One of the main disagreement with the use of reverse osmosis water for home consumption is that it strips all minerals from the water, including those that we need. I have already explained how to add mineral back to reverse osmosis water in my article on “is reverse osmosis water good or bad for you”. An interesting thought is whether RO water is safe for plants. That is something I have not thought recently and is keen to explore the truth behind this question.
Benefits of using reverse osmosis water for plants
For growers, one important action they need to do is to balance out the different kinds of nutrients that plants will need in order to grow well. Traditional water contains lots of impurities that make such balancing act difficult at best and inaccurate at worst. What reverse osmosis can accomplish is to take out all impurities such that growers are starting from a clean base. This not only makes calculating the minerals balance easier but also removes any potential reaction with fertilizers.
Disadvantages of using reverse osmosis water for plants
One con of using RO water is the amount of water wastage you can incur, although these can be minimized via some of my tips in this article on reducing water wastage with ro water. If you have a large garden, prepare to see your water intake shot up when you switch from normal to reverse osmosis water. In particular, water wastage is around 1:3 ratio for the average reverse osmosis system.
Another con is that ro water is missing some salts that can be beneficial for the plants. To remedy this problem, we need to add fertilizer salts back to the ro water. The quantity required is 1 teaspoon per gallon of RO water. Any form of fertilizer salts will be fine.
When should you use reverse osmosis for your plants
The answer to this question lies in the current TDM of your water. If it is anything around 150 PPM, I suggest that you switch to ro to see better results in your plant growing. Having such a level of TDM means your plants will have a harder absorbing the beneficial nutrients since it has to grow through the rest of the junk minerals in the water. If the TDM of your water is really high, such as 300 PPM, you are looking at least 1000 TDM if you want to inject another 700 TDM of nutrients into the water. That amount of TDM will lead to nutrient lock up and salt up, which is a big no no for any plant growing.
Conclusion
Is reverse osmosis safe for your plants? I would say it is a definitely yes. Although there are disadvantage, they can easily managed such that you enjoy only the benefits of using ro water for your plants or garden.