Monday, May 31, 2021

Should you boil your tap water?

After my interview by CNA, some questions came in about the necessity of boiling tap water. 

Are there benefits to it? Does boiling mitigate the effects of contaminants from piping and water tanks?

  1. First off, let's be clear that boiling water has been a tradition in Singapore for a long time, probably dating to before independence, and for good reasons. In the old days, not everyone had access to tap water. Whatever water sources (rivers, ponds, wells) in those days were probably low in sanitary standards, if any. Imagine someone bathing and defecating into the river that you obtain your drinking water from. Piping and water tanks were probably poorly maintained.

    This combination of conditions were recipes for outbreaks of water borne diseases like cholera, dysentery etc. The main culprits were of course pathogenic microbes transmitted via contaminated water and food. The good news is such microbes can be killed by boiling. As long the boiled water does not get recontaminated, you are safe from these nasty water borne diseases with colourful nicknames like bloody diarrhea or rice water-like stools. Not surprisingly, boiling water has become a standard practice that persists even after every household on the mainland is served by tap water.

    Check out this post by Rice Media: A brief history of lao sai, explained if you want to get down and dirty for the details.

  2.  However... boiling does nothing to the rest of the non-microbial contaminants in the tap water. If your piping and water tanks are rusty, rust will go into your tap water. Not that rust is a real health concern, it is just that boiling does not remove it. Neither does boiling remove heavy metals, pesticides or most radioactive substances. It certainly does not remove fluoride (hey, we need fluoride to REMAIN in the water for healthy teeth, remember?) and only removes a small percentage of chlorine.

  3. Is boiling necessary then?

    If we go by the study by CNA of which my interview is part of the programme, the bacteria count is either undetected or low in the tap water. Please keep in mind that these bacteria are probably harmless. Of course, if you are concerned about the maintenance of the water tanks, equipment and piping leading to your household, by all means, go ahead and boil your tap water. Maintenance is ultimately performed by humans and there is always a possibility of human error.

    As mentioned above, if you decide to boil your water, make sure your boiled water does not become recontaminated in whatever container you are using. 
Figure: Boiling water in this vintage kettle from the old days


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