As you consider making greener choices within your home, you may have heard about greywater systems. Like solar panels or rainwater harvesting, a greywater system is a great way to benefit from resources already being used within your home. Read on to learn how to create your greywater system or download our helpful Greywater Recycling booklet.
So, what is greywater?
Greywater is water from washing machines, showers, bathtubs, and bathroom sinks. It is wastewater that may contain some soap, salts, hair, suspended solids and bacteria, but that is clean enough to water plants. Keep in mind that water from toilets, kitchen sinks, or wash water from diapers is not considered greywater in California.
Greywater (treated or untreated) is not the same as municipal recycled water, which is highly treated wastewater from a centralized treatment facility. Recycled water can be used for landscape irrigation, toilet and urinal flushing, cooling, and other approved uses.
What can greywater do for you?
- Decrease potable water use by 16 to 40 percent, depending on the site (Cohen 2009).
- Decrease water and wastewater utility bills.
- Diversify water supply portfolio by providing an alternate source of water for landscape irrigation, reserving potable water for drinking purposes.
- Reduce the energy (approximately 2 watt-hours per gallon of water) and chemicals needed to treat wastewater.
How do you know if your home has the right onsite conditions?
You can install a greywater system for outdoor irrigation without a permit if you meet all of the following requirements:
- Greywater comes from the washing machine only.
- System does not alter household plumbing (you access greywater from the hose of the machine, not by cutting into the plumbing)
- It is for a one- or two-unit residential buildings only.
- Greywater system follows the 13 guidelines set forth in the California Plumbing Code (referenced here) .
What are the Greywater Do’s and Don’ts?
Greywater is a unique source of water and must be used differently from potable water and rainwater. You must:
- Keep your system as simple as possible. Simple systems last longer, require less maintenance, use less energy, and cost less. Systems with pumps and filters require more commitment and regular maintenance.
- Install a diverter valve at a convenient location to allow for easy switching between the greywater system and the sewer system.
- Match the amount of greywater directed to your plants with their irrigation needs. Many products contain salts and boron, which can harm plants.
- Do not store greywater for more than 24 hours. If you store greywater, the nutrients in it start to break down and create bad odors.
- Minimize contact with greywater. Greywater can contain pathogens. All systems must be designed so that water soaks into the ground and is not accessible by people or animals.
- Infiltrate greywater into the ground; do not allow it to pool or run off. You'll need to know how fast water soaks into your soil to properly design your system. Pooling greywater can provide opportunities for mosquitoes to breed.
Choosing Greywater Compatible Detergents
Not all detergents are made the same. Look for detergents that are greywater friendly, meaning they are suitable for irrigating your landscape and won’t harm your plants. Here are a few sample products:
Greywater Friendly Detergents:
Oasis Laundry Detergent (liquid)
ECOS liquid detergent
Vaska (also makes commercial laundry detergent that is compatible with commercial washing machines)
Trader Joes Liquid Detergent
Puretergent
BioPac
Greywater Friendly Landscaping
Certain landscape does better with greywater systems than others. Larger plants, such as trees, bushes, and perennials, are easier to irrigate with simple greywater systems than smaller plants. Turf grass, made up of hundreds of individual plants, is the most difficult to irrigate with greywater- we don’t recommend it. Remember you can safely irrigate any food plant so long as greywater doesn’t touch the edible portion of the plant (no root crops).
Other perennials that thrive on greywater include edible shrubs and vines such as raspberries, thimbleberries, blackberries and their relatives, currants, gooseberries, filberts, rhubarb, elderberry, passion fruit, kiwi, hops, and grapes. Blueberries love acidic soil so you’d have to choose pH neutral soaps or use acidic mulch.
Tell Landscapers, Gardeners, Contractors
Be sure to inform anyone who works in your yard about your new greywater system. Show where the pipes and irrigation points are so that the pipes don't accidentally get punctured or the mulch basins altered or buried. Otherwise, your system could be unintentionally damaged by people who don't understand how it functions.
As our environmental crisis becomes more dire, we need to be a more active part of the solution. By taking existing resources and making them dual purposes, we are becoming more conscious inhabitors of our earth.
Thank you for reading our Greywater 101 Guide! For futher reading, download our free Greywater Recycling booklet, which will give you all the tools you need to create a greywater system in your own home. Written in partnership with DIG Cooperative, this booklet outlines the dos and don'ts of building a laundry to landscape system, including best practices. If you're considering implementing a greywater system in your home, click the thumbnail to download.
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