Can You Water Your Plants With Soapy Water?

Soapy water constitutes a large portion of wastewater coming from every household. Environmentally conscious initiatives call for recycling this water source for non-potable use, like gardening. However, many people wonder if it’s okay to water your plants with soapy water.

You can water your plants with soapy water as long as it does not contain bleach or other chemicals that can be harmful to your soil and plants. You can remove these toxic substances by using a filtration system and designing an underground irrigation system.

There are plenty of ways to recycle soapy water and make them useful for agricultural needs. This article will take you through the factors to consider before using soapy water for your plants, and the benefits and downsides of doing so.

Important Considerations Before Using Greywater to Water Plants

Soapy water or greywater coming from households has huge potential for reuse, especially for your garden or lawn needs. 

Most communities in the US have wastewater treatment facilities that manage wastewater coming from businesses and residential areas to make it less toxic to the environment. However, some facilities may be more advanced than others.

As a result, not all treatment facilities can remove hazardous waste from greywater to make it safe enough for gardening needs. It may still contain excessive amounts of nitrogen, phosphorus, and other pollutants, which may be harmful to plants.

If you have the means to treat your own wastewater at home, you will be able to control what goes into your garden. It is not that easy, though.

There are several factors to consider, including the following:


Many people make homemade soap insecticidal sprays by diluting dish soap in clean water and spraying the solution on plants to get rid of insects. This is safe for plants as long as it isn’t used too frequently.

However, if you intend to water your plants with soapy water for watering and not for insecticidal purposes, you need to consider and control where the soapy water comes from.

Every household generates large amounts of greywater. It makes up roughly 75% of the wastewater that goes into water treatment facilities. Most of this greywater is dirty water that contains soap residues and other contaminants.

Soapy water at home can come from the following: 

The safest soapy water source for your plants is the one that comes from the washing machine because you can control what kind of detergent you use. There is also less risk of introducing other chemicals or pathogens from clothes—besides, the detergent will get rid of most of them.


Knowing the contents of soapy water is one of the most crucial things to consider when thinking about using it to water your plants. It can help you decide how much treatment is necessary to make it safe for plant use.

Untreated soapy water cannot be used directly on your plants. It most likely contains toxic components that can kill your plants, worsen their appearance, or significantly reduce the quality of their produce.

As the name implies, soapy water generally contains soap residues.

Depending on the source, it may also contain residues from the following: 

  • Bath soap
  • Shampoo
  • Hand soap
  • Facial wash
  • Toothpaste
  • Laundry detergent
  • Dish soap or detergent
  • Bleach
  • Cosmetic products

In addition to these, untreated soapy water may also carry some contaminants, such as:

  • Bacteria
  • Fungi
  • Food particles
  • Grease
  • Fats
  • Oil
  • Human waste
  • Blood

Since you cannot tell what exactly goes into your greywater or soapy water, it is best to assume that it contains at least a few of the contaminants mentioned above. Based on this approach, you can select the best filtration system.

Access to an Efficient Filtration System

If your local community has a filtration system in place for similar-minded neighbors who want to recycle wastewater for a more sustainable environment, you can check the local regulations to see if you can tap into the system.

Otherwise, you can set one up at home. There are several greywater filtration devices available on the market, but they can be costly. Some people resort to designing their homemade filtration system, which also works well but may be less effective.

This video shows how you can set up a DIY greywater filtration system at home:

Either way, it’s best to invest in an efficient filtration system and direct it to an underground irrigation system. This way, you prevent leftover contaminants from touching the edible parts of your plants.

Benefits of Repurposing Soapy Water for Plants

A large number of people all over the world have started reusing their soapy water for garden use because of its benefits.

Here are some of them:

It Can Cut Down Your Water Bill

If you have a large garden, you’ll know how much money you can save by recycling soapy water and using it to water your plants. The amount of money you can save largely depends on how much water you usually allot for your garden needs.

It may be costly to set up your own filtration system, but the amount you can save in the long run is pretty promising. Nevertheless, you will also need to consider the maintenance cost of your filtration system.

It Helps With Water Conservation

In addition to saving money on your water bills, using soapy water for your gardening needs can also help conserve water, especially in areas prone to water shortages and droughts. 

Plants need a steady supply of water to thrive, and humans release large volumes of wastewater daily. Recycling this wastewater for non-potable use can help a lot in conserving potable water for sanitary and dietary uses.

It Contains Beneficial Nutrients for Plants

Wastewater from households has large amounts of nitrogen and phosphorus, which are essential macronutrients for plant growth. In addition, some soaps contain potassium salts instead of sodium salts. Potassium is another mineral that’s vital for plants.

As long as you can filter out the harmful chemicals and pathogens from soapy water, these nutrients can safely nourish your soil.

What Are the Risks?

Even though many people use soapy water on plants and encourage the practice, it is important to understand the risks that come with it so you can address them.

That way, you can protect your garden and yourself from potential risks, which include:

Additives in Soaps and Detergents Can Be Harmful to Plants

As discussed, you should know where your soapy water comes from and what goes in it before deciding to use it in your garden. 

Although nitrogen, phosphorus, and potassium are good for your plants, additives in soaps and detergents can be toxic to them. For instance, bleach contains high levels of sodium, which can negatively affect your plants’ ability to take up essential nutrients.

Chlorine, which is present in most home cleaning solutions and detergents, also negatively affects plants when it accumulates on the roots or leaves. It can also eliminate beneficial soil microorganisms when applied to the soil in high concentrations regularly.

Potential Damage to Your Plants’ Leaves

Many people make soap sprays to get rid of insects in their gardens. However, these homemade insecticides are typically diluted dish soap, which contains chemicals that degrade oils and fats. Sadly, they can also degrade the leaves’ outer waxy layer.

Commercially available insecticidal soaps are specially formulated to be safe on plants and effective against insects or pests. They are also reasonably priced, so you may want to use them instead of homemade soap sprays.

Pathogens May Survive and Cause Diseases

Soapy water may contain chemicals from cleaners that can kill off pathogens, such as bacteria and fungi. However, disinfectants in soapy water are highly diluted, so many pathogens will be unaffected by it.

Once these pathogens get to the fleshy and other edible parts of your plants, they can cause diseases to those who handle or consume them.

Final Thoughts

Using soapy water to feed your plants can be beneficial economically and environmentally. However, you need to consider several factors, such as the source and the content of the soapy water, to ensure that it is safe for your plants.

Review and weigh the benefits and risks provided in this article. They may help you decide whether or not it’s worth trying soapy water on your plants.

Alexander Picot

Alexander Picot is the founder of and its lead content writer. He created the website in 2022 as a resource for horticulture lovers and beginners alike, compiling all the gardening tips he discovered over the years. Alex has a passion for caring for plants, turning backyards into feel-good places, and sharing his knowledge with the rest of the world.

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