Q: I've heard that drinking tap water is bad for you—is there any truth to this? Bottled water is so expensive, but I'll spend the extra money if it'll keep me healthy.

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Q: I've heard that drinking tap water is bad for you—is there any truth to this? Bottled water is so expensive, but I'll spend the extra money if it'll keep me healthy.

If you believe TV and print ads, all bottled water comes from remote mountain streams and pristine glaciers—this can easily make you assume that bottled water is healthier than tap. In reality, while most bottled water is of good quality, some contains contamination. One should not automatically assume bottled water to be purer or safer than water from the tap.

In fact, depending on where you live, tap water may be just fine. The Natural Resources Defense Council (NRDC), which has conducted extensive tests on both municipal water supplies and bottled water, says that, in the short term, if you are an adult with no special health conditions and you aren't pregnant, then you can drink most cities' tap water without having to worry. Most of the contaminants in public water supplies exist at such small concentrations that most people would have to ingest very large quantities for health problems to occur.

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The NRDC does caution, however, that pregnant women, young children, the elderly, people with chronic illnesses and those with weakened immune systems can be especially vulnerable to the risks posed by contaminated water. The group suggests that anyone who may be at risk obtain a copy of their city's annual water quality report and review it with their physician. To find out about your city's water quality, you should ask your water utility (the one that sends water bills to people in your community) for a copy of its annual water quality report, sometimes called a right-to-know report or consumer confidence report.

For those people who live in areas of poor water quality, home water filtration is an option. As a general rule, look for filters that are labeled as meeting NSF/ANSI standard 53 and certified to remove the contaminant(s) of concern in your water. Brita water filters can address the cause of bad tastes and odors, such as chlorine, and can also substantially reduce many hazardous contaminants (including heavy metals such as copper, lead and mercury), disinfection byproducts, parasites (such as Giardia and Cryptosporidium), pesticides, radon and volatile organic chemicals (such as methyl-tert-butyl ether (MTBE), dichlorobenzene and trichloroethylene (TCE)).

As for bottled water, it is first important to know that 25 to 30 percent of it comes straight from municipal tap water systems. Some of that water goes through additional filtering, but some does not. NRDC has extensively researched bottled water and has found that it is subject to less rigorous testing and purity standards than city tap water.

The fact of the matter is that some people might prefer bottled water from a taste or convenience perspective, however, tasting better is not the same as being healthier or purer.

Expert answer by: Andrea Ruman, MD, an internist and assistant clinical professor of medicine at UCLA. Read more answers to this question, or ask your own.

This article originally appeared on ChickRx