Water Comparison Test for Bread Making
Some baking books and experts claim that bread rises and tastes better when dough is made using high-quality water—which usually means filtered, distilled, or deionized water that contains very few dissolved solids. We put this idea to the test by making the same recipe for a poolish starter with five different kinds of water: ordinary tap water (the default source of water for nearly all bakers), store-bought distilled water, commercially filtered water, hard mineral water having a total dissolved solids concentration of 475 parts per million (ppm), and deionized water that we had chlorinated to a pool-like pH of 8.9 (or 1 ppm).
We set up a comparison test by first mixing 100 g / 3.5 oz of tap water with 100 g / 3.5 oz of flour and 0.2 g / .01 oz of our instant yeast. We then covered the container tightly with a balloon to trap the gas produced by fermentation and left the starter to sit at 21 °C / 70 °F for 12 hours. We did the same for four other starters made using the remaining types of water.
The results of the experiment are shown in this video that was shot over about 16 hours of fermentation. Despite differences in fermentation speed, all five variants did ripen sufficiently to use in a dough. We took these tests a step further by baking French lean breads and sourdoughs with these different waters. There was almost no difference in the final loaves in terms of taste and size.