US cities disinfect tap water with one of two things: chlorine or chloramine (chlorine combined with ammonia). According to the EPA, more than one in five Americans use water treated with chloramines. Both keep drinking water safe. The difference matters mainly if you're thinking about a shower filter.
Why the difference matters
Chloramine is more stable than chlorine. That's why utilities use it: it lasts longer in the pipes and forms fewer disinfection byproducts. The same stability makes it harder to remove in the split second water spends passing through a shower head. Filters that do well against free chlorine may do noticeably less against chloramine, and research on popular media like vitamin C against chloramine is mixed.
So before buying any shower filter, it helps to know which one you have.
Find out in two minutes
- Find your water utility's annual report. Every US community water system has to publish a water quality report each year by July 1. EPA's CCR page explains how to find yours, or search your water company's name plus "water quality report."
- Search the report for "chloramine" or "monochloramine." If it's listed under disinfectants, your water is chloraminated. If the disinfectant row just says "chlorine" or "chlorine residual," you have free chlorine.
- Check which system you're on. Big utilities run several systems, and they don't all use the same disinfectant. In New Jersey, for example, New Jersey American Water uses chloramine in some systems and chlorine in others. Match your town to the right report.
Or test it yourself
Many chlorine test strips have two pads:
- Free chlorine: the chlorine that's ready to react. This is what a shower filter removes most easily.
- Total chlorine: free chlorine plus chloramine.
If total chlorine reads much higher than free chlorine, your water is probably chloraminated.
What we're doing about it
Rinseproof is a filtered shower head that ships with test strips, so you can check your own water before and after. We're testing ours on both chlorine and chloramine water and will publish the results, including if chloramine results are weak. Join the launch list to see them.