Like humans, plants all need water to grow and oftentimes need specific soil conditions in order to grow healthfully. When you are watering your household plants, it is best to use the watering information for the specific plant. We offer general information in this blog post. No matter the water you use, watch for stunted growth of your plants. If this is the case, it may be necessary to change the type of water used.
It is best to water plants with rainwater or hard tap Water depending if you’re watering inside or outside plants. Having less than 10 grains per gallon (gpg) of hardness in hard tap water is ideal. The hardness level is unlikely to be a serious danger to neither a plant nor its soil conditions. Since soft water is 0-1 gpg, this doesn’t mean you can use soft water. The sodium levels can have an effect on soil conditions and salt can build up over time within the soil. If your water has a high hardness level, over 10 gpg and your home uses a water softener, then more sodium is needed to remove the hardness therefore more sodium is in the water. Some homeowners will use reverse osmosis water for watering. The mineral content and contaminants are removed at a high degree and offer your plants a great chance for growth.
For outside watering, it is neither recommended nor economical to use softened water unless using to prevent iron staining on concrete, siding, or brick. Reason being, the water softener will regenerate more often using more water and more salt costing more money. Depending on the hardness of your water and the amount of salt used per regeneration in your water softener, softened water might be adequate to kill the grass.
Water Quality Association – https://www.wqa.org/learn-about-water/faqs#Is%20softened%20water%20safe%20for%20plants?
Better Homes and Garden – https://www.bhg.com/gardening/houseplants/care/watering-houseplants/