Can I reuse the waste water from reverse osmosis (RO) to water my plants?

Q:

I have a question about making the most out of waste water. I have been using reverse osmosis-treated water for some time and am worried about the amount of waste water that comes out of it. I would like to find a use for this water and have a few options and ideas: leave it in the soil (which I think might increase the salinity of the soil, resulting in unproductive soil); use it for washing clothes or utensils; or recycle in another filter for further treatment. While researching ways to reduce the waste water and reuse the water that comes out of the RO treatment, I came across one of your articles and was impressed by the way you deal with issues and explain things so precisely. Can you help with my issue?

A:

We recommend waste water be used on lawns, mature trees, shrubs and other non-sensitive plants. Reuse of waste water is somewhat dependent on the contamination of source water; source water with high parts per million (ppm) levels (more than 400) will produce much higher ppm waste water than source water with a lower ppm. The question posed mentioned the possibility of increased salinity; this would only be an issue if source water had salinity to begin with, which is relatively rare, or if the RO system was being used to filter water from a water softener. The only way to remove softener salts is to use reverse osmosis, the process of which would definitely concentrate that salt and could potentially build up in soil, causing damage even to non-sensitive plants. If you have a softener, it’s best to send the RO waste water down the drain. If you do not have a softener, try using it on trees, shrubs and lawns. Avoid using it for washing the car or clothing or dishes, as concentrated, hard water can cause spotting and wear out clothing.

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Written by Jennifer Casey
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Jennifer Casey loves her two dogs, her husband, the amazing garden he grows, and living in the country. In that order. Crafting, reading, and cooking food she picks from the garden are her favorite ways to spend her time.  Full Bio