I live in Bombay, India. We boil our water here, and have done so for many years. I'm wondering if a serious water purifier e.g. RO + UV would be a better way to go. In this context, better means, better for the health of the human (or possibly animal) who is consuming that water. We occasionally have international guests, and sometimes they seem unhappy with boiled water as a option. Or is both boiling and purification the best way to go?

There is some discussion of this on the net, but I'm looking for a detailed answer, with pros and cons. I haven't found anything like this. Also, some of the answers I've felt have been on sites which might be biased, like sites selling water purification technology.

An Indian-specific answer would be ideal, but not necessary. I do know that Bombay water is supposedly very bad. I've never tested it, though.

As I understand it, the main disadvantage of boiling water is that it doesn't get rid of dissolved solids and other possibly dangerous impurities. And the corresponding disadvantage of RO water purification is that it gets rid of all minerals, which is presumably bad. And it apparently possible to remineralize the water, but I don't know how much of an issue it is in practice. There might be other issues that I'm not aware of.

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    You need to boil this down to a single specific question rather than asking for a comprehensive overview with pros and cons. Pros and cons are usually matters of opinion. Also, clarify what you mean by "better." Better in what way? Healthier?
    – Carey Gregory
    Oct 17, 2017 at 18:03
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    @Paparazzi Thank you, that's a very helpful link. Oct 17, 2017 at 21:05
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    @FaheemMitha Asking for a comprehensive overview sounds like a lot more than simply "which is better," and as I said, pros and cons are usually matters of opinion. Plus you added that last bit about acidity, which seems to be another question. The question just strikes me as overly broad.
    – Carey Gregory
    Oct 17, 2017 at 21:15
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    I'm voting to close this question as off-topic because purification processes are chemical processes and therefore off-topic here. As @CareyGregory pointed out, the great outdoors it even Chemistry.SE is a much better fit.
    – Narusan
    Oct 18, 2017 at 5:11

1 Answer 1


The hazards from drinking water in Mumbai in 2012-2013 were identified as

Officials said the contaminants found in Mumbai's water were sand particles, sewage water, E.coli, other bacterial content besides other foreign particles. Among the deadliest of these, E.coli can cause severe abdominal cramps, bloody diarrhoea and vomiting, said doctors.

Boiling for one minute will kill/inactivate E Coli and other water borne pathogens

Boiling water kills or inactivates viruses, bacteria, protozoa and other pathogens by using heat to damage structural components and disrupt essential life processes (e.g. denature proteins). Boiling is not sterilization and is more accurately characterized as pasteurization. Sterilization kills all the organisms present, while pasteurization kills those organisms that can cause harm to humans. Cooking food is also a form of pasteurization. For pasteurization to be effective, water or food must be heated to at least the pasteurization temperature for the organisms of concern and held at that temperature for a prescribed interval.

However, you're going to need some type of filter to remove sand particles or chemicals that might be in your water. Some people believe that it's better to filter out chlorine ( though a lack of effective chlorination is Mumbai's problem ) as it might affect the intestinal biome and contribute to disease, but this is speculation at present. However, water left to stand for some hours will allow chlorine to dissipate.

  • Thanks for the answer. Although I'm not sure what you mean by "though a lack of efficient chlorination is Mumbai's problem". Do you mean that they chlorinate it, but don't do so properly? Oct 18, 2017 at 8:41
  • I don't think I've read this article before. "C ward, which includes areas such as Pydhonie and Bhuleshwar, was revealed as the area receiving the dirtiest water from taps." Unfortunately, we're C ward. Oct 18, 2017 at 8:44
  • Yes, as I said the chlorination is not being done effectively Oct 18, 2017 at 8:56

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