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My city provides safe, clean water that is frequently tested. But I keep hearing that it's not actually safe to drink from the tap, because many houses have old or badly constructed pipes that contain heavy metals or dirt, or are a breeding ground for bacteria.

Is this something I actually need to be worried about? Are there studies on the percentage of households where the water is polluted because of issues with the pipes or similar problems despite a safe common water supply?

I'd be especially interested in the answer for my own country, Germany, but also in more general statistics or studies in other countries.

  • I'd be interested to see on what grounds the lack of safety is judged. And some references. – matt_black Oct 17 '11 at 22:02
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    I've always thought of this particular meme as a way to sell bottled water, that a person should drink bottled water because it's safer than the tap. Ironic, since some bottled water is just tap water (cnn.com/2007/HEALTH/07/27/pepsico.aquafina.reut) – mmr Oct 17 '11 at 23:39
  • @matt, I was trying to investigate whether Adelaide water (safe to drink, but notoriously bad tasting and hard) was still bad or whether the reputation was just slow to die out. I found the number of tests for different pollutants performed by the different authorities across Australia was staggering. It is almost like they took the quality of the drinking water supply seriously! My point is - there are lots of different grounds - and your local water authority probably has public reports. – Oddthinking Oct 18 '11 at 6:04
  • if tapwater were inherently unsafe, generations of people in western Europe and north America, all of whom have been drinking the stuff for decades, would have been chronically ill if not dead. Ergo, logic tells it's indeed quite safe. – jwenting Oct 19 '11 at 7:55
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Source - Water UK Consumer's Guide

Lead Contamination of Drinking Water

There is no lead in water when it leaves the water treatment works. However lead can be picked up by the water if the service pipe (the pipe connecting your property to the main in the street), is made of lead. Lead can also be picked up from any internal lead pipework and lead-based soldered pipe joints inside your home.

If your home was built before 1970 it may have lead pipes. If it was built after 1970 it is unlikely to have lead pipes.

Other Issues Affecting Drinking Water

Taps:

It is important that taps that are used for drinking water are kept clean. Whilst the water coming to your tap is safe, many bacteria can live in the kitchen and some can grow both on the outside of the tap and inside the lip of the spout.

Water Storage:

Ideally you should only use a mains fed tap for drinking water. However if your drinking water, or water for brushing your teeth, comes from a storage tank, you should check the following:

Is your tank in good condition?

Nowadays, tanks are constructed of plastic (polyethylene) and are unlikely to cause problems provided that they are designed for drinking water purposes and have a closely fitting cover.

Is the tank covered?

Ensure your tank has a close-fitting lid of a suitable material that will not deteriorate or allow mould or bacteria to grow on it and drip into the water. The lid must prevent debris falling in and polluting the water supply. It is not uncommon for birds, rodents or insects to find their way into tanks that are uncovered or only partially covered.

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1) Unless it's continously tested, "frequently" doesn't cut it. Safe, clean water can get contaminated, from either accidents, sabotage, or engineering failures.

The most spectacular example is British town of Camelford in 1988 (the story is very harrowingly detailed here: http://www.cracked.com/article_19157_the-5-biggest-backfires-in-history-disaster-relief_p2.html )

2) Testing only happens for what the regulations require to test.

  • http://environment.about.com/od/healthenvironment/a/tap_water_safe.htm

    Tap water is not without its problems. In 2005, the nonprofit Environmental Working Group (EWG) tested municipal water in 42 states and detected some 260 contaminants in public water supplies. Of those, 141 were unregulated chemicals for which public health officials have no safety standards, much less methods for removing them.

  • AP: Drugs found in drinking water

    A vast array of pharmaceuticals — including antibiotics, anti-convulsants, mood stabilizers and sex hormones — have been found in the drinking water supplies of at least 41 million Americans, an Associated Press investigation shows.

    To be sure, the concentrations of these pharmaceuticals are tiny, measured in quantities of parts per billion or trillion, far below the levels of a medical dose. Also, utilities insist their water is safe

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    This doesn't really answer the question, which I read to be asking whether local contamination is a realistic concern for an otherwise safe water supply. – Flimzy Oct 17 '11 at 23:13
  • @Flimzy - See #1. It was an otherwise safe water supply. – user5341 Oct 18 '11 at 0:19
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    camelford was a very rare and very spectacular screw up. I don't think an event that occurs perhaps once in 3 decades really answers the spirit of the question. – matt_black Oct 18 '11 at 5:15
  • @dvk I'm not asking about the municipal water supply - yes, there's possibilities of a screw-up or contaminants we don't know how to test for there, too, but at least it IS tested constantly. I'm asking about the completely untested-after-flowing-through-dubious-pipes water from the tap. – Cass Oct 18 '11 at 7:20

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