Tap or Bottle: Which Water Should You Drink?

Doctors often advise drinking at least 1.5 liters of water per day, and it is wise advice: dehydration can be a serious health issue. Advertising pushes us to buy bottled water, insisting that tap water is not safe. Is it worth spending money on those bottles?

Over 60% of our body mass is water, but throughout the day we lose over 1.5 liters of water through breath, kidneys, and sweat (more on water balance here). This can be replenished through food and drinks; however, pure water has the advantage of not containing calories. Many people believe you should opt for bottled water. Are they right?

Is tap water dangerous?

In developed countries, such as the US, the EU, etc., the quality of tap water is controlled by state authority; controls are frequent, standards strict, and compliance high. In the UK, for example, 2014 controls showed 99.96% compliance (more info here). Further, tap water is often fortified with fluoride, which helps prevent tooth decay. Besides, it is fresh: it takes water no more than a couple of days to go from the plant to your faucet.

There are caveats, though. A study in the US in 2016 showed the presence of toxic chemicals called PFAS in samples from 33 states. Another study found 1,4-dioxane – a probable carcinogen – in 45 states. These chemicals probably leach from the surrounding land under industries and cultivation. And while lead pipes in most places have been replaced with plastic ones, for many people tap water is still a source of 20% of their lead intake.

Is bottled water better?

Unfortunately, no. First of all, up to 30% of bottled water in the US is actually tap water (producers are not obliged to state it on the label, but if you see “municipal source” or “purified”, it means it comes from the same source as tap water), which means it will contain the same chemicals. Second, the plastic used to make the bottles has been found to leach chemicals that act as a synthetic estrogen (female hormone), which can reduce fertility (see the study). The danger is higher when a bottle is exposed to sunlight and high temperatures.

Bottled water production is a burden on the environment, too. Bottles are made using crude oil; according to estimates, just in the US, over 17 million barrels are used for this purpose annually. Next, you have to factor in energy consumption and transportation costs, water used for production (each liter sold costs 3l of water), and CO2 emitted.

What should you choose?

To make sure your tap water is safe, check the regular water quality report published by your municipality. If no dangerous chemicals were found, go for tap water, but try to drink from a glass or from a stainless-steel bottle (if you reuse a plastic bottle, don’t leave it in the sun in or a car).

If tap water is not safe where you live, read the label on bottled water carefully to ensure it comes from a spring and contains both magnesium and calcium. Remember, though: while it may taste better than tap water, you are not doing the planet any favors buying it.