Many researchers have attempted to answer the question; is tap water safe for bathing and showering. Results have varied over the years, but the general consensus is that taking a shower in chlorinated water increases an individual’s lifetime risk of bladder and colorectal cancer due to THM exposure.Studies began in 1984. The concern was that the EPA had not included exposure to airborne chloroform (a THM), which at that time was only considered a “suspected” human carcinogen, in their risk-assessment calculations.Chloroform and other THMs are byproducts released when chlorine and other chemical disinfectants interact with bacteria and other living things in public water sources. In 1984, they could not answer the question; is tap water safe for bathing and showering. They could only suggest that further study was needed.Over the years, 11 more studies have been conducted in an effort to advise the public about their risk and the efforts they should and could make to protect themselves. The results of the studies were not always in agreement, but researchers did agree that there was a risk.In 1999, they said the primary risk was from ingestion; drinking. In 2000, they concluded that inhalation exposure from cooking and showering was equivalent to ingestion, thus carried an equivalent risk. Later in 2000, another study found that blood levels were “higher” after a 10 minute shower than they were after drinking a liter of chlorinated water.Again in 2000, they tried to answer a slightly different question. Is tap water safe for bathing and showering, when it comes to the build-up of chloroform gas and other THMs in the air of the bathroom and the rest of the house?You see, they know that inhalation of these gases is a problem. The gases are considered a work-place hazard in industrial settings where they exist. You can’t smell these gases. You can often smell chlorine, but not THMs.What researchers found is that there is a measurable level of chloroform gas in homes without a good air exchange rate. In other words, if you are not going to invest in a showerhead filter that removes THMs, leave your windows open.In 2007, the results of a three year long well-controlled case study were published. These researchers gave a more definitive answer to the question; is tap water safe for bathing and showering. Multiple areas of exposure were considered, including swimming in chlorinated water.They concluded that due to multiple exposures over the course of one’s lifetime, you are twice as likely to develop bladder cancer if your home has chlorinated water. They also concluded that the highest rate of exposure was in the shower.You can easily and inexpensively protect yourself with a good showerhead filter, but shop carefully. Most of them only reduce chlorine and do nothing about THMs.So, what do you think? Is tap water safe for bathing and showering, when you do not have an effective showerhead filter? I would have to say, No!