While traveling, you come across many different levels of water safety. In some countries you can drink the tap water, and in others you should avoid it at all costs.

Where do you draw the line when you know the water isn't safe to drink?

  • Brushing your teeth?
  • Washing dishes?
  • Washing your hands?
  • Washing clothes?

Do you also have to avoid eating anything that's liquid unless it's hot?

I'll give an example. I'm staying at a guesthouse in Bali that has a shared kitchen. There's a sign specifically stating that the water is non-potable, but we are asked to wash our dishes there. So the same cups I would use for eating and drinking have been washed with water that isn't safe. I've been doing it for a week and have been fine.

  • I am assuming that your definition of non potable water is tap water, you can use tap water for anything ... as long as you dont drink it.
    – user2704
    Jun 28, 2012 at 7:16
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    @user2704 - depends entirely on the country. Here in Scotland, tap water is likely to be better for you than many bottled waters!
    – Rory Alsop
    Dec 31, 2012 at 19:51
  • Agree with Rory. Tap water in most western countries is required to be acceptable for drinking, since it's also used for cooking. The bottled water they sell in supermarkets there is just a rip-off. Jan 3, 2013 at 4:38

4 Answers 4


This is hard to answer with an authoritative source since the quality of non-potable water varies widely from the source it comes from (is it groundwater? river water? is there anything recycled from drainwater from houses?) and even within a country.

I'm speaking mostly from my experience living in India, but in practice I have seen similar practices in Malaysia, Indonesia, Vietnam and Thailand too. None of these places have potable water supply; the source is typically river or lake water. The reason why they are classed non-potable is primarily because of high mineral content or particulate matter, which can be purified for human consumption by physical filtration as opposed to bacterial disinfection - although as it has become cheaper and more compact to make ultraviolet or reverse osmosis filters for home use, these are also used. Bacteria or viruses are the causes for most water-borne diseases, those can get into the water supply if untreated raw sewage is dumped into water sources which thankfully most civil authorities are not stupid enough to do.

So for the countries I mentioned, in practice, while it is customary to purify water for drinking either by boiling or using filtration devices, for other purposes such as washing clothes, washing dishes, cleaning hands, bathing, brushing teeth et al - essentially, anything that does not involve ingesting water, tap water is used directly. The water may taste funny for instance if you're brushing your teeth - that's because of the high mineral or iron content typically - but as for safety, yes, it can be considered safe.

  • 3
    A very rough bottom line could be indeed swallowing the water. Many sources also mention washing vegetables in a teated water. It is always under the assumption that the water is not contaminated, but only not-potable in one way or another.
    – crenate
    Feb 22, 2012 at 10:03
  • 1
    Brushing teeth usually implies swallowing at least some water. How does this not lead to infections? Jun 19, 2017 at 7:32

You don't have to leave North America to find non-potable water - the cottage I used to visit for decades drew its water from the lake, and this was used for showers, toilet flushing, dishwashing, and even for water-that-would-be-boiled eg for pasta or mashed potatoes. Eventually it developed a colour that nobody liked and we switched to using bottled water for cooking, but given the trouble and expense that bottled water entailed, nobody would fill a sink with it for dishes. Plus the cottage had a water heater, so the non-potable tap water was hot!

The compromise we came to was to wash in the hot tap water with plenty of soap, and when someone vulnerable (say, over 70, or pregnant, or a small child) would be using the dishes, to give them a quick rinse with bottled water afterwards just to be on the safe side. If this is practical at your shared beach house, I recommend it.


You could use non-potable/grey water for flushing toilets, taking a bath, washing the floor, etc.


Generally non-portable water is not treated or has any purification. Well water is a good example where water taken from a bore hole on a farm is used for irrigation and not for drinking.

Drinking water has had treatment to remove any pathogens that may exist in the water that is drawn from a bore hole. Bacteria can live in extreme conditions and if is well known that bacteria can live in water, so drinking water will be treated to minimise the risk of these water borne pathogens from being able to spread though a drinking water system.

You can treat non-portable water with water purification systems and filtering systems.

Bottled water is not necessarily pure or better than tap water from a country that produces potable water as a standard. It is a myth that bottle water is better for you, therefore it is always best if you're not sure, to buy bottled water that is certified as treated for drinking.

If in doubt use water purification tablets.

  • 4
    Welcome to Travel, Mark! Your answer contains helpful information on potable water, but doesn't really answer the question: given a tap which produces non potable water, what is it safe to use that water for? Perhaps you could edit your answer a little? Dec 31, 2012 at 17:28

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