Sourdough Starter Not Rising After 4 or 5 Days — Causes & Fixes
It's almost always temperature or chlorinated water — both kill wild yeast before it can establish.
Your brand-new starter sat for four or five days and still hasn't bubbled or risen. The mix smells faintly sour or like nothing at all, and you're starting to worry you've killed it.
What it looks like
- No visible bubbles on the surface or sides of the jar
- No rise between feedings, or rise so small it's hard to measure
- Mild yeasty or wet-flour smell, neither pleasant nor offensive
- Mixture looks slightly translucent or watery on top
Why this happens
Kitchen is too cold
Wild yeast multiplies fastest between 75–80°F. Below 70°F, growth slows dramatically. Below 65°F, it can stall entirely in a brand-new starter that doesn't yet have a thriving population.
Chlorinated tap water
Municipal water is chlorinated specifically to kill microbes. The same chemistry that makes tap water safe to drink makes it hostile to building a starter.
Wrong flour
Plain bleached all-purpose flour has fewer wild microbes and slower fermentable starches than whole rye or whole wheat. A new starter on bleached white flour can take twice as long.
Too much discard, too soon
If you started discarding before the bacteria/yeast population stabilized (typically day 3 or 4), you may have thinned the culture below sustainability.
How to fix it
Move it somewhere warmer
On top of the fridge, near a south-facing window (out of direct sun), or inside the oven with just the interior light on (creates a stable 78–82°F box). A heating pad on its lowest setting under a tea towel works too.
Switch to filtered or bottled water
Use spring water, filtered tap, or tap water that has sat uncovered for 12+ hours so the chlorine evaporates. The result is dramatic in a day or two.
Add a tablespoon of whole rye
Whole rye is the highest in wild yeasts and amylase enzymes (which produce fermentable sugars). One tablespoon mixed into the next feeding can jump-start a stalled jar.
Give it three more days
Don't give up at day 5. Stalled starters often pop on day 7 or 8 once temperature and water are corrected. Stir vigorously twice a day to keep oxygen in.
Preventing it next time
- Pick the warmest spot in your kitchen before you start.
- Use filtered water from day one.
- Start with whole rye or whole wheat, even if you plan to switch to bread flour later.
- Wait until day 4 to discard for the first time.
Most starter problems show up in the data.
Sarah's Sourdough — the iOS app — logs every feeding, photographs every rise, and predicts peak by your kitchen temperature. Problems become visible weeks earlier.
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Related problems
Smells like nail polish remover
Your starter is starving. Acetone is what active yeast produces when it's eaten everything in the jar and started consuming itself.
Sluggish in winter
Sourdough fermentation roughly doubles in speed for every 18°F rise in temperature. A 68°F winter kitchen ferments at roughly half the speed of an 80°F summer kitchen.