World Water Week: What's in Your Tap?

By Liz Borkowski

Aman at Technology, Health & Development reminds us that itâs World Water Week, and provides a great collection of water-related links for the occasion. Several of the articles are about a backlash against bottled water â apparently, a critical mass of people has just discovered that a) tap water is often as clean, if not cleaner, than bottled water and b) that buying bottled water is wasteful.

Now that weâre all quenching our thirst with tap water again, this might be a good time to look at a few concerns that have been arising about municipal water supplies.

Angry Toxicologist highlights the issue of disinfection byproducts (DBPs) in tap water: 

Most cities and towns use chlorine or bromine to disinfect water. When the water is polluted, chlorine or bromine reacts with the pollution (agricultural runoff is probably a bigger problem here than traditional industrial pollution) to create what are called disinfection by-products (DBPs). DBPs are associated in humans with adverse pregnancy outcomes (usually miscarriage).

⦠and has this advice:

Women, drink purified water while pregnant or trying to get pregnant**; men who are trying, drink any water you want, unless it's after the heavy fertilizing in the spring when many DBPs go over EPA limits (many water testers know when this is coming so they test around it. You can't totally rely on the water report you get).

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** When I say purified water I don't mean bottled spring water or distilled water or purified by Britta filters or any of that stuff. I mean the 1 or 2.5 gallon jugs labeled "drinking water". It's usually purified by reverse osmosis (which is the best way to do it), and it's the cheapest water you can buy at the store (usually can be found as a generic brand). Britta will get out a lot of DBPs but there's a lot of junk it doesn't get out. Most bottled water (Aquafina, Poland Spring,...ETC) is just some other place's tap water.

Over the past few years, some water suppliers have switched from chlorine to chloramine (a mixture of chlorine and ammonia) for disinfection because chloramine is less reactive and thus forms fewer DBPs. It seems, though, that chloramine comes with its own set of issues.

In 2004, D.C. residents learned that tap water in thousands of our homes had tested above the federal limit for lead contamination. Officials eventually concluded that the 2000 switch to chloramine, undertaken to comply with the 1998 Disinfection Byproducts Rule, had made the water more corrosive and caused mineral scales inside lead service lines to dissolve. Approximately 23,000 out of 130,000 water lines were made of lead, and officials stepped up work to replace them. Rebecca Renner of Environmental Science & Technology stuck with the story, noting that many of the homes with high lead concentrations in their tap water did not have lead service lines:

The change in disinfectant did cause mineral scales inside D.C. lead service lines to dissolve, says corrosion expert Michael Schock with EPAâs Office of Research and Development. However, the more-corrosive water also eroded lead solder, which sent particles down the pipes, and leached the metal from brass plumbing in homes. He points out that brass faucet bodies and necks, shutoff valves, water meters, and other plumbing components usually contain lead, even if the brass is labeled lead-free. That is because Congress defined in the 1996 Safe Drinking Water Act amendments that âlead-freeâ plumbing pipes and components could have up to 8% lead.

Water treatment changes to reduce DBPs have also raised lead levels in Stafford, Virginia and in Durham and Greenville, North Carolina. In these cases, the cities also changed coagulants at the same time that they switched to chloramine.

Plus, in addition to unexpected results with lead, changes to non-chlorine disinfection methods have resulted in new DBPs, reports ES&Tâs Naomi Lubick. These substances will need to be studied to see whether theyâre associated with adverse health effects, and then some cities might be in for another round of changes.

As Angry Toxicologist points out, water providers have the tough job of turning polluted water into something that wonât make us violently ill. In the global context, weâre lucky to be worrying about the effects of DBPs rather than cholera.

As the lead-in-tap-water saga unfolded here in DC, I realized that although I was attuned to global water issues, I hadnât paid much attention to the water coming out of my own tap. I know more now about where this water comes from and how itâs treated â and I actually read through the consumer confidence report I get in the mail each year. If youâre a U.S. resident and would like to learn more about the laws governing drinking water or your local drinking water system, the EPAâs website is a good place to start.

Liz Borkowski works for the Project on Scientific Knowledge and Public Policy (SKAPP) at George Washington Universityâs School of Public Health and Health Services.