Will Bath Water Hurt Indoor Plants?

In today’s world, people are always trying to find new ways to recycle and save the planet. One way you might not know you can recycle is by reusing your bathwater for plants. However, considering there is a variety of unique substances in your leftover bathwater, you might be wondering whether the bathwater will hurt indoor plants.

Using bath water will not hurt your indoor plants if done correctly and for short periods of time. Ingredients in certain soaps can seriously harm your plants, so it’s essential to ensure your particular soap is appropriate before using bath water for your indoor plants.

This article will discuss how to use bathwater on your plants correctly and what you should watch out for when using the bathwater.

How To Use Bath Water on Your Indoor Plants

The term bathwater means precisely what you think; it is the liquid leftover after someone takes a bath and does not drain it. Although it may be frowned upon for you to reuse that water on yourself, it is more acceptable to use it on your plants. 

Using bathwater can be a great watering alternative to help you save on your water bill. It’s a particularly helpful technique if you’re in an area where there’s a drought, and there isn’t much access to water. 

Contents of Recycled Bath Water

The quality of the bathwater may vary, and it will likely contain substances such as body wash, dish soap, and detergent. Luckily, most soil can filter out those contaminants, and sometimes the residue left can function as a mild fertilizer or pesticide. 

If you keep used bathwater in the tub for too long, unhealthy bacteria can grow. To keep bacteria from growing, you should only use bath water for up to 24 hours. You can keep it in your bathtub, sink, or some container such as a bucket. When it comes to watering plants, bath water shouldn’t replace regular water, but it is okay to use it for a short time if needed. 

How Bath Water Affects Plant Health

The Royal Horticultural Society experimented on some plants and found that the use of bathwater for a few weeks didn’t have any adverse effects. However, after six weeks, some plants showed signs of salt stress. 

Plants such as Snake Plants, Ficus, and Monstera plants are known for their resilience to any environment. So, plants such as these could likely go longer with getting watered with the bathwater.

A plant such as the Fiddle Leaf Fig is highly demanding and challenging to keep alive as it is. With this in mind, I wouldn’t recommend using bathwater on a plant such as this. Before using the bathwater, you’ll want to make sure to research how easy it is to handle that particular plant.

Depending on the type of soap and shampoo you use, there could be adverse effects on the leaves. When using the bathwater, pour it directly into the soil and avoid the leaves so that they don’t get damaged by direct contact with the soap. 

Soaps That Could Harm Indoor Plants

If you decide to use bath water to water your indoor plants, you’ll want to be careful about using certain soaps. Soaps can have different ingredients that will have harmful effects on your plants, even if it’s just one time. 

The most common soap ingredients that are harmful are the following: 

  • Sodium hydroxide
  • Sodium laureth
  • Sodium lauryl

Sodium Hydroxide

PubChem describes Sodium hydroxide as a very corrosive chemical, and the ingredient is common in many hygienic soaps. This ingredient is powerful lye and so caustic that it can harm plant tissue. This chemical is in many soaps because it is highly effective for removing dirt and grease.

Plants are covered in a waxy lipid for protection, and sodium hydroxide can eat away at that protective layer. If the plant doesn’t have a protective layer, it will be susceptible to various problems like insects and bacteria that may cause the plant to die. So, double-check the ingredients in your soap before using the leftover bathwater on your plants. 

It is essential to know that bathwater is not the same as dishwater and that you should never use dishwater that has dish soap in it to water your plants. Ingredients in dish soap can be extremely harmful to your plants. 

Sodium Laureth and Sodium Lauryl

Sodium Laureth and Sodium laurel are also chemicals that break down dirt. According to the experts at Medicine UQ, these chemicals are known irritants to human skin after extended use. If it can negatively affect our skin, you won’t want to put it on your plants either.

Dish soaps often have sodium laureth and sodium lauryl sulfate in them. These ingredients dissolve the barriers between water, oils, and dirt, which is excellent for washing dishes. However, this would not be a good thing to put in your plants’ water and soil. 

According to the Laid Back Gardener, a concern regarding sodium laureth and sodium lauryl sulfate is that they contain ethylene oxide and 1.4-dioxane. These chemicals take an extremely long time to degrade and stay in your plants for a long time; this is detrimental to the plants and the overall environment. Even if you rinsed off the plant, the chemicals would remain. 

If you want to learn more about watering your plants with soapy water, you can read my other article here: Can You Water Your Plants With Soapy Water?

Soap From Bath Water Can Deter Insects

In addition to watering your plants with bathwater, it has been found that using particular soap and water mixtures can deter bugs that cause harm to your plants. You’ll want to use soap intended for laundry or bath use, and watch out for harmful additives. 

The easiest way to make a safe soap mixture to deter insects is to follow these simple steps from Home Guides:

  1. Grate one bar of soap into a pot/pan
  2. Add 1 quart of water
  3. Bring this to a boil until the soap is dissolved
  4. Pour the mixture into a type of storage container
  5. When using the combination on your plants, mix one tablespoon of the mixture into a spray bottle full of water.

Using a soap mixture on your plants is a great way to deter insects. Don’t use bar soap with a strong fragrance, though, as this can harm your plants.

Some insecticides are safe for plant use, such as Garden Safe Insecticidal Soap Insect Killer (available on Amazon.com). This product is affordable and completely safe for any plants you may have. The spray is organic and doesn’t have harmful ingredients in it. 

Another great option is the Natria Neem Oil Spray For Plants Organic Disease Control from Amazon.com. This product is primarily made from Neem oil, an ingredient that helps deter pests and can help diseased plants. This spray can help the plant return to good health. 

Watering Plants in the Bath Tub

So, if you’re using the bathwater, you may be wondering if you can put your plants in the tub to water them. The answer is yes, you can. This technique is called bottom watering! It is recommended to water many plants by setting them in water and allowing them to soak up as much water as they need.

You can set your plant right in the bathtub in a pot that has drainage holes so that the water can get through. You’ll want to make sure the water isn’t too deep.

The potted plant should be able to sit on the bottom of the tub—not floating—and still soak up water. A couple of inches of water should be just fine, depending on the size of your plant.

Leave the potted plant in the water for about 15 to 20 minutes. This amount of time will allow the plant to absorb the perfect amount of water it needs. After this, you can return the plant to its regular spot in your home. 

If you are interested to learn more about bottom watering, you can read my beginner’s guide here: How to Water Plants from the Bottom (Beginner’s Guide)


When used correctly and not for long periods, bathwater is not harmful to your indoor plants. You will want to pay attention to the ingredients in the soap that may be in your bathwater. 

Some ingredients such as sodium hydroxide, sodium laureth, and sodium lauryl can break down your plant’s waxy protective layer. 

You can make safe soap into a mixture to create an at-home pesticide. There are also safe products available that you can use. Bottom soaking your plants in bathwater is a great way to make sure they soak up all the water they need.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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