Before picking a removal method, you need to know which disinfectant your utility actually uses. There are two: free chlorine and chloramines (a combination of chlorine and ammonia). They behave differently, and several removal methods that work on free chlorine don’t work on chloramines at all.

Chlorine or Chloramines: How to Tell

Check your Consumer Confidence Report (CCR). Your water utility mails this annually, and most post it online. Search “[your city] water quality report” or “[your city] CCR.” Look for the section on disinfectants. It will state whether your utility uses chlorine or chloramines.

If you can’t find the report, call the utility and ask directly. It’s a simple question with a simple answer.

About half of US utilities have switched to chloramines as their primary disinfectant, including most large cities. Chloramines last longer in the distribution system and produce fewer disinfection byproducts, which is why utilities prefer them. But they’re harder to remove at home.

Method 1: Activated Carbon Filter

This works for both free chlorine and chloramines, with one important qualifier.

Standard activated carbon (the kind in most pitcher filters and basic under-sink cartridges) removes free chlorine effectively. For chloramines, you need catalytic carbon, which has a more reactive surface that breaks down the chloramine molecule rather than just adsorbing it.

A Brita pitcher uses standard activated carbon and is certified for chlorine (taste and odor) reduction under NSF 42. It’s not independently tested for chloramine removal. If your utility uses chloramines and you’re still tasting disinfectant through your Brita, that’s why.

Filters specifically marketed for chloramine removal, and filters that list NSF 42 chloramine certification, use catalytic carbon or extended-contact carbon designs. Those work.

For options, see the best pitcher water filters.

Method 2: Letting Water Sit Uncovered

This works for free chlorine only.

Free chlorine is a volatile gas dissolved in water. At room temperature, it off-gasses naturally. Leave a pitcher of water uncovered on the counter for 30-60 minutes and most free chlorine dissipates. In direct sunlight, it goes faster, sometimes within 15-20 minutes.

In the refrigerator with the lid on, off-gassing slows dramatically because it’s cold and covered. Don’t expect refrigerated water to dechlorinate itself overnight.

This method does nothing for chloramines. Chloramines are far more chemically stable and don’t off-gas meaningfully at room temperature. Leaving chloraminated water on the counter for 24 hours won’t resolve the taste.

If you’re on free chlorine, this is a zero-cost solution for drinking water. Fill a pitcher, leave it on the counter, drink from it a couple hours later.

Method 3: Boiling

This works for free chlorine only.

A rolling boil for 5 minutes rapidly drives free chlorine out of the water through evaporation. It’s effective but not practical as a daily method for drinking water.

Boiling concentrates dissolved minerals slightly (because water evaporates but minerals don’t). It doesn’t remove lead, PFAS, nitrates, arsenic, or any dissolved minerals. And it doesn’t work for chloramines.

There’s one situation where boiling dechlorination makes sense: before making baby formula when the alternative is untreated chlorinated water and you don’t have a filter. Even then, let the water cool before using it.

Method 4: Vitamin C (Ascorbic Acid)

This works for both free chlorine and chloramines.

Ascorbic acid (vitamin C) chemically neutralizes both disinfectants on contact. The reaction is fast. A 1,000 mg tablet of ascorbic acid will fully neutralize free chlorine in roughly 50 gallons of water.

You’ve probably seen this in fish tank products. Aquarium dechlorinators often use sodium thiosulfate for chlorine and ascorbic acid or a combined formula for chloramines.

Some shower filters use vitamin C cartridges specifically because they neutralize chloramines, which most other shower filter media don’t handle. Vitamin C shower filters are particularly popular for people with skin sensitivity to chloramines.

For drinking water, it’s not the typical approach, but it’s chemically sound and works well in applications like RV water tanks or camping setups where you’ve stored treated water and want to dechlorinate it before drinking.

Method 5: Sunlight and UV Exposure

This works for free chlorine only.

Direct UV light degrades free chlorine through photolysis. Leave water in a clear glass or container in direct sunlight for several hours and chlorine levels drop significantly. This is the same process that causes chlorine to dissipate faster in outdoor pools during summer.

It’s not practical for indoor daily drinking water, and it doesn’t work for chloramines.

Method 6: Reverse Osmosis

This works for both, though it’s overkill if chlorine removal is your only goal.

RO membranes require pre-filtration with activated carbon to protect the membrane from chlorine damage. That carbon pre-filter removes free chlorine and significantly reduces chloramines. The RO membrane itself then removes whatever the carbon stage misses.

If you’re installing RO for PFAS, lead, or nitrate removal and also want to address chlorine, the pre-filtration stage handles it automatically.

Cost Comparison

What to Do

Check your utility’s disinfectant first. If it’s free chlorine, a basic activated carbon pitcher is all you need. Brita, ZeroWater, and most pitcher brands work for this.

If it’s chloramines, look for a filter certified for chloramine reduction. That means catalytic carbon or a product with an NSF 42 chloramine listing. Standard carbon pitchers partially reduce chloramines but won’t eliminate the taste and smell the way they handle free chlorine.

For shower applications with chloramines, vitamin C cartridge filters or KDF-55 media are the most effective options. See the chloramines page for more on shower filter chloramine claims, and read the NSF certification guide to understand what the different certification levels actually cover.