Should You Water Plants with Reverse Osmosis (RO) Water?

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Your indoor plants don’t get the benefit of regular rainfall, and you’re probably wondering if it’s safe and beneficial to use reverse osmosis water for plant watering purposes.

In this guide, we’ve answered the question, “Should you use reverse osmosis water for plants?”

πŸ“Œ Key Takeaways:

  • Reverse osmosis water is purified filtered water that has an extremely low total dissolved solids (TDS) concentration.
  • Reverse osmosis water is good for plants because it doesn’t contain any harmful chemicals, heavy metals, or other impurities found in a normal tap water supply.
  • However, RO water lacks essential minerals, many of which are beneficial to house plants.

πŸ€” What Is Reverse Osmosis Water?

Let’s start with a quick definition of reverse osmosis water, since knowing what this water is will help you to understand its effects and potential benefits when used to water plants.

Reverse osmosis water is drinking water that has been treated in a reverse osmosis water filtration system to remove virtually all total dissolved solids (TDS), making it pure and contaminant-free.

The RO filtration process sends water through a semi-permeable membrane, which has tiny microscopic pores that allow only water particles to filter through. Reverse osmosis removes heavy metals, chemicals, dissolved minerals and salts, microorganisms, and much more.

Reverse osmosis water has no minerals

πŸͺ΄ Is Reverse Osmosis Water Good For Plants?

Yes, reverse osmosis water is considered good for plants – especially sensitive plants – because it doesn’t contain any traces of impurities that could hinder plant growth and gives you complete control over the nutrients and minerals that you provide to your plant.

You might have heard that soft water (produced by a water softener) is not good for watering plants. However, reverse osmosis water is better than soft water because softened water may stunt plant growth by adding too much salt to the soil. RO-filtered water is sodium-free, so it doesn’t feed your plant with any unnecessary impurities.

βœ… Potential Benefits of RO Water For Plants

Here are some of the benefits of using water from reverse osmosis systems, instead of normal tap water, to water your plants:

Gives You More Control

You’ll probably want to feed your plants with fertilizer and plant food from time to time to encourage healthy growth.

This is easier to do when you know exactly what your water contains, since you know that RO water is free from all minerals and salts.

You have complete control over the nutrients and impurities that are absorbed by your plants.

Free From Harmful Contaminants

The obvious benefit of using reverse osmosis water for your plants is that RO water is free from all potentially harmful contaminants that are found in trace amounts in drinking water, such as chlorine, herbicides, and heavy metals.

Using pure RO filtered water for your plants means you won’t accidentally damage or kill your plants due to problems in the roots or leaves.

Reverse osmosis membrane
How the RO Membrane Works to Block TDS

May Improve Plant Growth

Another related benefit of using reverse osmosis water for plant watering is that this water doesn’t contain any dissolved impurities that could build up in your soil and stunt plant growth.

So, your plants should grow more quickly and healthily when they’re fed with water from an RO system compared to normal tap water.

Protects You From Contaminants

If you water your home-grown fruits and veggies with tap water, the trace amounts of chemicals, metals, and other contaminants found in your water will end up inside your produce.

Most people would rather not consume even low levels of dangerous contaminants, and using RO water for your plants eliminates this risk because your plants are only taking in pure water molecules.

⛔️ Possible Setbacks of RO Water For Plants

You should also be aware of the potential downsides of using water from RO filters on your plants:

Lacks Healthy Minerals

The RO process is so effective that it removes all the bad stuff and all the good minerals from your water.

Plants grow better when they receive nutrients like calcium, magnesium, phosphorus, potassium, and other minerals. If your plants can’t absorb nutrients from your water, their growth might be stunted.

Healthy minerals found in water

Low Water pH

Water from a reverse osmosis system creates mildly acidic water with a low pH, which may upset the soil’s pH balance and reduce a plant’s ability to absorb minerals.


Buying a reverse osmosis water treatment system for your home is an expensive task. Most RO systems for under-sink or countertop installation cost upwards of $250.

Even the cost of buying bottled water treated by reverse osmosis would quickly add up.

πŸ†š Reverse Osmosis Water vs Distilled Water For Plants

Reverse osmosis water and distilled water are essentially the same end product. The only difference is how they’re made.

While reverse osmosis water is made by membrane separation, distilled water is produced by the distillation process (evaporation and condensation of water molecules, leaving the impurities behind in a separate chamber).

RO and distilled water are both purified water sources, so they have the same benefits and setbacks when used for watering plants.

Reverse osmosis system and distiller

🧐 So, Should You Use Reverse Osmosis Water For Plants?

Ultimately, the answer is yes – you should use reverse osmosis water for your plants.

What we know about RO water suggests that, despite its lack of beneficial minerals, it can support healthy plant growth and prevent problems associated with harmful contaminants that could damage your indoor plants.

You can buy bottled reverse osmosis water from most grocery stores and some hardware stores.

Or, you can create RO water at home for free if you install a reverse osmosis system. We recommend doing this if you plan to use a lot of RO water around your home, not only for watering plants but also for drinking, using as aquarium water in your fish tank, and filling your iron and steamer, making baby formula, and more.

πŸ“ Other Possible Water Sources For Plants

Let’s finish off by looking at the other possible water sources for plants, and whether or not we recommend them:

  • Tap water – Most people use tap water for their plants. This water is generally acceptable, but may damage delicate plants due to its chlorine or chloramine content.
  • Rainwater – Most plants indoors and outdoors thrive when they’re watered the natural way: with rain water. However, during certain times of the year, your rain water supply may be lacking, and you’ll have to find an alternative water source.
  • Distilled water – As we mentioned earlier, it’s also good to purify water with distillation and use it as an alternative to reverse osmosis water for your plants.
  • Softened water – This water source isn’t the best for house plants because it contains the same impurities but lacks essential minerals and has a higher sodium content.
  • Natural spring water – This is a great water source for plants because it contains all the beneficial nutrients with minimal impurities because it’s naturally filtered.
  • Well water – Water from a private well is also naturally filtered, but it might still contain contaminants that are harmful to plants, or it might not have the ideal pH for your plants.

Related: Is well water good for plants?

Watering plants with soft water

You should know have all the knowledge you need to choose the best water source for your plants, whether this is reverse osmosis water or another water type.

  • Laura Shallcross
    Senior Editor

    Laura is a passionate residential water treatment journalist who holds an undergraduate degree in Print Journalism and a master’s degree in Creative Writing. Over a span of 5 years she's written on a range of topics including water softening, well water treatment, and purification processes.

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