The question of whether showering in chlorinated water is safe is a common concern for people who understand that chemicals are added to their municipal water supply. Chlorine is introduced into public water systems because it is a powerful disinfectant, successfully eliminating disease-causing bacteria and pathogens like those responsible for cholera and typhoid fever. This process is a public health achievement, ensuring that tap water is safe to drink. While the water is safe to ingest, the unique environment of a hot shower—with its heat, spray, and duration—creates conditions that change how the chlorine interacts with the body and the air. The risk shifts from simple ingestion to more complex routes of exposure involving the lungs and skin.
How Chlorine Becomes Airborne in the Shower
The primary mechanism of exposure during a shower is the volatilization, or “gassing off,” of chlorine and its byproducts due to the elevated temperature of the water. Chlorine is naturally volatile, and when hot water is sprayed into the air, the heat accelerates its transformation from a dissolved liquid state into a gas or vapor. This process concentrates the chlorine and its related compounds in the confined space of the shower stall and bathroom air.
The concern extends beyond chlorine to the compounds known as Disinfection Byproducts (DBPs). These are formed when chlorine or chloramines react with naturally occurring organic matter, such as decaying vegetation, present in the source water. The most well-studied DBPs are trihalomethanes (THMs), which include chloroform, and haloacetic acids (HAAs). THMs are particularly volatile and readily move into the air, leading to inhalation exposure.
Exposure in the shower occurs through both inhalation and dermal absorption. The warm water causes skin pores to open, which may accelerate the absorption of dissolved chemicals directly into the bloodstream. However, the inhalation of volatile compounds like THMs is often considered the more significant route of exposure in the shower setting. Heating the water has been shown to increase the concentration of THMs in the water, sometimes by as much as 50% compared to cold water, further contributing to the vaporized exposure.
Specific Health Concerns from Showering in Chlorinated Water
The most immediate and common negative outcomes from showering in chlorinated water are related to the skin and hair. Chlorine acts as a powerful oxidant and can strip the natural protective oils, or sebum, from the skin and scalp. This loss of the skin’s moisture barrier often results in dryness, flakiness, and general irritation. For individuals with pre-existing skin conditions like eczema or psoriasis, the repeated exposure to chlorinated water can exacerbate these symptoms and cause flare-ups.
Chlorine impacts hair by removing the natural oils that keep it moisturized and elastic. The result is often dry, brittle hair that is more prone to breakage and loss of natural shine. This chemical interaction can also damage the protein structure of the hair shaft over time.
Inhaling the heated chlorine vapor and DBPs, such as THMs, can irritate the sensitive tissues of the respiratory tract and bronchial passages. This is a particular concern for vulnerable populations, including young children, the elderly, and those with chronic respiratory diseases. Exposure has been linked to the irritation of airways, which may trigger coughing, wheezing, and the exacerbation of asthma symptoms.
Long-term exposure to inhaled DBPs has raised concerns regarding systemic health effects. While the Environmental Protection Agency (EPA) regulates DBPs in drinking water due to their potential link to certain cancers, the risk associated specifically with shower inhalation is difficult to quantify. Studies have suggested a possible link between long-term exposure to THMs and an increased risk of bladder and rectal cancer, though the primary route of concern is often ingestion. The fact that volatile THMs are concentrated in shower steam means this route of exposure warrants attention.
Reducing Exposure to Chlorine While Showering
For individuals concerned about exposure, several practical steps can be taken to reduce the levels of chlorine and its byproducts in the shower environment. One of the most effective solutions is installing a point-of-use shower head filter designed to remove chlorine. These filters typically utilize specialized media to neutralize the chemical.
Common filtration media include Kinetic Degradation Fluxion (KDF), which uses a redox process to convert free chlorine into harmless chloride ions. Activated carbon, which works by adsorption, is also highly effective at removing chlorine and organic compounds, though its efficiency can be reduced at higher temperatures. Many high-quality filters combine both KDF and activated carbon to provide comprehensive removal of chlorine, chloramines, and other volatile chemicals. Filters must be regularly maintained and replaced, typically every three to six months, to ensure the filtration media remains effective.
Behavioral Adjustments
Behavioral adjustments can also significantly lower exposure by managing the concentration of airborne vapors. Using an exhaust fan or opening a window during and after showering is important for actively ventilating the bathroom and dispersing volatile compounds. Reducing the temperature of the water can decrease the rate at which chlorine and THMs volatilize. Taking shorter showers limits the total duration of exposure to the concentrated steam.