Watering plants with distilled water avoids contaminating the soil with any minerals or chemicals that would be found in tap water. According to professorshouse.com, water that has not been distilled contains minerals; in fact minerals are what give water a taste. Many water distribution systems add chemicals to kill any microbes in the water. Minerals and chemicals in water are more of a problem for house plants than outdoor plants where occasional rains will wash those substances out of the soil.

On the Other: Chlorine Can be a Problem

According to the U.S. Department of Energy there is evidence that chlorine causes chloridosis or yellowing of the leaves. They suggest letting the water set for several days or treat the water with a dechlorinator, a substance available at a pet fish supply store, to remove the chlorine.

Bottom Line

Plants watered with distilled water will likely do better than plants watered with tap water although removing the chlorine will reduce the yellowing caused by tap water from a water distribution system. Water drawn directly from wells and not chemically treated often contain minerals that may also cause problems for plants.

Source:

Professor's House

Department of Energy