I’m all for saving and recycling water whenever possible, including using ‘greywater’ in the garden.
Greywater refers to water that comes from the washing machine, shower or bathroom sink. As long as the soap you use is biodegradable, greywater is safe to irrigate plants in your garden. However, special care must be made when applying it to edible plants.
Use the right kinds of soap and your greywater can actually be a way to fertilize your garden as well as to irrigate!
What Kind Of Detergent is Best For A Greywater System?
What to look for on the label
Look for the words “biocompatible” or “greywater safe” on the label. You want detergents that are free of harmful chemicals that could hurt your plants or soil. Some detergents are not just safe, but actually designed to be part of a greywater system!
Avoid borax (also called boron) and sodium as ingredients as they are toxic to plants. Other chemicals to avoid include chlorine. This is especially important if you’re using washing machine water on your plants – avoid any chlorine or bleach contamination.
They are not harmful in small quantities to humans though, so labels that have these might read “non-toxic”, despite their danger to your garden.
If you do use bleach, be sure to direct that laundry water back into your septic as opposed to the landscape. Thatʻs why approved greywater systems come equipped with 3-way valves, so you can switch back and forth if the need arises.
Some minerals, such as sodium, may not appear to be dangerous, since they are natural. However, if you regularly use water that has increased-levels of sodium in it (because of the soap or detergent solution) it will have an effect on the soil and make it more difficult for water to penetrate.
Itʻs best to avoid powdered detergents since they normally contain high amounts of sodium and stick with the liquid detergents instead.
Some of the top-rated detergents are:
Made from plants, free of parabens and phosphate, and loads of other stuff you want to keep away from your garden (and probably your clothes, too). This is a biodegradable soap that is greywater safe and can be used in the garden.
What I like about this product is that it is easy to find and affordable. Target, Walmart and other grocery stores as well as online thru Amazon, have all been known to carry Ecos Laundry Soap.
Oasis soap is sodium free and becomes plant food as it decomposes in the soil. You heard that right, it actually fertilizes plants as it breaks down. You may think something like that would not be great at keeping clothes smelling fresh and clean, but it excelled at that as well.
This would be my go to soap if it were easy to find. Right now the only place I have found it is on Amazon, sometimes the local natural foods co-op, which is great, but comes at a price. I just pick up the Ecos brand detergent at the local store instead.
Biopac Liquid Detergent is a recommended detergent from the authority on greywater – Greywater Action. It not only is ‘biodegradable’ but it also helps plants to grow.
Look beyond the term ‘biodegradable’ and consider products that are biocompatible. The key of being biocompatible is that it enhances, benefits and doesn’t cause harm to the environment around it, even without decomposing. This is what you’re after: a soap or detergent that is ‘compatible’ with the ecology of your garden.
You can order online, but if, for some reason, you can’t get ahold of a ‘biocompatible’ soap, you can simply use one that says “greywater safe” on the label, too.
Which Plants Is Greywater Safe To Use With?
A good rule of thumb is to use greywater with larger items that have deeper roots. Trees and fruits and vegetables that grow on stalks or climb above the ground are a good start. I say: use greywater on things that grow UP, avoid using on things with lay DOWN, or root vegetables.
One reason for this is because any residue in the water (or tiny particles of food) may directly get on to plants which lay on the ground when using grey water. For plants that grow up, you’re only watering the soil around them and the water must travel through their root and stem system to reach the edible parts.
| Good for Greywater Use | Avoid with Greywater |
| Trees (all types)Fruit treesTomatoesEggplantCornPapayas, BananasFlowers | Lettuce/Greens/KaleStrawberriesCarrotsPotatoesWatermelons/MelonsButternut Squash or PumpkinsOnions/Garlic |
Best System To Recycle Washing Machine Water
I prefer to use a very basic irrigation system with greywater from my washing machine. Why? Because anything complex usually has high cost and maintenance issues associated with it.
A direct system (also called laundry-to-landscape) works great, saves the water and doesn’t cause me any hassle, so it’s convenient for me to implement.
I go over all about how to install a Laundry To Landscape Greywater System in this post here.
One of the advantages of a direct system from your washing machine is that it doesn’t require you to make any major adjustments to your plumbing system or pipes.
Washing machines already have an ‘outflow’, which goes to your sewer system. All you do is change the direction away from your sewer and outside of your home, to your garden. It’s pretty easy to set up, using a 3 way valve and pvc pipes or tubing.
Two things to consider:
(1) divert the water throughout your garden or it will just make one big puddle where it exits the pipes. You can add ‘arms’ or ‘branches’ in your irrigation system to ensure it spreads throughout your garden;
(2) set up a diverter valve at your washing machine. This way, if you do need to wash with bleach or other harmful chemicals, you can divert that water to your sewer system and save the damage to your garden.
You can easily set up your own greywater irrigation system off of your washing machine. As long as you choose biocompatible detergents you can feel good about recycling your laundry water straight into your garden or fruit trees with a direct laundry-to-landscape system. The environment, your plants, and your wallet will thank you!
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