Can RO Reject Water Be Used for Plants?

Reverse osmosis, or RO, has become a popular method to purify water for home use. However, RO systems tend to produce a lot of reject water, which is essentially the water that has been filtered out but is not pure enough for use. This begs the question: can RO reject water be used for plants?

The Short Answer

Yes, RO reject water can be used for plants, but with some caveats. The main issue with using RO reject water is that it tends to be acidic and lacks minerals that plants need to thrive. Therefore, it is not recommended to use RO reject water as the sole source of water for plants. However, it can be mixed with tap water or other sources of water to dilute its acidity and provide some essential minerals.

The Long Answer

RO reject water is often acidic due to the removal of minerals such as calcium and magnesium. These minerals serve as buffers against acidity in water and help to balance pH levels. Without these minerals, the water can become too acidic, which can be harmful to plants. Therefore, it is essential to monitor the pH levels of RO reject water before using it for plants.

Another issue with RO reject water is that it lacks essential minerals that plants need to grow. While removing minerals from water is the primary purpose of RO systems, some minerals are actually beneficial to plants. These include calcium, magnesium, and potassium, among others. RO reject water can be supplemented with these minerals to provide a more balanced nutrient profile for plants.

One way to supplement RO reject water is to mix it with tap water or other sources of water that contain minerals. This can dilute the acidity of the RO reject water and provide a more balanced nutrient profile. Another option is to add nutrients directly to the water, such as with fertilizers or other plant supplements.

It is important to note that not all plants have the same nutrient requirements, and some may be more sensitive to changes in water pH or nutrient levels. Therefore, it is recommended to research the specific needs of the plants in question before using RO reject water or any other water source.

Conclusion

RO reject water can be used for plants, but it is important to be aware of its potential drawbacks. Its high acidity and lack of essential minerals can be balanced by mixing it with other sources of water or supplementing it with nutrients. However, it is essential to research the specific needs of plants before using any water source, including RO reject water.

Overall, using RO reject water for plants can be a sustainable and cost-effective option, but it requires careful monitoring and management to ensure optimal plant growth.