Hi everyone,

I was wondering for those of you using a RODI system and are on Ann Arbor city water or using another city's water, if you know if the city uses chlorine or chloramines for water disinfection. I am in the process of moving from AA to Minneapolis (my tank is already in MN actually), and because I was in the process of buying a RODI system, I investigated whether Minneapolis city water contained chlorine or chloramines. After a couple calls to the Minneapolis water department it was evident that chloramines were used, although chlorine is added to the water in the process of generating chloramines (so the water contains both free chlorine and conjugated chlorine in the form of chloramines).

Well, I had also asked this question to a Twin City reef club, and to my surprise, most respondents did not know which the city used, and worse, others were confident it was chlorine, not chloramines. It is important to know which is in the city water if you purify your own water as chloramines require special filters and/or special/extra DI resin for removal. In Minneapolis, as in AA, the water department provides an annual report to citizens on city water quality. The Minneapolis reports, which were available online, were a bit confusing because the recent reports made no mention of chloramines, but did list chlorine as being in the water. So the TC club interpreted in the report the presence of chlorine as proof that chlorine, not chloramine, was used for disinfection. However, as stated above, the water contained both chlorine and chloramines. Not even a staff member at BRS, which is located in Minneapolis, was confident which disinfectant was used in the city water. This was a surprise as BRS sells special RODI systems for chloramine removal.

I have not investigated AA city water because I am leaving town. But I am curious how many of you know what is in your city water, chloramines or chlorine only. The staff member at the Minneapolis water department with whom I communicated said that more and more cities are switching to chloramines.

So my question is do you know if your city uses chlorine or chloramines for water disinfection?

Adam