Hydration Variations in Sourdough Starter: A Deep Dive

When diving into the world of sourdough baking, a term you’ll frequently encounter is “hydration.” In essence, hydration refers to the amount of water present in a mixture compared to the amount of flour. While it sounds straightforward, the hydration levels of a sourdough starter can significantly influence both the characteristics of the starter and the final baked product. Let’s explore this in more detail.

A regular sourdough starter has a hydration level of 100%, meaning equal weights of water and flour. A stiff sourdough starter, with a 60% hydration level, exhibits a vinegar-like sourness and a domed surface at peak maturity. In contrast, a liquid sourdough starter, at 125% hydration, presents a milder, yogurt-like sourness and displays numerous tiny bubbles on its surface when fully matured.

In sourdough baking, “hydration” refers to water-to-flour ratio by weight, expressed as a percentage. If you mix 100 grams of flour with 100 grams of water, you have a 100% hydration starter because the weight of the water is equal the weight of the flour; similarly if you mix 100 grams of flour with 75 grams of water, you have a 75% hydration starter.

1. Regular Sourdough Starter (100% hydration)

a. Characteristics 

A 100% hydration starter is the go-to for many bakers, especially those just beginning their sourdough journey. With equal parts of water and flour, it strikes a balance between consistency and activity.

b. Maintenance

Due to its pancake-batter-like consistency, it’s relatively easy to mix and feed. The balanced hydration level ensures a robust and active fermentation, making it forgiving for beginners.

c. Flavor Profile

This starter produces a balanced mix of lactic and acetic acids, resulting in a bread with a harmonious blend of tangy and mild sour notes.

2. Stiff Sourdough Starter (60% hydration)

a. Characteristics

As the name suggests, this starter has a denser, dough-like consistency. The reduced water content slows down fermentation, making it less vigorous than its 100% counterpart.

b. Maintenance

While it might require a bit more effort to mix due to its thickness, its slower fermentation rate can be advantageous, especially in warmer climates, as it offers a longer window for optimal ripeness.

c. Flavor Profile

The dominance of acetic acid in stiff starters gives the bread a pronounced sour bite, similar to that of vinegar. This sharpness can be a delight for those who crave a more assertive sourdough tang.

d. Ripeness Indicators

A mature stiff starter will exhibit a domed surface. As it reaches its peak activity, the center may start to sink, signaling that it’s time for a feeding or usage.

3. Liquid Sourdough Starter (125% hydration)

a. Characteristics

This starter has a more fluid consistency, almost like a thick soup. The increased water content accelerates fermentation, making it highly active and bubbly.

b. Maintenance

The runny nature of this starter makes it easy to stir and incorporate feedings. However, its rapid fermentation means it might require more frequent feedings, especially in warmer environments.

c. Flavor Profile

The liquid levain leans towards lactic acid production, which imparts a gentler, creamier sourness to the bread, akin to the tang of yogurt. This milder sour note can be perfect for those who prefer a less aggressive sourdough flavor.

d. Ripeness Indicators

A ripe liquid levain will showcase a plethora of tiny, soap-like bubbles on its surface. This effervescence is a clear sign of its readiness for bread-making.

Converting Stiff Starter to Liquid Starter and Vice Versa

By adjusting your starter’s hydration levels, you can influence its flavor profile.

As acetic acid production relies heavily on oxygen, to reduce the sharp vinegary taste in your bread, limit your starter’s oxygen absorption by adding more water. Over time, lactic acid-producing bacteria gradually become dominant, leading to a predominant mild sourness in the starter.

If you wish to change the hydration of your starter, do so gradually over several feedings to ensure the health of the starter is maintained. For instance, if moving from 100% to 75% hydration, reduce the water slightly with each feeding until you reach your desired level.


Hydration plays a pivotal role in sourdough baking, influencing everything from flavor to texture to fermentation speed. By understanding and experimenting with different hydration levels, bakers can tailor their sourdough products to their preferences, making each loaf a unique expression of their craft. As always, the key is observation, experimentation, and a touch of patience. Happy baking!


Hey there! I'm Sam, your go-to pal for all things sourdough. I've been baking and kneading for 10 fun-filled years, and I can't wait to share the joy of turning simple ingredients into heavenly sourdough bread with you. Grab your apron and let's dive into this amazing world of sourdough bread together on this blog.

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