Will Soft Water Kill My Plants?

Every plant needs clean water, good soil, and a little sunshine to grow. And sure, a green thumb can go a long way, but without the essentials, your plants won’t stand a chance. So first things first, make sure you’ve got the right type of water!

Soft Water, Saltwater, and Rainwater

Whether we’re caring for houseplants or tending to the garden outside, when plant people are asking about soft water it’s usually because they have a home water softener installed. These systems work to remove the calcium and magnesium and other hard minerals that typically come with regular tap water. Instead of living with water that leaves hard water spots on their dishes, or crusty buildup on their faucets, they’re getting soft water—water that doesn’t dry out their skin in the shower, make their hair feel brittle, or lower the efficiency of their water-using appliances.

In order to create soft water from hard water, the majority of water softeners will use salt. As hard water passes through your water softener, the system’s resin beads trap the minerals. Over time, those resin beads get saturated with minerals, and so to regenerate the beads, the softener runs a cycle that flushes them with a brine solution. That brine solution is made by dissolving salt in water, and when that goes through the system, it replaces the hard minerals with sodium ions. Then the water leaves the system, and we get soft water at the faucet!

Sometimes people are worried about the amount of sodium in water that’s coming from a water softener, when in reality, it’s totally negligible. That being said, concerns about plants getting too much salt, or sodium, are still valid. Saltwater can definitely kill plants, and a high concentration of salt in the soil can damage plant roots and prevent them from absorbing water and nutrients. This often leads to stunted growth and could eventually cause the leaves to turn yellow or brown and fall off. However, when we’re talking about soft water, those saltwater problems won’t even come up. Because here’s the thing: Rainwater itself is actually soft water. (And isn’t rainwater just about the best water there is for plants?)

What we refer to as “soft water” is essentially water with low mineral levels. That definition includes sodium, too. So in terms of salt, you should be in the clear. Soft water isn’t the issue. The real question is whether your water is carrying other types of contaminants.

Common Problems with Tap Water for Plants

There are all types of water filtration solutions, and they all serve different purposes. Water softeners are specifically designed to filter out hard minerals. They don’t address anything else, which means that your tap water could be harboring a variety of contaminants that are harmful to your plants, not to mention your own health.

For example, the water might contain varying degrees of heavy metals. The municipal water treatment process just isn’t strong enough to eliminate those risks entirely, especially when it comes to lead leaching into our water from the pipelines. There’s also the problem of having chlorine as a disinfectant in our tap water. Even trace amounts of chlorine can be toxic to plants. (Think about watering them with pool water!)

To prevent these issues, you’d need a whole home water filtration solution. By pairing a chlorine removal system with your softener, and then setting up a drinking water filter in the kitchen, you can help keep everyone hydrated and happy! The best type of water for any living thing should be totally contaminant-free.