Some consumers prefer drinking bottled water over tap water because they believe bottled water to be cleaner, but this is a common misconception. Tap water processed by water treatment plants is actually subject to far more stringent quality control standards than the bottled water sold in stores.
According to the Natural Resources Defense Council, tap water must be tested 100 times every month for fecal bacteria and must be cleansed of known carcinogens. The certification processes for the technicians who perform testing and filtration are very strict, and any violations of water purity standards are required by law to be publicly reported.
Still, even with all that testing, there are ways that certain impurities can get into your household water supply. Some of these indicate possible problems with your local water authority's pipes and equipment, while others are problems that you must address as a homeowner.
It took a herculean effort to build North America's massive plumbing infrastructure, but the effort to maintain that system is just as daunting. Water mains and municipal pipes get older every day, and in the cases of some of our oldest cities, they're starting to decay. When water mains break, the age of the system is often a factor, and these breaks can introduce impurities into your household tap water.
What is in tap water that contains impurities? In cases of water main breaks, the main impurity is often dirt. Even when municipal water mains and pipes remain intact, they can leach rust into the water supply if they've started to corrode. In small amounts, rust is harmless -- but it's a sign of bigger problems to come.
Depending on where your water is naturally sourced, you may also find small flecks of iron or manganese coming from your tap. Fortunately, these don't pose a health hazard. But they can affect the taste of your water, and they can discolor dishes and clothing with regular washing.
Some events can lead to harmful chemicals found in tap water. Notably, the Flint water crisis resulted in high levels of lead being distributed throughout Flint, Michigan’s water supply due to a combination of errors and oversights: the water source was switched to a more corrosive water system, the anti-corrosion agents used were insufficient, and aging lead pipes were still in place. Human error was a key factor in the Flint water crisis, and the challenges of corrosive water and aging lead water lines are typically faced responsibly by municipalities from coast to coast. The water treatment technologies in place throughout most of the United States effectively employ drinking water additives to reduce waterborne chemicals, parasites, bacteria and viruses to safe levels.
Fortunately, there are several actions you can take if you discover any suspicious impurities in your water supply. Most hardware stores sell simple water testing kits you can use to determine what's in your water, but if you want a more thorough test, you should call a licensed plumber.
If the contaminant is dirt, this is most often due to a water main break. You need to contact your local water authority to report this problem. If it's rust, it could be coming either from your water authority's equipment or from your own. A plumber can help you find the source.
For iron or manganese, a water softening system will usually help keep your water tasting fresh and prevent it from causing stains. And if you want the ultimate in worry-free home filtration, consider installing a reverse osmosis system. These systems filter out most impurities at the point where water flows into your home, making faucet and pitcher filtration systems unnecessary.