Save Water by Using Washing-Up Water on Your Plants!


All around the world, gardening remains a favorite pastime for people of all ages. This hobby does seem relatively harmless; however, it has been said that over 4.5 billion gallons of water are wasted every day due to evaporation, wind, and runoff from faulty watering practices. Luckily, we will be talking about something that will combat that problem.

Gray water, otherwise known as wash water, can safely water our plants- and could be our holy grail to save water. While our dirty dishwashing water may not be appealing to us, our plants will appreciate us for it!

We will be talking about just this unconventional water-saving method that could save billions of gallons of water every day.

What is Gray Water and How Does it Help plants?

Water conservation is the act of saving or recycling water, as freshwater is becoming increasingly more limited. The use of gray water is a practice brought to the modern public in the late 1980s to save water.

According to scientists, by the year 2050, more than half of the world will live with limited or no access to fresh drinking water (source).

The act of conserving water through household recycling was an unpopular activity. Many believed that all of the drained residential water had been mixed with “black water,” contaminated drainage from toilets, making it unsafe to recycle.

Background on Grey Water

The first county to recognize the significant difference in contamination levels between gray and black water was Goleta County in California.

Goleta’s water district conservation office wrote a letter to the Santa Barbara Board of supervisors asking that gray water be legalized for residential use, as its properties are different from that of “black water.”

The conservation claimed that gray water’s impurities were not heavily contaminated with feces or urine and could be filtered and repurposed safely.

Properties of gray water

Properties of gray water can even make soil flourish, such as phosphates present in detergents that can act as fertilizer.

These findings convinced the board that gray water recycling is a secure conservation method, and by 1992, new laws were legislated, making gray water legal in 17 western states.

Since then, however, conservation in the form of water recycling has grown increasingly popular.

Residential Water Recycling

While conservation systems of greywater can be installed in residential homes, irrigating recycled water directly from the source to the yard, they can be a bit on the pricey side.

These costly conservation systems pump gray water and black water to separate central stations and filter the irrigation system’s gray water.

It is imperative to have separate drainage to the sewer when gray water is not being utilized.

How to recycle residential water – the cheap way

High-end gray water irrigation systems weigh out to be far too complicated and costly compared to manual efforts. Luckily, manually collecting gray water can be just as easy. Conservationists set up buckets below indoor AC units, as they waste lots of water due to condensation.

We never know the worth of water till the well is dry.

Thomas Fuller, Historian

Drip irrigation systems can direct from these buckets, but they can also be used to water manually. Bathwater is a relatively clean source of gray water, usually collected in more significant amounts.

Safely Conserving and Handling Gray Water for use on plants

It is crucial to know where all gray water was obtained as some gray water can contain chemicals harmful to plants and humans.

Gray water should always be handled with care and never contact the eyes, mouth, or skin; if it ever does get on the skin, it is imperative to thoroughly wash hands with warm water and soap.

Gray water containing any food particles can also lead to rodents and bugs in the garden, so it is essential to collect only safe gray water and filter it somehow.

There must also be no sharing of this gray water when conserving, and it cannot get it in any public place. Any stored gray water on an individual’s premises should always be appropriately labeled, and any filtration systems should be specified as well.

Gray Water for use with plants

Just like anything else, some practices should be done for proper usage. Below are some important information on the usage of gray water for plants.

  • It is crucial not to use any unfiltered gray water on edible plants, like vegetables or fruits, as fecal matter and urine traces may be present.
  • With gray water, it is always best to be used within 24-hours of collection to avoid any bacterial growth. Bacterial growth can affect how plants respond to the gray water and can cause plants to wither.

However, this is only one of many ways to create a DIY filter at home; it is straightforward and cost-effective. It will be explained and described in detail near the end of this article.

Gray Water’s Effect on Plants

As Goleta’s water district conservation office once proved, specific properties in gray water aid plant growth.

Gray water can contain traces of skin cells, which can significantly aid plant growth as organic material.

The same way plants absorb properties from manure, they absorb the elements found in gray water.

However, it is still vital to monitor plants to ensure they are still thriving, as gray water can be very high in particular chemicals and may treat each plant differently. Also, be sure to assess any changes to make sure the culprit of the issue is identifiable.

Water-saving tips for plant use in the garden

In addition, to recycling gray water, the conservation of rainwater is just as beneficial.

Many conservationists leave large containers outside, under runoff from their roofing, during rainfall to collect large amounts of water, and others utilize rainwater storage tanks.

Using rainwater for plants

Unlike gray water, rainwater has a longer expectancy to remain free of bacteria. Rainwater being collected is only as clean as the container it has been stored in, so keep that in mind before ingesting any rainwater.

Choosing to opt for water-saving pots is also a great way to conserve water. Water-saving pots don’t drain water from the sides, leaving move water in the soil and requiring it to be watered less.

Your gardens will greatly benefit to having added mulch into it

Adding mulch to gardens can also save water by trapping moisture within the mulch and reducing the amount of watering necessary for surrounding plants.

Mulch is also great for avoiding weeds from sprouting! Compost can also be used and works very similarly by transferring its water supply to the soil it covers.

Using mulch in the garden will not only save water but also prevent soil erosion, weeds and reduce the amount of work required. I wrote an article all about mulch in the garden and you can read that here.

Swapping lawns for rock and concrete for water saving

One of the easiest and most effective ways to avoid excess water usage is by swapping out lawns for concrete or rocks. Even reducing the amount of lawn within one’s yard can significantly reduce the amount of water necessary for upkeeping the growth and color.

Water timer usage can be something to look into for water saving

Finally, keeping a water timer, an electronic device that will increase or decrease water flow when placed into a water line, will prove incredibly beneficial.

Whether freshwater or stored rainwater is being monitored regularly, it is essential to the plants’ health not to be overwatered.

Preventing Bacterial Growth in Stored Water when using it for plants

Bacterial growth can form in gray water anytime after about 24-hours of being collected.

Typical bacterial growth in gray water is algae, which forms when a collection of nutrients is brought to the surface of a body of water.

Like most plants, algae need sunlight to bloom, so keeping storage containers in the dark and even painting storage containers black can help avoid growth.

Mosquito contamination in gray water

Mosquitos are also commonly known to contaminate gray water, as they deem the properties of the water as suitable breeding grounds. It is not safe to ingest mosquitos or their larvae, so it is of utmost importance that they are avoided at all costs.

One way to avoid mosquitoes from entering storage containers is by keeping them in covered, dark places and keeping a layer of olive oil in them.

If mosquitoes manage to get into these containers, the olive oil will keep them from breeding, and because oil floats to the top, rainwater can still be drained from the bottom without oil contamination.

The Future of Recycling and Saving Water when gardening

The act of saving water and utilizing it for gardening purposes is still somewhat of a new practice in the modern age; however, studies are showing that homes implemented with water conservation systems save 15-25 gallons of water every day, ranging from 5,000-9,000 gallons each year, per person!

According to scientists, we only have about 18 years before running out of fresh and clean, usable water, making the need for water conservation even more necessary than ever before.

History is known to repeat itself, and if we have learned anything from the Mayans, we are only given limited water sources.

If water sources become scarce or even contaminated, it could cause much more significant effects to modern life beyond belief.

DIY Filter for waste water when watering plants

A DIY filtration system could be a great option if manual conservation is utilized.

Below is a list of necessary items used in making this filter, followed by instructions on assembly.

Supplies Needed

Most of these supplies can be found in the home goods department, and the rest can be found in hardware stores in your local department stores.

DrillLarge air filter
A large container (stackable)2-inch grommets
A medium-sized container (stackable) with a lid2-inch wide pipes, in whatever length necessary

Next are the building process and instructions of the filtration system.

Instructions to follow

The medium-sized container will be first looked into in this making process.

  • First, holes should be cut throughout the bottom of the medium-sized container. They should be about 2 inches wide and spread apart. It is also necessary to add one hole of the same size on one side of the container.
  • The air filter should be cut to fit in the bottom of the container., leaving enough room on the sides of the air filter that it curves upward and blocks half of the side holes.
  • On one side of the large container, a 2-inch hole should be drilled near the bottom. Insert 2-inch grommets into this hole.
  • Stack the medium-sized container on top of the large container.
  • On the medium-sized lid, drill a 2-inch hole to the top on either side.
  • The top pipe should be connected through the lid and attached to whatever water source is being utilized (i.e., washing machine, dishwater, etc.)
  • The bottom pipe should be connected through the side hole on the larger container. This pipe can be attached to an irrigation system or under a watchful eye, filtered, and utilized manually.

It is also best to have planned the design on a sheet of paper to look at during this process.

FAQ’s on using grey-water for plants

Conclusion Saving Water by utilizing washing up water on your plants!

With the nearing date of the world not having enough clean water to go by, actively looking into avenues like utilizing gray water is a good step.

Many countries have already begun water conservation efforts, and we have quite the catching up to do! There have also been recent studies of the usage of Moringa oleifera or the Mallungay and even sawdust that can be utilized to remove specific pollutants (source). Hopefully, with technology and humanity going hand in hand, we can find more ways to take special care of our water so that everyone in need can easily access it.

If you liked this article, be sure to subscribe in the form below to be notified about future content and releases!

Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

Recent Posts