How to Use Grey Water in the Garden

Collecting and saving grey water can be an excellent way to combat drought conditions and reuse water for your garden. vilax/Shutterstock

If you've ever watched your garden struggle through a summer drought, you know the pain of seeing everything from annuals to a treasured plant passed down from grandma wilt, shrivel and die.

But you don't have to lose any of them to the relentless heat that leaves the dirt dry as dust.

Even if soaring summer temperatures and a lack of rain lead to outdoor watering restrictions or even an outright ban, there's still a way you can legally quench the need of thirsty plants. It's called grey water — water from kitchen or bathroom sinks, bathtubs or washing machines that some municipalities still confuse with wastewater — that you can safely capture and re-route to the landscape through manual or mechanical means. (And yes, there are some restrictions on this, depending on where you live, but we'll cover that in more detail below.)

There are two basic ways to re-use grey water in the garden. One is the tried and true do-it-yourself method of collecting indoor water in buckets, bottles, pans, cans or anything that will hold water and carrying it to the garden. The other is to find a group that will work with you or teach you how to turn your current household plumbing into a sustainable system that can provide irrigation for your landscape.

The DIY Bucket Method

Water in a bucket next to a daisy
Collecting grey water using buckets and containers is a low-maintenance way to reuse your water, but it requires a good bit of labor. Lena Lir/Shutterstock

While collecting grey water in buckets isn't the most efficient way to re-use non-potable water, it has several advantages. Anyone can do it, and it doesn't cost anything. All you need is a bucket, a little bit of effort and a lot of determination. A dose of ingenuity can also be helpful! To help you get started — and perhaps fire up your imagination for other creative ways to re-use household water — here are some DIY ways to save grey water indoors.

  • Warm-up water: Put a container under the faucet to collect cold water while you wait for the water to heat up.
  • Kitchen sinks: Place a pan in the sink and rinse vegetables and wash dishes in the pan.
  • The stovetop: If you steam or boil vegetables, don’t pour the water down the drain. Instead, let it cool and pour it on that hydrangea grandma gave you.
  • Rinsing out wine and other bottles: If you rinse bottles before placing them in the recycle bin, pour the rinse water onto thirsty plants.
  • Bathroom sinks and bathtubs: Scoop water from daily routines into buckets.
  • Showers: Place a bucket in the shower to catch water as it warms up and while you shower.
  • AC condensation: Run a hose from condensation spouts to garden plants, moving the hose from plant to plant as they show signs of summer stress.
  • Leftover coffee: This is liquid gold for acid-loving plants (think azaleas!) so pour leftover coffee onto these plants — including some houseplants such as Phalaenopsis orchids instead of pouring it down the drain.
  • Bottled water: You paid good money at a convenience store for that bottle of water. If you didn't finish it, empty a partial container onto a plant instead of into the sink.
  • Dog bowls: When you're freshening your pooch's water, don't pour water remaining in a partially filled bowl into a nearby sink. Pour it into a container for outdoor use instead.

Professional Grey Water Irrigation Systems

Greywater Action volunteers work to install a grey water irrigation system
A grey water irrigation system can save you a lot of time in the long run, but it will require some elbow grease to install. Greywater Action/Facebook

If the bucket method of collecting grey water sounds like a lot of work, that's because it is, but there are alternatives. For example, Greywater Action is a collaborative of educators who work with policymakers and water districts to develop codes and incentives to reduce household water use and promote a sustainable water culture. Greywater Action develops simple and affordable low-tech residential systems that favor gravity over pumps to pipe grey water from the kitchen, bathroom and laundry room to the landscape. As a result, homeowners can maintain a sustainable backyard ecosystem that enhances food production and ornamental gardens and also provides shelter for wildlife.

Greywater Action offers a five-day installation training session and includes a regional directory on the website to help you find an installer in your area who has taken their course.

Installing an Irrigation System Yourself

"If you can't find an installer in your area, we have tips on the website for people like ecologically minded landscapers who could easily learn how to install our system," said Laura Allen, a Greywater Action co-founder and author of the book "The Water-Wise Home: How to Conserve, Capture, and Reuse Water in Your Home and Landscape." Homeowners can also take an installation course by watching webinars or attending in-person training in the Bay area or in Los Angeles.

Typically, the simplest system involves the washing machine and doesn't require any plumbing modifications. "You just take the machine discharge hose and connect it to a diverter valve," Allen explained. "One side goes to the sewer system and the other goes to an irrigation system. That system is really the easiest because you don't have to change the plumbing."

To figure out how much irrigation water this will put on your garden, multiply the number of gallons of water your machine uses by the number of loads of wash you do a week, Allen says. The only time this system doesn't work very well is when the washing machine is in the middle of a home built on a slab foundation or when the yard slopes uphill.

Washing machine water attachments
A washing machine is the simplest grey water system you can install, and it doesn't require any changes to your plumbing. ppart/Shutterstock

Is It Worth the Money?

Installing a grey water irrigation system will pay for itself over time because you'll reduce overall water consumption. How much time it will take to cover the cost of the system through savings on your water bill will depend on how much water you use.

Another way to look at the economics of a professional grey water system is to think of it as drought insurance for your plants, Allen said. "Think about if your community was on water rationing because of a drought and you would potentially lose some plants due to them not having enough water. Your grey water system could save your plants."

Know the Rules Before You Install

It's also important to understand the code and permit requirements for a grey water system in your area. Many states and communities have not upgraded their codes to allow for professional grey water systems, she said. "The majority of states have very restrictive codes that make it economically not feasible for the average person to be able to financially comply with them. Some states don't have grey water codes at all, she said. In those cases, you have to apply for special permits to install a grey water system. The problem, she said, is that many states still consider grey water to be same as sewage. She's optimistic that with more areas experiencing water shortages, this misperception will change. See Greywater Action’s codes and policy page on its website for more information about grey water codes in your state. The group also monitors state regulations and posts updated information on its Facebook page.

However you use grey water, remember that whatever you're putting into your water will wind up in your garden. Because of that, Allen advises using soaps and detergents that are plant-friendly. These are products that don't contain high levels of boron and salt, which can be harmful to plants.

The Do's and Don'ts of Upcycling Grey Water

Water poured on a sapling
Not all plants like grey water, so be careful where you use your collected water. Gyuszko-Photo/Shutterstock

The group offers excellent guidelines for the do's and don’ts of re-using grey water on the website, but here are some highlights:


  • Use household water from sinks and showers even if there's some food, grease, or hair in that water.
  • Use grey water on other vegetable plants, fruit trees and berries, but don’t let the water touch the edible parts.


  • Use water from the toilet or water you've used to wash diapers. Water containing fecal matter is called black water.
  • Use grey water on root vegetables or small lettuces and other leafy greens where the edible portion of the plant touches the ground.
  • Allow grey water to run off into streams, ponds or other natural water sources.
  • Attempt to water your lawn with grey water unless you're ready to spend tens of thousands of dollars on a system; even small lawns are too big to be watered effectively with grey water.

Reasons to Upcycle Grey Water

As you're thinking about which approach to take at your house, here are some facts about household water use that might surprise you. The information below is from the Environmental Protection Agency (EPA).

  • U.S. households use an estimated 29 billion gallons of water daily.
  • The average American family of four uses 400 gallons of water per day.
  • On average, about 70 percent of household water is used indoors.
  • Nearly 9 billion gallons of the 29 billion gallons used daily, or 30 percent, is devoted to outdoor use.
  • In summer months, or in dry climates, a household's outdoor water use can be as high as 70 percent.
  • More water is used in the bathroom than in kitchens or laundry rooms. (A toilet alone can use 27 percent of household water!)