When the water is too cold, it chills the roots of African Violets, causing leaves to curl down as the water is absorbed into the plant. Also, if watering from the top, cold water can cause leaf spotting. Such spots represent a form of necrosis and, as such, cannot be removed. The only exception to this is when you are spray misting for purposes of quick-feeding or increasing the humidity around your plants. Never use soft water.
Soft water increases the saline content.
This will alter both the pH and the electrical conductivity of the soil, thereby diminishing your African Violet's ability to absorb water and nutrients. If you have soft water, you may be able to divert water before it reaches the softening unit. If not, you will need to seek an alternative source of water. Avoid using highly chlorinated water. While some chlorine is actually necessary for photosynthesis to occur, African Violets need very little, i.e., 70-100 ppm.