Chloramine

At a glance: Chloramine is a long-lasting disinfectant that many US utilities use instead of chlorine, and it is safe to drink at the levels they use, with the same 4 mg/L EPA cap. It is harder to filter than chlorine. If you want it out, choose catalytic carbon or a filter that lists an NSF/ANSI 42 chloramine claim, because a plain chlorine claim does not cover it.

EPA says more than one in five Americans drinks water treated with chloramines, so if you are on city water there is a fair chance you have it.

What it is and where it comes from

Chloramines form when a utility adds ammonia to chlorine. The common form in drinking water is monochloramine. EPA says utilities have used chloramines since the 1930s, and some switched to them to meet disinfection byproduct limits.

The CDC explains the trade-off. Chloramine lasts longer in the pipes than chlorine, which helps utilities with long distribution systems keep water disinfected to the last tap, and it forms fewer disinfection byproducts. The downside for homeowners is that the same stability makes it harder to remove.

Private wells do not have chloramine. It is only added by public water systems.

Health and household effects

For people drinking it, chloramine at utility levels is not a health concern. EPA says chloraminated water that meets its standards is safe for drinking, cooking and bathing, and the CDC says levels up to 4 mg/L are considered safe. Above EPA’s cap, EPA lists eye and nose irritation, stomach discomfort and anemia as possible effects.

Three situations need special care:

• Fish, reptiles and amphibians. Chloramine harms them, and the CDC notes that letting water sit removes chlorine but not chloramine. Use a tank conditioner labeled for chloramine.
• Home dialysis. EPA says dialysis patients can drink chloraminated water, but the water used in the dialysis machine must have chloramine removed because it contacts the blood.
• Utility switches. Some utilities that use chloramine switch to chlorine for a few weeks to clear biofilm from pipes, according to the CDC. Taste and smell can change while they do.

Limits and what they mean

Standard	Level	What it is
EPA maximum residual disinfectant level	4 mg/L (as Cl2)	Enforceable cap for public water systems
EPA health goal (MRDLG)	4 mg/L	Level with no expected health risk
WHO guideline for monochloramine	3 mg/L	Health-based international guideline

EPA measures chloramine “as Cl2,” the same way it measures chlorine, so the numbers on your utility report are directly comparable.

How to test

1. Read your Consumer Confidence Report. The disinfectant section names chlorine or chloramine and gives the range measured. It is free, and your utility must publish it every year.
2. Use a DPD test kit. Buy one that reads both free and total chlorine. Total minus free is combined chlorine, which is the chloramine. If most of the total is combined, your utility uses chloramine.
3. Test after a filter. The same kit shows whether a filter is removing chloramine. Test total chlorine before and after it.

Treatment options

The key number is contact time. Robert Potwora’s analysis in Water Conditioning & Purification found monochloramine needs at least two to four times the contact time of free chlorine, and recommends at least 10 minutes of empty bed contact time with ordinary granular carbon. Catalytic carbon cuts that to about 3 minutes.

Method	How well it works	Certification to look for	Cost range
Catalytic carbon, whole house	High when the tank is sized for contact time	NSF/ANSI 42, chloramine reduction	$1,160 to $1,400 (systems we track)
Carbon filter with a chloramine claim, point of use	High	NSF/ANSI 42, chloramine reduction	$10 to $100
Standard activated carbon, whole house	Low to moderate at full flow	NSF/ANSI 42 (confirm chloramine is listed)	$500 to $3,000
Reverse osmosis	Moderate to high, depends on carbon stages	NSF/ANSI 42 chloramine claim plus NSF/ANSI 58	$300 to $1,500

Cost ranges are Minnesota Department of Health estimates based on 2017 and 2018 quotes, low end self-installed and high end professionally installed, unless the row says “systems we track,” which are prices checked September 2026.

Check the certification carefully. NSF/ANSI 42 has a separate claim for chloramine. A product certified for chlorine has not shown it handles chloramine. None of the whole-house chloramine filters we track holds an NSF/ANSI 42 certification for chloramine, so for those you are relying on the maker’s claim and the carbon type. The filter finder shows each product’s actual claims.

Size for your flow. A whole-house tank sized at the edge of your peak flow gives water less contact time than chloramine needs. Our sizing guide shows the contact time arithmetic, and the chloramine vs chlorine guide works through an example.

You may not need a whole-house system. If the goal is better-tasting drinking water, a point-of-use filter with a chloramine claim is far cheaper. See whole-house filter vs reverse osmosis and our city water picks. While you have your utility report open, look up your system on the PFAS lookup too.

When to call a professional

Use a licensed plumber for whole-house carbon tanks, which go on your main line and need a bypass valve.

If you do home dialysis, talk to your care team and dialysis technician before changing anything, and tell them if your utility announces a switch between chlorine and chloramine.

Call your utility if total chlorine on your test kit is well above the range in its annual report, or if taste and smell change suddenly. It can tell you whether it has changed treatment.