Can I Water Plants with Softened Water?

Is Softened Water OK for Plants, Lawns, & Gardens? blog header

Softened water can do a world of good in a home. From reducing the amount of soap needed to wash clothes and dishes, to extending the life of a water heater, and saving on energy bills. But does softened water bode well for indoor plants and outdoor gardens?

What about the salt?

Most water softeners utilize an “ion exchange” process where calcium and magnesium (minerals that make water hard) are exchanged for either sodium or potassium chloride in order to soften the water.

The amount of sodium or salt in your household water (after processing through a water softener system) can vary depending on the hardness of your water, but it certainly isn’t “salt water”. In fact, on average, those that own a water softener get less than three percent of their daily sodium intake from drinking softened water.

Keeping Indoor Plants Happy

But if you’re worried that the extra sodium from softened water may be hard on your plants, here are a few alternatives:

  • Collect and water your plants with rainwater. You can collect rainwater in aWhite Tulips barrel or even a plastic garbage can at the bottom of a downspout. Collecting rainwater not only conserves water, but rainwater is usually quite clean. And FYI, rainwater is considered “naturally soft water” because it does not contain a significant amount dissolved minerals.
  • Some plants cannot tolerate chlorinated tap water. If your water seems to have a high level of chlorine (you’ll know by the strong chlorine taste or odor), let the water sit in your watering can for a few days to dechlorinate.
  • Use bottled water to water houseplants–but this can be rather expensive.
  • Use water from a reverse osmosis tap to water your houseplants. After the initial cost of the RO unit, reverse osmosis water is generally very inexpensive—just pennies per gallon.
  • Use potassium chloride instead of regular salt (sodium chloride) pellets in your softener’s brine tank. Potassium is a plant nutrient and is fine for plants and soils.

Keeping Lawns and Gardens Happy Outside

For outdoor watering, most water softeners have a bypass valve that allows you to temporarily bypass the softener to access untreated water for your plants. Refer to your softener’s owner’s manual or contact a water treatment specialist in your area to learn more.

You may also consider having a separate line to the outside tap installed by a plumber. This outlet allows you to water plants, trees and landscape with untreated water, but enjoy all the benefits of softened water in the home. 

Mainly, look to your plants for clues. While calcium and magnesium (found in hard water) can be helpful plant nutrients, too much of a good thing isn’t so good. Some plants don’t do well when watered with “hard water”. On the other hand, some plants have a difficult time with softened water. So pay attention to your water quality and look to your plants for clues. 

Oh How Does Your Garden Grow?

Gardening can be a lot of fun. But outdoor and indoor plants can prove to be finicky. So water quality aside, here are four tips that might prove helpful when watering household plants, lawn and gardens:

Water in the morning, if possible. By watering in the morning, the moistened soil has a chance to dry out during the day. Plants that stay damp during the cool evening hours have a greater chance of being damaged by fungal or bacterial diseases. 
Water with tepid water. Plants like tepid water. Each time you finish watering, refill your watering can and let the water sit. That way, the water will be the right temperature when go to water again. 
Don’t over water: Before watering, check the plant soil with your finger. Watch for wilt, but don’t overwater. Plants that are overwatered will look limp and the leaves will begin to yellow and fall off. Plants that don’t get enough water will also look limp, but the leaves will appear dry and brittle before falling off.
Know Your Plants:  Each plant is different so figure out your plants’ growing season. Some plants are very active in growing during the fall and winter months but are slow growing and almost dormant over the summer. Others grow rapidly during spring and summer, but are mostly dormant during the fall and winter.

Not sure what kind of water you’re giving your plants right now? Find out if your household’s water is hard, soft, or something in between. Download WaterTech’s HARD WATER GUIDE to learn the tall-tale signs of hard water and what can be done about it. Or contact a local authorized water treatment professional to find out what’s in your water.

Hard Water Guide cta


  • I have a beautiful lawn that I am wanting to maintain well for the Summer. I have been looking for information to see if a water softener will affect my lawn, and it looks like it won’t, but I still have to keep an eye out. One thing that I was told was to water at night, but now I’m seeing to water in the morning, so I will have to test it out.

    • My lawn was affected by our water softener. I would recommend using the bypass

    • claudia ramirez

      Don’t do it, it will kill your plants. In learning the hard way. I just got one and my poor lemon tree has yellow spots. Look for yellow spots in the tips of all plants.

  • What about soft water using potassium pellets?

    • Isaac Linton, CWS I

      Haven’t found any definitive studies about the affects of potassium chloride on plants, but many gardeners feel seem to feel that using water softened with potassium pellets (to water plants) is a better alternative.

  • My lawn guy always says to water at night after sun goes down to prevent burning.

  • My lawn guy always says at nite after sun goes down to prevent burning

  • Your lawn guy is half right…except that night watering can lead to fungal diseases in lawns. Best time to water is early morning.

    • Agreed. I’d rather have my plants burned by the sun a little bit then have them taken over by fungal diseases. I water early morning before the sun is at it’s high point to avoid both issues.

  • I can’t find anyone answering whether the the softener “exchanged” exhaust water is Ok for plants. In theory it should actually be good, filled with carbonates and magnesium, i.e. very “hard” water. But I want to make sure.
    I’ve set up the softener to only work on the hot water in the house, which, I think, strikes a good balance between the appliances typically using hot water and humans (and plants) usually using cold or mixed water for consumption.

    • Isaac Linton, CWS I

      Watering with the exchanged water isn’t good because of the small amount of sodium that’s in the water.

      • Isaac, do you mean it is too small or do you mean the remaining amount is still a problem? I’ve measured the hardness of water, and it is very hard. I don’t have any means at hand to measure the sodium or chlorine content there. From the scarce info I could find, the backwash water may contain significant amounts of sodium and chlorine. Chlorine, however, should vent out, if I leave water stand for several days, right?

  • A new flower bed I built failed to thrive several plants died, I moved 2 to new location, made no difference.
    By passed the new water softener. Everything recovered.
    Moral of the story, don’t put salt on the potatoes til they are cooked.