The salt in the formula, the minerals in the water, and the use of dough conditioners or improvers affect the rate of fermentation. for a discussion of salt and its effect on fermentation.
Water that is excessively soft lacks the minerals that ensure proper gluten development and dough fermentation. On the other hand, water that is very hard—that is, has high mineral content and, as a result, is alkaline—also inhibits the development of the dough. These conditions are more of a problem for lean doughs than for rich doughs. In most localities, small bakeshops can overcome these problems with the proper use of salt or, in areas with alkaline water, by adding a very small amount of a mild acid to the water. Dough conditioners, buffers, and improvers that can correct these conditions are available from bakers’ suppliers. Their use should be determined by local water conditions.