Protect your plants from potentially harmful chemicals and minerals.

Like all living things, plants need water to thrive and grow. But the type of water you use on your plants can have a significant impact on their health, vitality, and appearance. While it might seem convenient to simply fill your watering can from the kitchen tap, water from municipal sources can contain a variety of minerals and chemicals, such as fluoride and chlorine, to which many common houseplants are surprisingly sensitive. If given the wrong type of water over time, certain houseplants may develop unsightly brown edges and brown tips on their leaves, and in severe cases, may experience stunted growth or decline in overall health. To keep your plants healthy, vibrant, and thriving for years to come, gardening experts share their insights about the best types of water for houseplants and provide practical advice on how to improve tap water if it’s your only available option.

The Best Types of Water for Houseplants

Rainwater and filtered water are the most suitable types of water for most houseplants, according to experienced plant care experts and horticulturists. These water sources provide the hydration plants need without the potentially harmful additives found in treated municipal water.

Rainwater

Collecting rainwater for your plants is both an environmentally sustainable practice and highly beneficial for plant health. Clean rainwater is naturally free of salts, chemicals, and the various additives used in municipal water treatment processes. Perhaps most importantly, rainwater naturally contains nitrates and other beneficial compounds that can actively help your houseplants thrive and grow more vigorously.

You have several options for collecting rainwater, depending on your living situation and the volume of water you need. For those with just a few houseplants, small containers such as buckets or large bowls can be placed outside during rainstorms to collect water. For more serious plant enthusiasts or those with extensive collections, something more substantial like a dedicated rain barrel connected to your home’s downspout system can provide a steady supply of rainwater throughout the growing season. Regardless of the collection method you choose, it’s essential to keep these vessels clean and free of algae, debris, and mosquito larvae, which can develop in standing water.

During the winter months when rain may be less frequent in many regions, melted snow can serve as an excellent alternative water source. Simply bring clean snow indoors in a container and allow it to melt naturally at room temperature. Like rainwater, melted snow is free from the chemicals and minerals found in tap water, making it a gentle and effective option for your houseplants during the colder months.

Filtered Water

Filtering your tap water is a very feasible and practical solution, especially if your houseplant collection doesn’t require an enormous volume of water on a regular basis. Many houseplant specialists and experienced indoor gardeners prefer to water their plants exclusively with filtered water to remove chlorine and fluoride, and to prevent the gradual buildup of minerals from salts and heavy metals in the soil. This mineral accumulation, which you would inevitably get from using water straight out of the tap, can lead to a crusty white residue on the soil surface and can eventually affect the plant’s ability to absorb nutrients properly.

There are numerous filtering options available to suit different budgets and needs. You can find small, affordable water filters that attach directly onto your kitchen faucet, providing filtered water on demand whenever you need it. Filtered pitchers are another popular option, offering a convenient way to keep filtered water ready for your plants in the refrigerator or on the countertop. For those seeking a more comprehensive solution, larger countertop or under-sink filtration systems are available that can handle greater volumes of water.

For maximum effectiveness, plant experts particularly recommend using a reverse osmosis water filter system. This type of filtration is considered the gold standard because it removes virtually all chemicals, minerals, and impurities from the water, leaving you with water that’s as pure as possible. While reverse osmosis systems represent a larger initial investment, they can be invaluable for serious plant collectors, especially those growing particularly sensitive or valuable specimens.

Why Tap Water Can Be Bad for Houseplants

If your home receives water from a public or municipal water source, as most urban and suburban homes do, the water may have some significant downsides when it comes to keeping your houseplants healthy and happy. Municipal tap water often contains chlorine, which is added to kill bacteria and make the water safe for human consumption, as well as fluoride, which is added in many municipalities to promote dental health. While these additives serve important purposes for human health, some plants react badly to one or both of these chemicals, developing visible symptoms that can affect their appearance and vitality.

Calatheas, popular houseplants prized for their striking patterned leaves, are particularly notorious for their sensitivity to fluoride. When watered regularly with fluoridated tap water, these plants will often develop brown edges along the leaf margins, brown tips at the ends of the leaves, and in some cases, may even develop brown veins running through the leaf tissue. This damage is not only unsightly but can also weaken the plant over time and make it more susceptible to other problems.

Calatheas aren’t the only sensitive plants to watch out for. Marantas, which are closely related to calatheas and share similar striking foliage patterns, exhibit the same sensitivity to tap water chemicals. Dracaenas, a popular group of houseplants that includes many varieties commonly found in homes and offices, can also show brown leaf tips and edges when exposed to fluoridated water. Spider plants, beloved for their ease of care and air-purifying qualities, are another species that commonly develops brown tips when watered with tap water containing fluoride and chlorine.

Given the wide variety of plants that can be sensitive to tap water, it’s important to take the time to research your specific plants and understand their individual water requirements and sensitivities. Some plants are quite tolerant and will do fine with tap water, while others will quickly show signs of distress. Knowing which category your plants fall into can help you make informed decisions about your watering routine.

If your tap water comes from a private well rather than a municipal source, the situation may be quite different. Well water typically lacks the chlorine and fluoride additives used in municipal treatment, making it generally more suitable for watering houseplants. However, there’s an important caveat to consider. Some private wells are treated with a water softener system to reduce the hardness of the water and prevent scale buildup in pipes and appliances. Water softeners work by replacing calcium and magnesium ions with sodium ions, and this softened water should never be used for plants. The salt content in softened water can be extremely harmful to plants, causing root damage, nutrient imbalances, and potentially killing your houseplants over time. If your home has a water softener, make sure to access water from a tap that bypasses the softening system, or use one of the alternative water sources discussed in this article.

How to Improve Tap Water

If you find that your home tap water isn’t ideal for your houseplants but you still need to use it for reasons of convenience, cost, or lack of alternatives, there are several practical steps you can take to improve its quality and make it safer for your plants.

The most straightforward solution is purchasing a water filter, as discussed earlier. Whether you choose a simple pitcher filter or a more sophisticated reverse osmosis system, filtration can remove or significantly reduce the chemicals and minerals that cause problems for sensitive plants. This investment can pay dividends in the form of healthier, more attractive plants that grow more vigorously and require less troubleshooting.

Another option that requires no special equipment is the sitting method. Simply fill a pot, bucket, or watering can with tap water and let it sit uncovered overnight, or ideally for 24 hours, before using it on your plants. During this time, chlorine, which is a volatile compound, will naturally escape into the air through a process called off-gassing. This method is free, easy, and can make tap water significantly better for your plants. However, it’s important to understand the limitations of this approach. While letting water sit will allow chlorine to dissipate, it does nothing to remove fluoride, which does not evaporate, or the dissolved minerals that can accumulate in soil over time. Therefore, this isn’t a perfect solution for particularly mineral-sensitive plants such as African violets, orchids, and calatheas, which may still develop problems even with dechlorinated tap water.

A more thorough option is to distill your tap water. Distillation is a purification process in which water is boiled until it turns into steam, causing the water molecules to return to a gaseous state. This steam is then collected and cooled, causing it to condense back into liquid water. During this process, virtually all impurities in the water, including minerals, chemicals, and other contaminants, are left behind and removed. The result is extremely pure water that’s ideal for sensitive houseplants.

Distilled water is indeed a good water source for your houseplants and will prevent the browning and damage caused by tap water chemicals. However, there’s an important trade-off to consider. Because distilled water is so pure, it lacks the nitrates, minerals, and nutrients that are naturally found in rainwater and even in tap water. While pure water won’t harm your plants, they do need these nutrients to grow and thrive. This means that when using distilled water exclusively, gardeners need to be more diligent about adding nutrients back into the soil manually through regular fertilization. A balanced houseplant fertilizer applied according to the manufacturer’s directions can help ensure your plants receive the nutrition they need.

You can distill water at home using special distillation equipment or even improvised methods, but it’s a time-consuming process that requires monitoring and produces relatively small quantities of water. For most people, purchasing distilled water from the grocery store is a more practical option. Distilled water is widely available and relatively inexpensive, typically costing around a dollar per gallon. However, if you have a large plant collection requiring significant volumes of water, the costs can add up over time, and you’ll also need to consider the storage space required to keep multiple gallons on hand. Additionally, regularly purchasing distilled water means more plastic bottles to recycle or dispose of, which may not align with everyone’s environmental goals.

Ultimately, the best water choice for your houseplants will depend on your specific situation, including the types of plants you grow, the quality of your local tap water, your budget, and your commitment to plant care. Many successful indoor gardeners use a combination of approaches, perhaps using rainwater when available, filtered water for their most sensitive plants, and treated tap water for their more tolerant species. By understanding the options available and the needs of your plants, you can develop a watering strategy that keeps your indoor garden flourishing.