It is a common question whether simply boiling tap water can make it safe to drink. Many people wonder if this simple household method is effective enough to address potential concerns about water quality. Understanding the capabilities and limitations of boiling water is important for ensuring the safety of your drinking supply.
How Boiling Makes Water Safe to Drink
Boiling water primarily works by eliminating harmful microorganisms that can cause illness. The high temperatures achieved during boiling are lethal to most bacteria, viruses, and parasites commonly found in contaminated water. This includes pathogens such as Escherichia coli (E. coli), Giardia lamblia, Cryptosporidium parvum, and Norovirus, all of which can lead to gastrointestinal diseases.
The scientific principle behind this effectiveness lies in the denaturing of proteins and the destruction of cellular structures within these microorganisms. Heat disrupts the complex molecular components that are essential for their survival and replication. Sustaining a rolling boil for a specific duration ensures that these biological threats are effectively neutralized, rendering the water microbiologically safe for consumption.
What Boiling Does Not Remove
While effective against biological threats, boiling water does not remove chemical pollutants or heavy metals. Substances like lead, arsenic, nitrates, pesticides, and various industrial chemicals are non-volatile, meaning they do not evaporate at water’s boiling point. In fact, as water boils and evaporates, these non-volatile contaminants can become more concentrated in the remaining water.
For example, if water contains lead, boiling it will not remove the lead; instead, the concentration of lead in the reduced volume of water will increase. Similarly, nitrates are not eliminated by boiling and can become more concentrated. Boiling also has limited effectiveness in removing volatile organic compounds (VOCs) or trihalomethanes. Therefore, boiling alone cannot make chemically contaminated or turbid water safe.
When to Boil Your Tap Water
Boiling tap water is most often recommended during specific situations when the public water supply is compromised. Local authorities, such as public health departments, issue “boil water advisories” when there is a known or suspected contamination of the drinking water system. These advisories are typically prompted by events like water main breaks, power outages that affect water treatment plants, or natural disasters such as floods or severe storms.
During such advisories, the integrity of the water treatment and distribution system may be compromised, increasing the risk of microbial contamination. Boiling is also advisable if you are drawing water from an unknown or questionable source, such as during camping or in emergency preparedness scenarios where regular treated water is unavailable.
Steps for Boiling Water Safely
To effectively make water safe through boiling, bring the water to a rolling boil. This means the water is bubbling vigorously and continuously. Maintain this rolling boil for at least one minute at sea level to ensure the destruction of most disease-causing microorganisms.
If you are at altitudes above 6,500 feet, boil the water for three minutes, as water boils at a lower temperature at higher elevations, requiring a longer duration for purification. After boiling, allow the water to cool naturally before use. Store the cooled, boiled water in clean, disinfected, covered containers to prevent re-contamination from the environment. If the water is visibly cloudy, filter it first through a clean cloth, paper towel, or coffee filter to remove sediment before boiling.