult to implement, so think about whether you would be able to afford the commitment.

When you install a greywater system on your property, it can be used directly for irrigation purposes — delivered straight to your garden or yard. There are also recycling systems that capture and filter wastewater, making it easy to recycle and reuse the water. A greywater recycling unit is typically installed by a plumber, connecting to household applications and stored next to your house.

It’s best to consult local government water authorities and ask for help with the installation of this kind of water system. You can visit the Water Wise Group website to find nearby greywater system dealers and installers, although there is no guarantee there will be listings in your state or zip code.

Making a Big Difference from the Comfort of Your Home

Water consumption affects all of us. Perhaps it is one of those rare, relatively apolitical issues we can unite around. Regardless of your beliefs, minimizing waste is both cost-effective and good for the environment and society.

“If each American saves just one gallon of water today, that would be enough to supply a city like Detroit for almost a week,” said green designer and artist Pablo Solomon, whose home won an award for natural preservation and restoration.

Green business expert Shel Horowitz argued it would be easy for most U.S. households to reduce their water use without much effort or expense. Horowitz also highlighted evidence of entire communities — such as Earthship Biotecture — adopting greywater systems.

By collecting and distributing greywater around your home, you can save money and become more mindful of your water use. Take a moment to consider the amount of wasted water you’re leaving behind the next time you do laundry, take a shower, or leave a glass of water lying out a little too long.

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