Is Softened Water Bad for Plants?

Updated December 18th, 2023

There are many reasons to have softened water at home. From reducing limescale buildup in pipes and fixtures to keeping your skin and hair softer and cleaner, it can do a world of good in any household. But when it comes to watering your plants, advice can be pretty confusing about whether it is safe to use.

We all know plants help beautify and spruce up our spaces. They can even boost our moods, reduce stress, and improve air quality. But for them to bear these benefits, we have to treat them well – like ensuring they get adequate sunlight, watering them as needed, and using the right kind of water. Hold a sec; “…the right kind of water?” Yes, you heard it right.

Like humans, specific elements in some water types can be toxic to plant health and even cause them to wither and die. For instance, when water softeners use salt to soften water, the salt concentrations left in the water may affect plants over time. Because of this, many plant-loving homeowners are turning away from salt-using softeners for better alternatives.

Now, if you have a salt-water softener that treats all the water entering your home – including the water coming through your garden hose – you might be wondering if your plants are at risk. Luckily, we’ve weeded out the facts regarding softened water and its potential effects on plants. Let’s get to the root of it.

What is soft water?

Softened water is considered water with little or no calcium and magnesium content. As you can probably recall from any of our articles on water softening, calcium and magnesium are the main culprits responsible for hard water. Most water softeners use “ion exchange” to eliminate these minerals, therefore, softening the water. This process involves flushing the source water through a salt solution that swaps the hardness minerals for salt ions. The resulting softened water usually contains traces of salt ions not enough to taste but may not be suitable for plants.

Is soft water bad for plants?

It all depends on whether the softening process involves using salt. See, salt-based water softeners produce softened water by exchanging the hardness ions for sodium ions (salt). Although short-term use is unlikely to be very toxic to plants, it might cause some undesirable outcomes over long periods because:

  • Salt-softened water usually contains small amounts of salt, which can interfere with the plants’ water balance over time. The accumulated salt content “tricks” the plants into “believing” that they have taken up more water than they have, causing them to die of thirst.
  • The salt can build up in the soil and make it difficult for future plants to grow. That’s because salinity acts like a drought on plants, preventing their roots from performing vital activities such as absorbing and transporting water from the soil to other areas of the plant structure where it’s needed to help the plant grow.
  • Salts in the soil can absorb water, resulting in less water being available for the plants to uptake, increasing water stress and root dehydration.
  • A high salt level also interferes with the germination of seeds and can lead to stunted plant growth, smaller-than-usual leaves, marginal necrosis of leaves, or fruit distortions.

Of course, excess salt can cause a lot more damage to plants, some more severely than others, depending on the type of plants and other factors.

How softened water can affect plants

Salt affects different plants in different ways. Some plants are more tolerant to salt, while some cannot function even at low exposure levels. That said, here are some common types of plants and how salt in softened water may affect them:

  • Vegetable gardens: As we mentioned earlier, salt-using water softeners can make it more difficult for plants to absorb moisture from the soil. Besides that, when plants uptake excessive salt concentrations, the salt may directly affect the plants themselves. Once that happens, they may experience symptoms, such as delayed bud break, early leaf drop off, nutrient deficiencies, reduced plant strength and stem growth, etc.
  • Flowers: Studies show that salt in soil can negatively affect plant cells, causing the leaves to become yellow and the flowers to grow much smaller. Although there’s not a lot of salt in softened water, the buildup over time can affect the health and beauty of flowering plants, reducing their vibrancy and overall appeal.
  • House plants: It’s best to avoid salt-softened water for house plants at all costs. Depending on your home’s water hardness level, the level of salt in the water can vary significantly. However, because the soil for house plants is minimal, salt deposits can build up much quicker, damaging the plants’ roots and other parts. And since you probably won’t know how much salt is in the softened water, it can be difficult to make corrections for the damage.
  • Trees: Most trees are naturally large, so how can small salt amounts in softened water damage them? Well, trees are commonly damaged by salts in the soil as well as through evergreen needles. There is a vast number of discussions about whether the salt content in salt-softened water can have an effect on trees over time, but if you’re concerned about the long-term effects, turn off the softener while you’re watering your plants.
  • Aquatic plants: Experts believe that salt-softened water may harm some fish and damage aquatic plants. All the same, the softened water can be beneficial to some types of fish and plants. However, the salt can disrupt the delicate salt balance recommended for aquariums and decorative ponds.

How can you tell if your water is hard or soft?

If you want to know if your tap water is hard, take a look around or reflect on recent events in your home. Have you noticed excess soap scum that, no matter how thoroughly you cleaned and scrubbed, wouldn’t budge? Are you suffering from crunchy hair and dry skin even after using your favorite lotions and hair shampoos? If you’ve been having any of these frustrating experiences, there’s a good chance your water is hard.

Several other telltale signs of hard water include white, chalky residue around your faucets or showerheads, or if your soaps and shampoos (even the most expensive ones) don’t lather well.  While these signs are all indicative of hard water in your home, it’s best to perform a water test. A water test will let you know for sure if you have hard water and whether the water is mildly, moderately, or severely hard.

Whether your water comes from a municipality or you have a private water supply, such as a private well, you can use a DIY home test kit (sold online or at local home centers or hardware stores) to check the water for hardness. Alternatively, you can ask your local water supplier to provide you with the hardness level of the water they deliver. Or better yet, request a copy of their latest water quality report. For even more accurate results (though it might take some time before you receive them), you can send a water sample from your tap to a certified local lab for testing.

Regardless of the method you use, it will give you a good idea of your water hardness level. That way, you can be more proactive about protecting your plants, appliances, pipes, fixtures, and all the other things in your home that often fall victim to hard water and its devastating effects.

So, what’s the solution to keep your plants healthy and happy?

It’s a joy to see your love for plants (the fact that you are reading this article tells it all). As such, we’ve researched a few excellent ways you can spare your precious plants from the damaging effects of high salt content and other harmful minerals potentially present in your water supply. Here goes:

1. Use potassium chloride instead of regular salt.

Potassium chloride is an excellent alternative to sodium chloride. It is a plant nutrient, which means it is perfect for plants and soils. Just add a few potassium pellets in your softener’s brine tank rather than the usual salt, and you’re good to go!

2.   Water your plants with rainwater.

Rainwater is probably a plant’s favorite – if you don’t live in a place with too much pollution, that is. It is often jam-packed with minerals necessary for plant growth and will make your plants grow bigger and healthier than other water types. If you choose to use rainwater to water your indoor plants and individual garden and potted plants, you can collect it in a bucket, barrel, or another suitable container. However, if you have many plants to water, you can purchase a rain collection barrel, which can come with a hose attachment so you can water large amounts of an area with ease. The most significant benefits of using rainwater are that it helps conserve water and is usually clean and naturally soft.

3. Consider installing a second line specifically for watering plants.

Another option is to have a plumber install a separate line to an external connection that you can use to water plants, trees, and landscapes with untreated water but still enjoy all the benefits of softened water in your home.

4. Install a salt-free water softener.

Unlike salt-based water softeners, salt-free softeners produce softened water without using salt (as the name suggests). Salt-free softeners are an excellent substitute for salt-based units since the softened water will not contain any salt that would otherwise damage your plants, all while enjoying the remarkable benefits of having a water softener in your home. That means no more stains, watermarks, or filmy residue on your sinks, bathtubs, and in your toilets, and all the other problems that come with hard water.

Both the salt-based and salt-free versions produce softened water, but it’s essential to know the difference between both types. However, you’ll more likely be happier with a salt-free softener if you want to protect your plants from the adverse effects of salt without missing out on the incredible benefits that come with a quality salt-free water softener.

The best Salt Free Water Softener Alternative for plants

If you decide to go with a salt-free system, we recommend the Springwell FutureSoft FS1 Salt Free Water Softener Alternative. This salt-free softener is a compact, efficient, and reliable unit designed to eliminate hardness-causing minerals from water without using chemicals or salt. Plus, unlike traditional water softeners, it doesn’t require electricity to work, waste water, nor discharge brine into the environment. Instead, it uses a physical process called Template-Assisted Crystallization (TAC), which converts the dissolved hardness minerals into small calcite crystals that remain suspended in the water instead of forming mineral scale on surfaces like hard water does. Also, because the FS1 salt-free softener does not trap minerals in the water, there’s no need for a regeneration cycle to remove the captured ions.

With the FS1 salt-free softener in your home, you can expect the following benefits:

  • Healthier and happier plants
  • Reduced scale buildup in pipes, fixtures, and appliances
  • Easier house cleaning
  • Brighter and softer laundry
  • Longer-lasting appliances
  • Savings on your water and electricity bills (since the FS1 doesn’t need to regenerate, nor does it use electricity)
  • High water flow rates and no drop in water pressure due to the system’s ActivFlo technology
  • UV water purification system add-on to kill bacteria, viruses, and other water-borne pathogens

But if your water comes from a municipality where it’s disinfected with chlorine, our CSF1 Water Filter Salt-Free Softener eliminates chlorine to protect your plants from its corrosiveness to plants. Too much chlorine in water can be toxic to plants, so if you do not have a filter that removes it from the water you use to water your plants, the chemical can accumulate in the leaf tissue. And when this happens, it can result in smaller leaves with a scorched or burned appearance.

If you have any questions about our unique line-up of affordable, reliable, and efficient water softening systems, check out our Water Softeners product page or head over to the Water Filter Softener Dual Systems section. And of course, you can always send us a message or give us a call using the information on our contact us page.

Final Thoughts

Watering your plants is a crucial part of keeping them healthy. However, it’s equally important to use the right water. Using softened water to care for your plants can hinder their growth and development and cause them to wilt and die. To prevent this, use one of the methods we described above to keep your plants in great shape and your outdoor or indoor spaces looking greener and more beautiful than ever before. Your plants will thank you for it.