Softened Water Can Be A Problem for Landscapes and Houseplants

Salt damage to guava from saline or salty
water in the overhead irrigation (water
applied to the leaves)

Q. I'd like to soften the water in our house, or at least get some of the minerals out of the pipes. Culligan-type water softeners are supposed to release a lot of salt into the ground, which I think is harmful for the plants.  You can separate your softened water from your water for the plants but I've heard that is not cheap.  There are other so-called softeners which use calcium or potassium chloride or something else besides salt in the Culligan-type units but it's more expensive.  What should I do?

A. I am not going to talk about the pros and cons of water softened with sodium chloride versus potassium chloride for personal use. This is not my area of expertise but I can speak the subject of watering plants with softened water and your irrigation system.

            Normally, softened water starts after the water from the street has been tapped for your irrigation system. If this is done, it should not be a problem for you. It most likely would be a problem if you have tapped an irrigation system from a hose bib coming from the walls of your house. Many houses have their water softener conditioning water going to every water outlet in the entire inside of the house.

Salt applied to the ground from saline water applied through
drip emitters

            This will mean that softened water is delivered to both hot and cold faucets as well as the hose bibs you use for hoses outside the house. So if you have a water softener and you have some sort of irrigation system attached to a hose bib, then you are most likely watering outside plants with softened or saline water.

            Whenever you use a hose attached to a faucet coming from the walls of your house, then it will be carrying softened water. If you are watering houseplants from an inside faucet and you have softened water, then you are most likely watering them with softened water.

Salt damage to rose leaves from soil salts, not applied to the
leaves through overhead irrigation but salt in the soil

            Is softened water bad? Yes, it can be. If you are using inexpensive water softening salts then this is most likely sodium chloride or common table salt. Sodium is very toxic to plants and can destroy the structure of soils. Chlorides are essential to plants but in high amounts it can also be toxic.

            What to do? As you mentioned, potassium chloride is an alternative water softening salt to regular water softening salt but it is more expensive. In fact, it can be double the price or more. Potassium is a mineral contained in fertilizers and used by plants in fairly high quantities. So potassium chloride would be a better alternative for plants than common water softening salt.

Pitting of the sidewalk from water runoff
from the lawn of water containing salts

            When I installed my irrigation system, I put hose bibs in the landscape that were fed by the pressurized main line of the irrigation system. This way when I watered with a hose I was not using softened water. I avoided using water from hose bibs coming from the house.

            When I watered houseplants, I use distilled or RO water instead of water from the faucets. I mixed a very small amount of houseplant fertilizer in the water so that it had some good minerals in it. This avoided the use of softened water on houseplants which can be very toxic to most of them.