Yes** but chlorine/chloramines are only part of the issue. Your water is guaranteed to contain a mix of minerals that includes copper, which is fatal to invertebrates such as snails and corals. Those minerals do not evaporate, so the concentrations in your tank will gradually increase when topping off with fresh water and eventually reach hazardous levels. RODI prevents this issue from occurring. In a pinch, you are probably fine to use it since tap concentrations are very unlikely to be hazardous. Long term, you want to use DI water.