How To Recycle Gray Water

by heather

Think of how often we waste water. There’s the water that gushes down the drain while we’re waiting for it to warm up in the shower, the water that disappears when we lightly rinse vegetables, and the water that’s used to rinse our clothes. Yes, we need this “graywater” to perform our daily household tasks and cleaning, but it’s also water that we could be reusing in our lawns and gardens.

John Russell of Watersprout and DIG Cooperative (as quoted in the Oakland Tribune here) says that the average person produces 30 gallons of graywater per day. And, the University of Georgia estimates that by recycling graywater, we could be saving 25-40% of water that can then be used for consumption.

With more and more states experiencing droughts every year, recycling our water to make it go further is becoming ever more important.

The Difference Between “Black Water” and “Gray Water”

Many people don’t know that there is anything called “Black Water”. But, there is. Here’s the rundown:

When you wash clothes, clean vegetables, brush your teeth, or take a shower, you’re only lightly contaminating the water. This water is then considered gray water, since there’s not much wrong with it. This water can easily be reused.

When you’re washing a cutting board that you just chopped meat on, flushing the toilet, or rinsing a cut of salmon, this is considered black water. The reason is because this water is now heavily contaminated with feces, or other bacteria like E. coli or salmonella.

Graywater is somewhat easy to reuse. Black water, however, is not. Black water should never be recycled; it needs to go to a waste water treatment facility to be cleansed.

The Benefits of Recycling Water

Reusing your graywater means you’re saving money on your water bill because you’re using less.

It also means you’re using less fresh water for things like watering your grass. This reduces the strain on your local treatment facility, saves energy (because less water has to be pumped to your home) and means that more fresh water is available in your community for drinking and cooking.

How To Recycle Your Graywater

The good news about recycling your graywater is that you can try it at your home for free and go from there.

Graywater systems range from the practically free (putting buckets in your shower or kitchen sink) to the expensive (custom collection systems that divert the water to an outdoor holding bin for filtration and reuse).

It’s important to keep in mind that for most of us, water is cheap. It’s a precious resource that’s dwindling, to be sure, but as of right now we’re not paying for water’s full value.

This means that the cost-benefit analysis of a free, more labor-intensive system versus an installed, more expensive system is going to be a no-brainer: a free or cheaper system is usually the way to go. Many people who recycle their graywater bootleg it anyway (especially in California, where the legalities are so complex that it makes it almost impossible to recycle water for less than $5,000 or $7,000).

So, let’s look at how to recycle your graywater for free (or cheap). Your only investment might be hoses or buckets, and some elbow grease.

1. Air conditioning

If you use window-mounted air conditioning units, you know that condensation builds up and drips every day the system is running. Well, placing a bucket underneath each unit is a great way to reuse this water.

2. In the shower

Buckets can also be used in the shower; when you’ve got the tap on waiting for the water to warm up, a bucket can collect this cold water, which can then be used to water your garden.

Some people have also attached a hose that runs from their bathroom sink to their toilet tank. Every time you wash your hands or brush your teeth, this water then goes into your toile tank for flushing.
3. In the laundry

You can recycle your laundry water easily by hooking your washing machine’s drainage hose to a large drum in your backyard. Water recycling site Greywater Guerrillas has complete instructions here.

4. In the kitchen

You can easily recycle the water from your kitchen sink by loosening the P-trap (the U-shaped pipe under your sink). By disconnecting the P-trap, you’re allowing the kitchen sink water to drain directly into a bucket you place there. Simply twist the P-trap a bit to the side, and make sure you leave some water in there (the water helps keep the gasses at bay from your sewer system).

Rubber-band a plastic bag around the P-trap and leave it be. You’ll want to empty your kitchen sink graywater daily (either onto your lawn or use it to flush with). It’s work, but most of us could use the exercise.

Some people also install a very small sink that is used only for graywater. The small sink is where they was their hands, rinse veggies, or rinse dishes. If you already have a double sink, you can allow one pipe to drain into your graywater collection bucket underneath, and let the other drain into your main line for treatment.

Graywater to Avoid

All household water is not created equal. Your graywater should not have any of these materials in it:

  • Cleaning materials that contain boron
  • Thinners or solvents
  • Bath salts
  • Bleach
  • Drain openers (like Drano)
  • Artificial water softeners
  • Swimming pool water
  • Rinse water from greasy or oily things
  • Never wash diapers and then use that water for graywater; this poses a health hazard


Most of the sites I consulted while doing research for this article also gave a long list of precautions. It’s easy for people to get sick from graywater (due to bacterial build-up) so make sure you do plenty of your own research before installing a system.

Here are a few precautions to keep in mind:

  • Every state has different rules and regulations when it comes to graywater recycling. Some states, like California, have extremely strict regulations. Others, like Arizona, don’t. Make sure you know your own state’s regulations before installing a system.
  • If you’re using your graywater in your garden, make sure you don’t allow the graywater to touch the edible parts of the plants. Using a drip irrigation system is best.
  • Many dishwashing soaps contain phosphates. Phosphates can actually be good for your lawn (adding nutrients to your soil), but if the water leaks into local wetlands or streams, it can be damaging. The best thing to do is to use biodegradable dish soaps, like Seventh Generation.
  • Most of your graywater will need to be filtered in some way, especially if you’re rerouting it to a drip-irrigation line (larger particles in the graywater can easily clog your irrigation lines). This doesn’t have to be complex, however. Simply use a nylon hose or window screen at the point the water leaves your home into the outdoor system.
  • Never spray your graywater; drip irrigation systems are best, as well as using a regular garden house (without a nozzle).
  • Don’t store your graywater more than 24 hours. As far as I can tell from my research, there has never been a documented case of human illness resulting from graywater. But, it’s better to be safe than sorry. Storing graywater allows bacteria to grow, which isn’t good for anyone. So collect it and use it quickly.

Further Reading

These sites have more information if you’re interested in recycling your graywater:

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instant cash loans June 30, 2009 at 3:07 am

I found very informative. The article is professionally written and I feel like the author knows the subject very well. keep it that way.

Chris August 14, 2009 at 2:22 pm

This is a very interesting option. I have a question: if done incorrectly, could you accidentally create a sinkhole in your backyard?

Do you have to watch how many loads you do in one day so as not to saturate the ground? How many square feet of yard to you need to spread the water around?

gaylord November 23, 2009 at 10:22 pm

this site is cool!

MysteryPerson January 7, 2010 at 6:21 pm

Wow I am 10 and im usin this sight and it helped me a little. I need to find out zHow greywater is turned into safe drinkable water

MysteryPerson January 7, 2010 at 6:36 pm

for homework

wolfescape January 2, 2011 at 2:19 pm

awesome. u r ten! i am ten too. i am in sixth grade doing a science project. about greywater. this site helped me a lot

Randy January 28, 2011 at 4:38 pm

GVii manifold saves about 40 gallons of washer machine water everytime you wash by adding a auxillary drain that attaches to the drain hose.The manifold is attached to the end of the aux line, which waters your lawn through four water for more info.Thanks

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