It’s perfectly reasonable to be concerned about the water you give your houseplants, but if your tap water is safe to drink, it’s usually fine for your plants too, with a few exceptions. We reached out to a few experts to find out when you should and shouldn’t use tap water for your houseplants.

“About 95 percent of typical houseplants can handle long-term use of tap water, especially if you rinse the potting soil every now and then,” says Tom Knight, owner of ourhouseplants.com. Learn more about chlorine, chloramine, and other potential problems here.

Where does your tap water come from?

Your tap water can come from several sources, depending on where you live. This source may not necessarily be good for houseplants.

Many rural families get their water from a well, so their tap water is well water. However, most people in the United States get their tap water from a municipal or city water system. All city water systems are required to be tested and disinfected for public health reasons, using various chemicals, with chlorine being a common one. Your municipal water company must submit a document called a confidence report annually that lists the processes and chemicals used.

Possible problems when using tap water for houseplants

Chlorine is probably the most commonly used disinfectant for water systems. Other possible chemicals added to tap water are chloramine and fluoride. The small amounts of these chemicals are not harmful to most plants in small doses, but the effects can add up.

“While you can water houseplants with tap water, some of the chemicals it contains, such as chlorine, fluoride, lime and pH additives, can harm plants over time as they build up in the soil,” says Michael Clarke, landscape architect and gardener.

Clarke explains: “If you use a water softening system at home to reduce limescale and care for your skin and hair, the excess salts in the water can be extremely harmful to plants. Over time, the extra sodium in the water becomes toxic to plants.”

How to flush chemicals out of potting soil

Small amounts of chemicals can build up in potting soil and reach harmful concentrations. This problem can usually be solved by rinsing the pot and soil down the sink.

1. Place the plant in the sink and run water until clear water comes out of the drain holes. Set the faucet to a low setting, not a high pressure.
2. Continue flushing until enough water has penetrated the soil to fill the pot three or four times.
3. Leave the pot in the sink for an hour to allow the water to drain completely and avoid making a mess when you put it back in its place.

Benefits of watering plants with tap water

The biggest benefit of using tap water for your houseplants is convenience, followed by cost. Getting water from the kitchen faucet is far less of a hassle than buying a bottle from the store or hauling it off the roof. When it’s easy, you’re more likely to water often and as needed, rather than forgetting or putting it off. It’s also cost-effective. Even in cities with high water prices, tap water is far cheaper than bottled water.

Since most plants can’t tolerate tap water, you’ll probably be fine using it. Plan to flush your houseplants once or twice a year, especially if you fertilize frequently.

Exceptions: Tolerant and sensitive plants

While most houseplants don’t mind tap water, some are more picky. “Mountain palms and spider plants are particularly sensitive to fluoride and you may notice that they develop brown tips over time when exposed to these elements,” says Clarke.

Plants whose natural habitat includes particularly clean water or special conditions are also more likely to be affected. “Generally speaking, these are any plants that are native to special locations like peat bogs. These are any carnivorous plants like Venus flytraps and pitcher plants. Other common houseplants like Calatheas, spider plants and even the peace lily can sometimes show negative symptoms from tap water, such as brown leaf edges,” says Knight.

For these demanding plants, rainwater or bottled water is a better choice because home filter systems cannot easily remove the chemicals they are sensitive to.