Plants, no matter what type, require only the basic necessities to thrive. Sunlight in the right quantities, nutrients from the soil and water are all a plant needs to sustain itself. We spend a lot of time trying to decide what to feed our plants---and we should also consider the types of water. It's important to know what types are safe and what types are harmful.
Salt water is bad for your plants because it interferes with the absorption of water into the plants' roots. Salt will first build up around the plant's cells, blocking them from absorbing water. Later, the salt will actually work to pull water out of the plant as it settles in the soil. The salt content of ordinary tap water is too low to be a problem to plants.
Sugar water, too, is unhealthy for plants. While also pulling water out of the plant like salt water, sugar has an added effect. The sugar in the soil provides the right environment for bacterial growth. Bacteria growing in your plants' soil can cause plants to become unhealthy, and over time will kill them. Fungus can also grow the same way and have the same detrimental effects on plant growth.
Acidic water helps release metallic nutrients in the soil. These nutrients, such as zinc and copper, are beneficial to certain types of plants. Blueberries, roses, rhododendrons, and azaleas all do well in acidic water. Adding a little vinegar to your water will make it acidic; however, other plants will die if the water is too acidic.
Filtered water allows your plants to grow healthy and undergo photosynthesis properly. Water filtered by reverse osmosis or a similar process removes impurities such as chlorine, salt, acid and bases. Filtered water has only a positive effect on plants.
Well water has a nourishing effect on plants. Well water comes from deep below ground, and can carry with it nutrients from the soil that a plants needs. This will add to the soil as well in the same way fertilizer does. Well water leads to faster growing, greener, and healthier plants.