In Mexico City, water from the tap is not fit for consumption. You don't even use it to make your coffee or boil your vegetables -water in this city has a slightly foul smell, reminiscent of ancient decaying swamps and natural gas.And to make the taste even worse, it's also heavily chlorinated.
You buy jugs of spring water in the shops -a heavy haul- or have a company deliver the water to your home -also a drawback, as they will not deliver anything if there's nobody home.