Many aquarists ask whether it is acceptable to use tap water for their reef aquaria. The answer obviously depends on what is in their tap water. We have all heard of aquarists who use only tap water and are seemingly very successful. We’ve also heard the opposite, such as folks that had significant problems until they purified their water. How is an aquarist to decide what to do?
Aside from the standard concerns about chlorine and chloramine,1 there are a variety of chemicals to be concerned with. One source for information on these chemicals is the annual water quality report from your municipal water supply, if on a public system. If you have a private well, you may need to get a test of your own water to know if it is suitable.