Link to Google Map of Turbidity on the University of Cincinnati's website

Dozens of molecules with scary-sounding names, but nearly always in quantities so small that they’re deemed safe by the Environment Protection Agency.

For some molecules, the name may indeed be more scary than the molecule itself, and for some we don’t really know yet–there are no restricted levels on all possible contaminants. In any case, there is one relatively cheap way to improve your drinking water even further, by buying an NSF-approved home filter.

Tip-Top tap waters

I turns out you should worry more about the water from a hand-pump in the National Park campground than about the one flowing out of the tap in a big city. Smaller utilities and water from wells sometimes come closer to the allowed limit for some contaminants, because they may not afford to invest in expensive equipment.

Link to Google Map on the University of Cincinnati's website

Still, a study by the University of Cincinnati and Procter & Gamble researchers found all tested waters to be within federal health limits, and therefore safe to drink: “I believe the overall picture for US drinking water quality in the US is good,” says lead author Scott Dyer of Procter & Gamble. (Note: Procter & Gamble markets the “PUR” line of home water filters, one of the main brands on the market with “BRITA.”)

The authors of the study started looking at many utilities around Cincinnati, including some supplying water to only a hundred homes. They then enlarged the study, but to be make it relevant to more people, they focused on 77 urban areas in the US.

Find out if your city is one of these 77.

Note that the concentrations used are reported by the utilities themselves–as required by federal regulation–and date back to 2004-2006. The report took into account 392 water utilities that serve 62% of the population.

Costs and benefits

You wouldn’t fill your bathtub with spring water. Yet you flush drinking water down your toilets, use it for washing clothes, dishes and your skin. It would be even more irresponsible to ask for all that water to be absolutely pure. All drinking waters are exposed to contaminants, whether from pipes, bottles or contact with the environment. Purifying beyond a certain point is counterproductive: both useless and prohibitively expensive.

A more cheaper solution is to use a filter at home, and treat only that water which you are going to drink. A filter containing what is called “activated carbon” and “ion-exchange resins” is the easiest, most affordable solution to raise your drinking water quality above federal standards.

Link to the results for Boston on the University of Cincinnati's webpage

If you find out that your tap water (on the right is a diagram of the results for Boston) contains high levels of some unwanted contaminants, you may consider getting a filter that removes the incriminated contaminants. Just make sure it is NSF-certified and doesn’t rob your water of its healthy minerals (most filters won’t).

What’s good for you is not good for your dishwasher

You should drink water that is free from microbes and various organic molecules seeping from farms and factories. Yet you do want some of the minerals–not lead or arsenic, but at least calcium and magnesium.

When spring water contains lots of minerals it’s called mineral water. With minerals such as calcium and magnesium, water is beneficial to your heart. Even companies that bottle tap water after purifying it also often add some of these minerals back–check the labels to see how much. Don’t get too crazy about this, though: with a balanced diet, you should get a lot of these minerals from food rather than from water.

The simpler and cheaper way is to drink tap water: when tap water contains lots of calcium and magnesium, it is called hard. So if you live in an area with hard tap water, by all means, drink it! A proper filter shouldn’t remove these healthy minerals.

On the other hand, if the water in your area is hard, you may want to install a water softener on the pipes that feed your dishwasher and other appliances, because the calcium and magnesium in hard water clogs these.

“I can see clearly now the rain is gone”

“One cannot tell if water is safe just because it appears clear or tastes good,” says Rick Andrew from the National Science Foundation.

#1 Bubbles: Your water may appear cloudy, but colorless. Most likely, the pressure in the mains has increased so that minuscule bubbles form when the waters exits your tap and reaches normal pressure.

Bottom Line: Leave your glass aside for a minute or two and see if the bubbles coalesce and finally clear up. If that’s the case, you’re fine, but if the cloudiness remains and is accompanied with color, go to step #2.

#2 Soil: Heavy rains may have caused soil runoff, or maybe there’s repair work being done on the water mains: the little submarines floating in your glass are soil particles, and they may have brought microbes along for a ride.

Bottom Line: You may see soil particles, but you can’t see germs, so check item #7. You may also want to get a filter.

#3 Iron: Iron oxide can seep into some wells and color the water a rusty brown-orange and give it a metallic taste. To avoid this nuisance, federal standards recommend an upper limit on the iron content of water.

Bottom Line: Utilities have no obligation to follow the federal standards for taste, only those for health. There is no clear associated risk with iron–which is why water in some rural areas can taste funny–but if iron is leaching from a mine, there may be other metals around (see #8).

#4 Algae: Algae present in lakes and stream can give an unpleasant flavor to drinking water, if your water comes from reservoirs as opposed to wells.

Bottom Line: The presence of algae mostly causes an unpleasant odor, but it can also be accompanied by bacteria (see #7).

Not just a matter of taste

#5 Chlorine: Chlorine is added to disinfect tap water: water leaving the treatment plant without chlorine wouldn’t be so safe during its trip through the water mains. But chlorine brings an unpleasant taste and can produce unwanted byproducts that affect the nervous system, irritate the eyes or nose and increase the chances of cancer and anemia.

Bottom Line: You can use a home filter to remove chlorine and its byproducts right before you drink–just don’t leave the water standing for days, and pay attention to seasonal variations in waterborne germs (see #7).

#6 Copper: Corrosion attacks pipes, and copper may slowly dissolve into the water. This gives a metallic taste and even a blue-green color to your water. It can also upset your digestion, or even damage your liver and kidneys in the longer term.

Bottom Line: More recent pipes made out of PVC avoid the problem with copper, older ones containing lead may be worse (see #8).

Tasteless

#7 Microbes: Germs in human or animal excrement can trigger gastro-intestinal illnesses. Spikes in bacteria concentration may also stem from the seasonal blooming of algae on which some bacteria feed in lakes and streams. In areas that rely on surface water as opposed to groundwater, these bacteria can end up in tap water.

Bottom Line: In general, utilities will solve the safety issue, but make the flavor one worse–by adding chlorine to get rid of germs (see #5).

#8 Lead: If the pipes in your area are old and contain lead, this metal can find its way into your water–even if it was removed properly at the plant. Lead can delay a child’s development and affect an adult’s kidneys and blood pressure. Even though old water systems are more likely to have lead pipes, the tests reported by utilities may not reflect that since they’re often performed upstream at the plant.

Bottom Line: Pipe quality varies, and it is impossible to test the water in every single house. This may be a good reason to install a filter, unless you can convince someone to replace the pipes in your area (see #6).

Link to Google Map for Nitrate on the University of Cincinnati's website

#9 Residue from fertilizer and septic tanks: These produce nitrites and nitrates which can affect infants, leading to shortness of breath and blue-baby syndrome and possibly death. On the map drawn by the University of Cincinnati – Procter & Gamble team, these concentrations are clearly high in a teardrop-shaped region from Nebraska to Ohio, says team researcher Scott Dyer from Procter & Gamble, who explains this by fertilizers seeping into the cornbelt’s water table.

Bottom Line: As for many other contaminants, you can use a filter to remove most of it.

Everything you ever wanted to know about tap water

There are many other compounds to pay attention to. For instance, perchlorate, which is used in explosive and rocket fuel to provide extra oxygen, has been found in some tap waters. The Environmental Working Group’s Nneka Leiba is hoping that the EPA will enforce an upper limit on perchlorate concentrations in drinking water. She mentions 141 unregulated compounds found in tap water for which she would like to see standards enacted–yet for most of these, it is unclear what effect they have on our health, if any.

The Environmental Working Group’s report is a few years older than that of the University of Cincinnati, but it lists many more communities, and separates them according to 39,751 utilities, so you can find yours instead of reading about a city average. It also lists a broader range of compounds, including unregulated ones.

If you still cannot locate your utility, try via the EPA’s website.