Q. I have boiled water in the microwave in the past and found it to be fast and effective but I have been told that this isn’t a good idea and not very safe. I don’t really see why, is it true? Can you boil water in the microwave safely or can it cause problems? It’s quite convenient and I have never had any problems so far.
A. The technical answer is yes, you can boil water in the microwave. However, deciding whether you should is a more complicated question. What you might have been told is that water boiled in the microwave has exploded or burst into a person’s face and caused injury when the vessel has been removed, agitated or something has been placed into the water.
To understand why this might happen, we need to understand how the process of water boiling occurs. When we boil water on the stove or in a kettle, it heats gradually, we begin to see bubbles form and gradually increase in size. These a vapour bubbles being released as the heat energy of the water increases. Once we see the bubbling happening at a rapid rate, we know it is boiled and take the water off the heat for use.
In a microwave, however, the heating process is much quicker and the vapour bubbles aren’t released in this slow and steady manner. This can mean that the water doesn’t appear to be heated at 100 degrees C but can actually have become even hotter. When you take it out of the microwave, the vapour bubbles can all rush to the surface at once and cause a huge splash of extremely hot water that can scald you very badly.
While some microwave manufacturers may give directions on boiling water in the microwave, others may recommend avoiding this altogether. We think it is safer to use a regular stove or kettle to be on the safe side. Are those few extra minutes really worth the risk of a trip to hospital with a nasty injury? If you do decide to use this method, ensure you follow manufacturers’ instructions and as a precaution, leave the water to stand inside the microwave with the door open for two minutes to allow a little cooling time and make sure everyone in your home understands the risks. It is also best not to allow children to boil water in the microwave as an extra precaution.