The Enemy Within Tap Water: Chlorine and Chloramine.

Municipal water supplies are treated with disinfectants to make them safe to drink. The most common are chlorine and chloramine (a more stable compound of chlorine and ammonia).
These are biocides. Their entire purpose is to kill or inhibit microorganisms. Your
sourdough starter and the yeast in your dough are the beneficial microorganisms you want to thrive. Chlorine can weaken or kill commercial yeast and sourdough starter, leading to slower, less vigorous rises.

The Impact of Water Hardness (Calcium)

Hard water contains high levels of dissolved minerals, primarily calcium and magnesium. In moderation, these minerals are actually beneficial. When water is too hard, it can overtighten the gluten, making the dough stiff and less extensible. This can result in a loaf with a dense crumb and a limited oven spring. Very high mineral content can also slow down fermentation. Conversely, very soft water (low in minerals) can produce dough that is slack, sticky, and difficult to shape because the gluten lacks the structural support from the calcium.

The Role of pH

The optimal pH for yeast activity and enzyme function is slightly acidic, ideally between 5.5 and 6.0. Tap water can often be alkaline (pH above 7) to prevent pipe corrosion. Alkaline water neutralizes the natural acidity of the dough. This can slow down the work of enzymes that break down starches into sugars for the yeast to eat. The result can be bland-tasting bread with poor color.

Spring Water vs. Filtered Water

It’s a great, consistent choice because its mineral content is naturally balanced and listed on the bottle. It’s free of chlorine and has a predictable, usually slightly acidic pH. You know exactly what you’re getting, which removes a major variable from your baking.
• Distilled Water: You should generally avoid distilled water. It is too “hungry” for
minerals and can actually leach them from the dough, weakening the gluten
structure.
• Filtered Water: this is the baker’s choice. A good carbon filter removes chlorine/
chloramine and some sediment, but it may not significantly alter the mineral content (hardness). For total control, some serious hobbyists and bakeries use reverse osmosis (RO) systems, which strip the water of everything, and then they readd specific minerals in precise amounts to create their “perfect” baking water.
Here’s a breakdown of why water is so crucial, from the moment you mix the dough to the moment you take the bread out of the oven.

1. It’s Essential for Hydration and Gluten Development
Water is absorbed by the starch granules and proteins in the flour. This hydration is what transforms dry flour into a pliable dough. The two key proteins in wheat flour, glutenin and gliadin, need water to link together and form gluten. Think of gluten as a network of tiny, elastic strands. Water allows these strands to form, creating a stretchy matrix that can trap the gases produced during fermentation. Without enough water, this network cannot form,
and you’ll end up with a dense, crumbly dough instead of an elastic one.

2. It Creates the Perfect Environment for Yeast Activity
Water dissolves the sugar and minerals in the flour, creating a food source that the yeast can consume. The yeast cells need a moist environment to move around and come into contact with their food. As yeast consumes sugars, it produces carbon dioxide (which makes the bread rise) and water. The dough’s hydration level is a dynamic balance influenced by the yeast itself.

3. It Controls the Dough’s Temperature
Water is your primary tool for managing the dough’s temperature, which directly impacts fermentation speed. A consistent dough temperature, achieved by controlling the water temperature, leads to predictable and repeatable results. Click here to learn more.

4. It’s Key for Starch Gelatinization and Crust Formation
This happens in the oven and is the final, transformative role of water. As the inside of the bread (the crumb) heats up, the starch granules absorb the available water and swell, a process called gelatinization. This sets the final structure of the crumb, turning it from a sticky batter into a light, solid, but soft sponge. On the outside, the high heat causes the water to evaporate rapidly. However, if there is extra moisture (like steam injected into a commercial oven or created by a pan of water in a home oven), it keeps the crust soft and flexible for the first few minutes of baking. This allows the loaf to achieve its maximum “oven spring” (its final rise) before the crust hardens and browns. The browning itself (the Maillard reaction and caramelization) also requires heat and occurs best in the presence of moisture.

5. It Impacts Texture, Flavor, and Shelf Life
The amount of water, known as hydration, is a defining characteristic of a bread recipe. It may vary from 60 to 90 percent. More water (a higher hydration dough) generally leads to a more open crumb with larger, irregular holes and a chewier texture (like a ciabatta or focaccia). Less water leads to a tighter, finer crumb and a softer, more pillowy texture (like a standard sandwich loaf). A good compromise is around 70%. Higher hydration doughs often ferment faster and can produce more complex, tangy flavors because the moisture makes the environment more active for enzymatic processes. Bread stales because it loses moisture. A bread that starts with good hydration will stay softer and fresher for longer. The water locked into the gelatinized starches is what keeps the crumb tender.