Has your sourdough starter become thin, watery or difficult to stir?
Don't worry—this is a common question, especially if you're new to sourdough or activating a dehydrated starter.
In most cases, a runny starter isn't a sign that anything has gone wrong. It simply means it's time to look at your feeding routine and hydration.
The short answer
A runny sourdough starter is usually caused by one of three things:
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it's hungry and has broken down after using up its food
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it has been fed with too much water
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it's fermenting quickly in a warm environment
Most runny starters recover easily with a consistent feeding routine.
Why has my starter become runny?
As your starter ferments, the wild yeast and bacteria consume the flour you've fed them.
Over time, they begin to break down the structure of the mixture, making it thinner than it was when you first fed it.
This is completely normal and often happens when your starter is ready for its next feed.
If your kitchen is warm, this process can happen even faster.
Check your feeding ratio
One of the most common reasons for a runny starter is adding too much water when feeding.
If you're feeding by weight, a 1:1:1 ratio (starter, water and flour) creates a starter that's easy to mix and suitable for most beginners.
If you're measuring by cups or spoons instead of scales, it's easy to accidentally add more water than intended because flour and water don't measure equally by volume.
Using kitchen scales gives you much more consistent results.
Can I make my starter thicker?
Yes.
If your starter has become quite runny, you can simply reduce the amount of water slightly at your next feed or increase the amount of flour.
Many bakers also give their starter a slightly thicker feed if they're trying to slow fermentation or fit it around their schedule.
The goal isn't to make it as thick as possible—it's to find a consistency that works well for your routine.
Does flour make a difference?
Yes.
Different flours absorb different amounts of water.
Wholemeal and rye flours generally absorb more water than white flour, so your starter may naturally feel a little thicker when using them.
If you've recently changed flour, it's normal to notice a change in consistency.
When should you worry?
A runny starter on its own isn't a problem.
However, if your starter is also showing signs of mould, unusual colours or a rotten smell, it's safest to discard it and start again.
Otherwise, a thin starter is usually something that can be corrected with your next few feeds.
Nikki's note
One of the biggest mistakes I see is people trying to "fix" a runny starter by making lots of changes at once.
Keep it simple.
Feed it consistently, use accurate measurements and give it time to respond.
Your starter is always giving you information—you just need to learn how to read it.