What can I do to make sure the water from the municipal system is safe to drink?

If you’re worried about your own drinking water, you can have it tested.

E. coli, shigella, cryptosporidium, and giardia don’t have any taste and they’re invisible, so you can’t tell if they’re in your water by looking or drinking.

If your water comes from a municipal system, it is tested on a regular basis anyway, but you might want to know what effect your own plumbing has on your water and do a test on a sample directly out of your own tap. People buying a new house might want the water tested before they sign a contract of sale.

If you are pregnant, planning to become pregnant, or have an infant less than six months old, testing well water for nitrate and coliform bacteria is important, pregnant women and infants should not drink water that has nitrate concentrations of higher than 44 parts per million.

Those with wells that might be subject to contamination from nearby dumps, landfills, factories, dry cleaning operations, livestock pens, septic fields, mining operations, heavily salted roadways, or fuel storage tanks might also want to periodically test their water. If the water is staining your sink or your clothing, or if it looks cloudy or colored, these may also be reasons to test to see what’s causing the problem.

Most state health departments will test water, either by collecting it themselves or having you bring a sample in to be tested. There are also private labs that will do the testing. You can’t just say “test my water,” though.

You have to decide what you want the water tested for. There are hundreds of possible pollutants, and a corresponding number of tests to detect them. The most common (and cheapest) tests are for coliform bacteria and nitrates, but the tests can get quite elaborate and expensive when you get into testing for the many industrial and agricultural pollutants than can turn up in drinking water. In private labs, these tests can cost anywhere from $30 or less for the simplest tests up to $600 and more for the most elaborate.

Collection procedures and testing methods may vary from one lab to another, and it’s important to collect the sample exactly as directed to get accurate results. Like any other area where there is money to be made, the water-testing field has attracted its share of questionable claims and dubious practitioners.

Non-chemical water treatment devices are for sale that claim to eliminate various problems with magnetic impulses, electrostatic fields, or some other kind of force. People who sell worthless merchandise by making unscientific claims should be treated with the contempt they deserve. If you have doubts about a lab or a piece of equipment, the state health department can be a source of sound advice.

The latest report on surveillance for waterborne illness published by the CDC came out in May 2000 and covers the years 1997–1998. Thirteen states reported 17 outbreaks of illness associated with drinking water, mostly during the summer and fall months.

Fifteen of the outbreaks occurred between May and October. No one knows the reason for five of the outbreaks. Of the other 12, copper poisoning caused two, and the remaining 10 were caused by parasites and bacteria: four by giardia, two by cryptosporidium, three by E. coli O157:H7, and one by S. sonnei.

This seems like quite a few outbreaks, but as we will see, at least as many and often more people get sick by swimming in polluted water than by drinking it.