Water is essential to plant growth, but not all water is created equal. In order to make sure your plants are getting the best possible watering experience, it’s important to understand the different types of water and what each does for your plants.
Reverse osmosis water is very good for plants. Many botanists and home gardeners say it’s the best water you can use. Reverse osmosis removes the contaminants that are harmful to plants such as chlorine, herbicides, pesticides, and heavy metals. For delicate plants like violets and orchids, RO treated water is a must. Reverse osmosis also removes beneficial minerals so you will have to use a fertilizer to add back the nutrients your plants need.
In this blog post, we will take a look at reverse osmosis water and its effects on plants. We will discuss the pros and cons of using reverse osmosis water for irrigation so that you can make an informed decision about what’s best for your garden and houseplants.
Related articles:
Is Softened Water Good Safe for Plants?
Is Brita Filtered Water Good for Your Plants?
Table of Contents
Reverse Osmosis – What Is It?
Reverse osmosis is a widely used treatment method for water. It is a process that removes dissolved solids, particles, and other impurities from water by using pressure to force water molecules through a semipermeable membrane.
The contaminants, which are larger than water, are retained by the membrane. Clean water passes through. The end result is clean, filtered water that is free of contaminants.
Related articles about reverse osmosis:
The Definitive Guide to Whole House Reverse Osmosis Filter Systems
Complete Guide to Under-sink Reverse Osmosis Filters
What does reverse osmosis remove?
Reverse osmosis removes a wide range of contaminants from water. This includes dissolved minerals, bacteria, viruses, and even some larger particles. The size of the pores in the semipermeable membrane determines what will be removed from the water.
RO can remove the following contaminants.
| Chemical | RO Removal Rate |
| Sodium | 90-95% |
| Calcium | 93-98% |
| Magnesium | 93-98% |
| Potassium | 90-95% |
| Iron 2 | 93-98% |
| Manganese 2 | 93-98% |
| Aluminum | 93-98% |
| Copper | 94-99% |
| Nickel | 93-98% |
| Zinc | 93-98% |
| Strontium | 93-98% |
| Cadmium | 93-98% |
| Silver | 93-98% |
| Mercury | 93-98% |
| Barium | 93-98% |
| Chromium-6 | 94-99% |
| Chromium-3 | 94-99% |
| Lead | 94-99% |
| Chloride | 90-95% |
| Bicarbonate | 90-95% |
| Nitrate3 | 85-90% |
| Fluoride | 90-97% |
| Phosphate | 93-98% |
| Chromate | 90-95% |
| Cyanide | 90-95% |
| Sulfate | 93-98% |
| Boron | 55-60% |
| Arsenic + 3 | 70-80% |
| Arsenic + 5 | 94-99% |
| Selenium | 93-98% |
| Radioactivity | 93-98% |
| Bacteria | > 99% |
| Protozoa | > 99% |
| Ameobic- | > 99% |
| Cysts | |
| Giardia | > 99% |
| Asbestos | > 99% |
| Sediment/turbidity | > 99% |
Reverse osmosis filter components
RO filters consist of a pre-filter, semipermeable membrane, and a post-filter. The water is first passed through the pre-filter, which removes suspended particles and turbidity from the water. Some systems include a carbon filter that removes chlorine and other chemicals from the water.
The water then passes through the semipermeable membrane, where impurities are removed. The membrane is the critical component of the RO system. It is made of a thin, synthetic material that has microscopic pores. These pores allow water molecules to pass through, but they block the passage of dissolved minerals, bacteria, and other impurities.
Finally, the water is passed through the post-filter, which removes any remaining particles from the water.
Benefits of Using RO Water for Plants
Removes most contaminants
The main benefit of using reverse osmosis water for plants is that it provides them with clean water that is free of contaminants. Common impurities found in water that can harm your plants include herbicides, insecticides, chlorine, and heavy metals.
These impurities can damage plant roots and leaves, and even kill your plants. RO water removes most of these impurities, providing a safe source of water for your plants.
Protects you from contaminants
If you grow vegetables, then using RO treated water will ensure you are not exposed to harmful contaminants that could be present in your water supply.
Some of these contaminants, such as lead and arsenic, are taken up by the plant roots and accumulate in the fruits and vegetables. This can be a serious health hazard, especially for young children and pregnant women.
By using RO water for your plants, you can protect yourself and your family from these harmful contaminants.
Improves plant growth
Another benefit of using RO water for plants is that it can improve plant growth. This is because RO water contains fewer dissolved solids than other types of water.
Dissolved minerals, such as salt, can build up in the soil and stunt plant growth. Too much salt can kill your plants. By using RO water, you can help prevent these problems and improve plant growth.
Complete control of water quality
RO treated water has essentially no minerals in it, including the beneficial ones. You will likely need to add nutrients and minerals (i.e., fertilizer) to your plants to keep them health. Because the only supplements your plants receive are what you add, you know exactly what is in the water and can control the quality of it.
Disadvantages of RO Water for Plants
Removes beneficial minerals
Reverse osmosis removes essential minerals that plants need to grow – calcium, magnesium, nitrogen, potassium, and phosphorous. Removing these important nutrients can lead to stunted plant growth, and in some cases, death.
Acidic water
The process of reverse osmosis creates water that is more acidic than neutral. This can be harmful to plants, as it can change the pH balance of the soil and make it difficult for plants to absorb nutrients. Fortunately, the buffering capacity of most soils makes this issue go away.
Cost and maintenance
Reverse osmosis systems are not cheap, and they require regular maintenance to keep them running smoothly. If you are thinking about using reverse osmosis water for your plants, be prepared to make a significant investment upfront.
Various Water Sources for Your Plants
When it comes to watering your plants, you have a range of options to choose from. You can use tap water, rainwater, or even water from a well. Each of these options has its own set of pros and cons that you should consider before making a decision.
- Tap water: Tap water is acceptable to use for most plants. However, it contains chlorine or chloramine that some plants are sensitive to.
- Distilled water: This type of water has been boiled and the steam has been collected and condensed back into water. Distillation removes all of the contaminants as well as the beneficial minerals.
- Rainwater: Rainwater is the best type of water for your plants as it is the most natural and is free of virtually all contaminants. The only drawback to rainwater is that it can be hard to collect enough for all of your watering needs.
- Spring water: Spring water is another great source of water for your plants. It is naturally filtered and contains minerals that are beneficial to plant growth. The only downside to spring water is that it can be expensive.
- Aquarium water: Water from your fish tank is great for your plants. You remove harmful chemicals like chlorine and ammonia from the water when you set up your fish tank. This type of water also contains nitrogen and beneficial minerals for your plants.
- Softened water: Softened water is OK for some plants, but many houseplants are sensitive to the higher levels of sodium. You should limit your use of softened water to only those plants that are tolerant to it.
- Well water: Well water can be a great source of water for your plants, but you need to test it first to make sure it is free of contaminants and the pH is acceptable.
- Reverse osmosis treated water: RO water is the purest water you can use for your plants. It is free of all beneficial minerals, so you’ll have to provide those separately. Additionally, RO water has a low pH and may need to be adjusted before using.
- Reverse osmosis wastewater: The brine waste from your RO system contains all of the chloramines, salts, and heavy metals that were filtered out of your water. This type of water can be toxic to plants, so it should be avoided.
Now that you understand the different types of water available to you and the pros and cons of each, you can make an informed decision about what’s best for your garden and houseplants.
Under-sink reverse osmosis filter
Here is the under-sink reverse osmosis filter I installed in my kitchen. You may interested in something similar for your home.
FAQs
What can I add to RO water for my plants?
Since reverse osmosis removes beneficial minerals that your plants need, you should add them back. This includes calcium, magnesium, nitrogen, potassium, and phosphorus. Many fertilizer mixtures contain these essential minerals.
Is reverse osmosis water good for houseplants?
Reverse osmosis water is very good for houseplants. It is purified to remove salt, herbicides, and pesticides that can harm your plants. Since it is devoid of all minerals, you may need to add fertilizer to your houseplants to ensure they are getting the nutrients they need.
Is RO water good for orchids?
RO filtered water is good for orchids. Orchids are sensitive to many of the impurities in tap water, so using reverse osmosis water can help keep them healthy. You’ll need to add fertilizer to provide your orchids with the nutrients they need.
What is the best type of water for plants?
The best type of water for plants is rainwater. It is naturally filtered and free of contaminants. However, it can be difficult to collect enough rainwater to meet all of your watering needs. Alternatively, you can use well water or spring water. These types of water are also naturally filtered and contain minerals that are beneficial to plant growth.
What is the difference between distilled water and reverse osmosis water?
Distilled water is water that has been boiled to remove all impurities. Reverse osmosis water is water that has been filtered to remove impurities. Both distillation and RO remove all of the contaminants as well as the beneficial minerals.
Final Take
Reverse osmosis water is a great choice for watering your plants. It is pure and free of contaminants that can harm your plants. However, it does not contain any minerals that are essential for plant growth. You’ll need to add fertilizer to your RO water to ensure that your plants are getting the nutrients they need.