In an attempt to ward off illnesses caused by bacteria, people resort to all sorts of methods to sanitise water and make it safe for consumption. Boiling water, exposing it to UV lights and filtering it through special filter media are the most common ways to destroy disease-causing bacteria and viruses present in tap water. But what about freezing water? Can freezing water be an efficient way to kill bacteria?
Many people use unfiltered tap water in icemakers being convinced that by freezing water, bacteria in it will be destroyed. Unfortunately, freezing water will not help in getting rid of bacteria, and it will not make tap water safe to drink. As a result, freezing water is not an acceptable way to sanitise or purify water.
What happens to bacteria when water is frozen?
Although freezing water can damage living cells by ice crystals breaking the cell walls resulting in the killing of some bacteria (usually larger parasites), other bacteria can withstand prolonged exposure to freezing temperatures. In fact, some viruses discovered with the melting of the ice caps can be traced back to prehistoric times. In 2015, a 30,000 years old virus was discovered in the Siberian permafrost, and although the virus, dubbed Mollivirus sibericum, is not a threat to humans since it infected single-cell amoebas during the late Stone Age, it goes to show how resilient can some microorganism be and how they can survive even in harsh environments.
At its best, freezing water that contains bacteria will slow down or prevent them from multiplying putting them into a dormant phase, however, when thawed, bacteria will reactive and multiplication will resume.
Effective ways to kill microorganisms in tap water
Municipal water suppliers rely on chlorine as a chemical means to disinfect water and destroy pathogenic bacteria. While it’s the cheapest and one of the most effective ways to protect against water-borne diseases used today, chlorine is not without its risks for the human health, and not all microorganisms can be efficiently dealt with by adding the same concentration of chlorine to water.
Based on the above considerations, if you want to kill bacteria in your tap water, freezing it is not the answer. In contrast, boiling water for a certain period and exposing it to UV lights, are two of the most efficient ways to sanitise water. However, boiling water is not recommended if your tap water contains certain contaminants whose concentration is only increased through boiling (e.g. heavy metals). This leaves ultraviolet water filters as the most efficient, eco-friendliest and healthiest way to solve microbiological issues with your tap water.