“Tap water will kill your starter”

For an established starter, tap water is almost always fine.

Why

Chlorine in drinking water is there in tiny amounts, and a healthy starter is a dense, fast-growing population that shrugs it off. Where water can matter is at the very beginning, when a new starter is only a few fragile days old, or in places with unusually heavily treated water.

Further down

Plain chlorine leaves water that stands uncovered for a few hours. Chloramine, which many suppliers use instead, does not, and boiling doesn't remove it either. If a starter is struggling for no other reason, filtered or bottled water for a week is a cheap experiment. If it's healthy, there is nothing to fix.

Words used here Starter

Updated 7 October 2026