Not everyone has time to bake sourdough bread once or twice a week and caring for a starter may sometimes be too much to handle because of a busy schedule. Then, in warmer months, a starter may become too active and produce more yeast than you need.
Instead of pouring your excess starter down the drain, freeze it. The yeast can survive being frozen.
Simply freeze one cup of starter in a freezer jar or sealing baggie. When it's needed, remove from freezer and allow to thaw in a bowl.