To Bake Your Bread Better, Use Filtered Water
Baking beautiful bread requires skillful manipulation of three complex factors: technique, equipment and ingredients. Poor technique is responsible for most poor results, but a sudden change in kitchen conditions or the availability of ingredients can confuse even a seasoned baker. If your bread starts to go bad for no reason, it may be because of the water.
Tap water has two qualities that can make it difficult to make leavened bread: chlorine content and hardness. Chlorine-containing compounds, particularly monochloramine , are used in water purification because they kill dangerous microorganisms at extremely low potable concentrations, but that means they can also kill yeast. In terms of mineral content, excessively hard water (in which the level of dissolved minerals is increased) prevents a good rise due to its increased alkalinity. Our little yeast friends thrive in slightly acidic conditions, so forcing them to develop in highly alkaline environments is counterproductive at best.
The vast majority of drinking tap water does not contain enough chlorine or minerals to interfere with baking; generally speaking, yeast bread is good for all but the most extreme water conditions. However, in my experience, naturally leavened doughs – especially leavened doughs – can be quite sensitive to water changes. I suspect this is due to differences in the metabolism of the leavening agents. Instant (or active dry) yeast is quite strong and can be added to dough in large quantities to help it rise quickly under various dough conditions. Wild yeast and lactobacilli in the sourdough act much more slowly, which requires longer exposure to various chemical compounds dissolved in tap water and increases the likelihood of an unwanted reaction.
Homemade baking forums are filled with threads about water quality; some people even selectively remineralize distilled water to precisely control the chemistry of their starter cultures. Honestly, this is some new level of control shit: all other things being equal, if your tap water is drinkable, that’s probably okay. However, if your water is highly chlorinated, very hard, or very sulfurous, try filtering it out before adding it to the bread dough. Philadelphia tap water (sorry, “forest”) is quite chlorine, and the switch to filtered water completely changed the rules of the game: our sourdough is no longer ahead of schedule, the sourdough loaves are fully fermented without unexplained decay halfway through. rises, and the yeast dough rises high and airy.
Filtered water cannot magically fix under-kneading orover-proofing of bread, so make sure your technique is correct before blaming water for poor baking. But if your tap water is unpleasant to drink or harsh enough to require regular descaling, a filter may be just what you need to start making great loaves of your own.