It's best to use filtered or distilled water when misting your houseplants. If you mist a lot, tap water can cause mineral build-up on your plant leaves.
For most people and most plants, regular tap water is just fine. The exception would be if you have some particular plants, such as any carnivorous plants, some orchids, possibly some calatheas, etc.
You only need distilled/rain water for watering. Tap in a humidifier will not at all negatively affect the plant.
Tips for Misting
To mitigate this, be sure to use rainwater or distilled water when you mist your plants. Avoid filtered water, as the salts in many water filters can be damaging to plant roots and leaves. It's also important to regularly dust and clean your leaves.
If you feel that your water is damaging to your plants, you can use bottled water, not distilled, but the kind that comes from underground springs. Or you can use rain water, especially when it has run off of trees. More important than the source of water is that you use enough of it.
One common substitute for distilled water is purified water, which has undergone a filtration process to remove impurities. While purified water may still contain some minerals, it is generally considered a safe alternative in most cases, especially for cleaning or drinking.
Boiled water refers to water that's simply been heated to boiling point. Although this kills potential pathogens that can be harmful to humans, it's not considered purified. Distilled water, however, is a much purer form of water that's had all of its impurities, minerals, and microorganisms removed.
It's best to use filtered or distilled water when misting your houseplants. If you mist a lot, tap water can cause mineral build-up on your plant leaves.
Cacti, succulents, fiddle leaf fig (Ficus Lyrata), and other plants that prefer dry environments are among them. Although they prefer humidity, watering fuzzy-leaved plants like African violets and piggyback plants (Tolmiea menziesii) is not recommended since the water droplets will mark the surface of the leaves.
Misting often, especially during the dry winter months, will help create good humidity around indoor plants. Some plants can easily be misted three times a week. However, misting may not always be useful for indoor plants because the water can evaporate into the air if the weather is very dry.
Most importantly, minerals in tap water may increase the development of crusty deposits, or scale, in humidifiers. Scale can be a breeding ground for microorganisms. Retarding the growth of scale is the most compelling reason to find alternatives to tap water.
Turn on your stove's burner to medium heat and let the water boil. Then place the lid upside-down over the pot and fill the top with ice. This will create condensation as the steam from the boiling water hits the ice-cold lid. The condensation will begin to drip into the bowl, leaving you with distilled water.
If the air in your house is dry, such as during the winter months, your plants may benefit from the use of a humidifier. Compared to misting or using a pebble tray, a humidifier will provide a more constant humidity level for your tropical houseplants.
If you use tap water, you may notice that your plants are not growing as tall and strong to the best of their abilities. To reduce the risk of harmful chemicals in your water, allow your tap water to sit out for at least 24 hours before using it to water your plants. This allows the chlorine to dissipate.
Plants with long, narrow foliage such as Spider Plant, Peace Lily, Dracaena, and Prayer Plant can be negatively affected by tap water high in fluoride. Plants also prefer their water at a pH level between 5.0 and 7.0.
Best Water for Indoor Plants
Most tap water should be fine for houseplants unless it's softened. Softened water contains salts that can build up in the soil over time and cause problems. Chlorinated water is also safe for most houseplants, but, if possible, water from a filtration system is much better for your plants.
Misting can provide several benefits for certain types of indoor plants. For one, it can help increase the humidity level around your plant which can be beneficial for those that thrive in humid conditions. This is particularly useful during winter months when indoor air tends to be drier due to heating systems.
“Plants like cacti or succulents thrive in dry climates, so a humidifier is not necessary and could be detrimental to the plant,” adds Root.
The Cons of Plant Misting You Should Know
In a poorly ventilated space, water droplets on the leaves create a perfect breeding ground for fungi. Also, irregular misting could lead to inconsistent humidity levels, which may stress the plant.
While using water straight from the tap might seem good enough for your plants, by now we know it's highly advisable to put your water through a filtration system before watering your plants. Filtered water is not only good for you, but it's great for your plants too.
While convenient, tap water contains minerals that can cause buildup on your humidifier. On the other hand, distilled water is free from these minerals and contaminants, making it the best option for humidifiers.
Do not mist plants with fuzzy leaves, like African violets and piggyback plants (Tolmiea) – water on their leaves will lead to permanent spotting. Here you can use a humidity tray. Fill a tray, plate, or bowl with pebbles, river stones, et cetera and fill with water just below the top.
Filtered water is one solution. Filtered water starts out as plain tap water. You may already have filtered water in your home by way of a whole-house filtration system, a faucet filter or a water filtration pitcher (you can even get a filtered water bottle).
With both boiling and chilled water being unsuitable for a humidifier, the most effective and least damaging temperature to choose is room temperature.
As far as distilled, you would need a pot to boil water with a bowl over the top, suspended somehow that is wide than the pot with boiling water, then you would need an even bigger pot to surround the bowl and small pot to capture the water that gets boiled off and drips down the sides of the bowl for distilled water.