Should I Be Concerned About the Chlorine in My Drinking Water?

Gina Solomon responds:

Chlorine itself is somewhat irritating to the skin and mucus membranes, so people with sensitive skin can have problems when they shower in chlorinated water. The real problem with chlorine, however, is that it chemically reacts with other organic material in the water to create disinfection byproducts known as "trihalomethanes" or "THMs". The most familiar THM is chloroform, but there are many others that also occur. THMs have been linked to bladder cancer and to reproductive disorders including miscarriage. Worse still, they are volatile and therefore can be inhaled in the shower or even when washing dishes. The EPA has taken some action in recent years, by reducing allowable amounts of THMs in drinking water. In response, many water systems have switched to chloramine (which is basically bleach), and some forward-thinking systems have moved to ultraviolet light disinfection pre-treatment. Chloramine is a concern as well, not only because it will kill your pet fish, but because it creates a variety of disinfection products that seem to be as bad as--or worse than--the THMs.  
 
The good news about these disinfection byproducts is that they are readily removed by most carbon filters, including countertop filters such as the Brita. Since these chemicals are volatile, they are even removed by just letting the water stand in a pitcher in the fridge or on the counter for a little while before drinking it. Boiling water (for tea or coffee) also eliminates these chemicals.  
 
If you are on a municipal water supply, a simple step is to request that they give you their "Consumer Confidence Report", which should include their testing results. This should come at least annually in your water bill anyway, and it's also usually on the utility's website. The legal maximum for the THMs is 80 ppb, and the maximum for other disinfection byproducts known as haloacetic acids (HAA5) is 60 ppb. Ideally the numbers should be considerably lower than these. If the numbers are even close to these levels, you might want to consider using a carbon filter or filter pitcher.