The mikvah building has a pool for ablutions, as prescribed by Jewish law. A woman must take a dip in the mikvah after the end of her monthly menstrual cycle in order to maintain marital purity. Therefore, the mikvah is considered the basis of Jewish family life and even more important than the synagogue. According to Jewish law, only "living" water - ie. water of natural origin - can bring spiritual purification, but in practice a dip in a river or lake is not always possible. So a mikvah is built to imitate natural water. The mikvah contains a pool in which women bathe which contains a mixture of tap water and water from a small reservoir filled with natural rainwater. The rainwater and tap water come into contact, making the water "alive".