Tap water can be troublesome to your starter. City water contains chlorine and other chemicals. These chemicals are added to city water to kill unwanted bacteria. What makes great sourdough bread are wild yeasts and good bacteria that are all around them in the air. The last thing we want to do is kill that good bacteria with the chemicals in tap water. Luckily, it’s easy to prepare tap water for sourdough baking or feeding. Simply boil it and let it sit on your counter for a few hours. This allows the chemicals to evaporate. You can make a big batch of water and keep it in a special pitcher so you do not have to do this step each time you feed your starter or bake bread.