Watering your houseplants seems like a simple matter, but different types of water can have varying effects on plants. Tap water can be used for most plants unless water quality in a problem in your area. Bottled distilled water is used exclusively for certain types of plants that are sensitive to chemicals in tap water. You should monitor your plants' conditions to determine whether or not to change the water you use on your plants.
Advantages of Bottled Distilled Water
Distilled bottled water is sometimes recommended for houseplants when the build-up of salts that occur naturally in tap water causes problems with plant growth. Distilled water contains none of the salts or minerals found in common tap water. Water is boiled and the steam condenses into a purer form while leaving these compounds behind. Distilled water allows plants to take in moisture without absorbing additional minerals, leading to healthy roots and strong growth.
Disadvantages of Bottled Distilled Water
Bottled distilled water is more expensive than tap water. You must acquire a sufficient amount and carry it home periodically. Bottled distilled water must also be stored, which makes it less convenient for those who live in apartments or other small spaces.
Advantages of Tap Water
Tap water is cheap and always available. There is no need for storage capability, and it is generally free of contaminants such as fungus and bacteria. Though tap water often contains small amounts of chlorine for decontamination, it is not a sufficient amount to injure most plants. Tap water may also contain small amounts of fluorine added to help prevent tooth decay. Washington State University Extension recommends not using tap water for sensitive plants such as spider plants, corn plants and palms.
Disadvantages of Tap Water
Tap water contains calcium and magnesium, which can build up on the soil surface causing a white powdery film. These concentrated salts can cause dehydration of the root structures. Excess salts cause plants problems such as inhibited growth, small new growth, dead roots and wilting of leaves, according to Ohio State University Extension. Gardeners must periodically remove these built-up salts by leaching the soil with a large amount of water to remove the salts. You can also remove the plant from the pot and replace the soil. Tap water can also contain nitrates from fertilizer run-off. This will contribute to excess nitrogen in the soil, creating an imbalance in nutrients.