Is Tap Water Actually Bad for Your Plants? We Asked the Experts

There are a few different ways to water houseplants. Maybe you grab a watering can and give your plant babies a quick drink, or you give them an occasional deep watering to get that soil really hydrated. Maybe you fill up a sink or bucket and let them soak up water from the bottom.

When it comes to the source, though, chances are that you’re using water from your tap. But is that always the best option?

Is tap water safe for your plants? Here’s what one horticulture expert says, with tips for ensuring your water will keep your houseplants lush and healthy.

Is Tap Water Safe for Plants?

Yes, tap water is safe to use on houseplants—with a few caveats.

“All water is safe to use on houseplants. It just depends on how you use it,” says Clay Stradley, horticulturist at Longwood Gardens, a public garden in Kennett Square, Pennsylvania.

Municipal water supplies are typically treated with chemicals like chlorine to kill germs and fluoride to prevent tooth decay. These are generally harmless to houseplants, though exceptions like orchids and peace lilies may be sensitive to these additives.

Bromeliads benefit from rainwater rather than tap water in their central cups. Using rainwater, distilled water, or demineralized water on carnivorous plants like Venus flytraps, sundews, and pitcher plants is also important.

Hard water, which contains high amounts of dissolved calcium and magnesium, can also cause issues for houseplants, preventing them from taking up nutrients properly.

Many people remedy hard water with water softeners, which use salt to remove those excess minerals from hard water. However, the buildup of salts in your plants’ soil can affect growth or even kill your plants.

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Signs Your Tap Water Isn’t Working for Your Plants

Browning Tips

“Brown edges or spots that are sometimes crispy are the most common indicator that your plant is experiencing stress from tap water,” says Stradley.

Plants like calatheas, marantas, and orchids can develop these issues in response to chlorine or fluoride in tap water.

Yellow Leaves

The high levels of minerals in hard tap water can actually prevent plants’ roots from taking up the nutrients they need.

That includes iron, a deficiency of which can lead to yellow leaves with green veins.

Stunted Growth

Tap water that’s high in salts due to a water softener will harm and eventually kill your houseplants over time, first by preventing them from absorbing nutrients from the soil and then by removing moisture from roots at high concentrations.

This issue may show up as slow growth and an overall dull appearance, or it may look similar to signs of root rot.

Salt Buildup

Keep an eye out for salt buildup on your houseplants to prevent stunted growth and more serious issues. Salts appear as a yellow or white residue on the soil surface. They can also accumulate on the outside of pots made with unglazed clay, such as terracotta.

“Rinsing off the plant and flushing the soil with clear water will rinse out the excess salts from the soil,” Stradley recommends.

Use rainwater or water from a tap that’s not connected to your water softener to do this.

How to Ensure Tap Water is Safe For Your Plants

• Assess your plant collection: “Set yourself up for success by knowing which plants can have a higher sensitivity to tap water,” says Stradley, noting that it may not be practical to find tap water alternatives for every single plant in a large collection. Instead, add a marker like a colored sticker to each sensitive plant’s container.
• Learn where your water comes from: Stradley advises home gardeners to educate themselves about their tap water, whether it’s supplied by a local municipality or a private well. Stradley also notes that the pH of tap water isn’t typically related to houseplant issues.
• Let tap water sit out overnight: If you’re concerned that chlorine may be affecting the appearance or health of certain plants, Stradley recommends filling a watering can or other vessel with water and letting it sit out overnight. The chlorine will evaporate before you water your plants the next day.
• Filter your tap water: The same strategy doesn’t work for fluoride, however. A reverse osmosis system can filter the majority of minerals and additives like fluoride out of your tap water, making it ideal for plants, but the average countertop pitcher filter or faucet filter isn’t effective.

Alternatives to Tap Water

• Rainwater: “Rainwater is considered the best for watering plants, but can be variable in quality depending on where you live,” Stradley says. It can also be difficult to collect in quantity, so it’s best used on sensitive houseplant varieties.
• Distilled water: Distilled water is purified to remove 99.9 percent of minerals, making it ideal for highly sensitive specimens like carnivorous plants. However, Stradley cautions that deionized water should be avoided because it can harm houseplants.
• Bottled water: “For very special plants, bottled water may be a good option, but it’s necessary to read the label before using to ensure there are no additives in the water,” Stradley says. Make sure the water isn’t deionized or sourced from a municipal supply rather than a natural source like a spring or well.
• Dehumidifier water: Dehumidifier water isn’t as pure as distilled water, but it’s okay to use on ornamental and indoor plantings.