Have you ever wondered what contaminants are lurking in your tap water? It’s easy enough to find out from your water company.

Every community water supplier is obligated provide an annual report, often called a Consumer Confidence Report, to its customers. The report provides data on water quality, including contaminants. The Environmental Protection Agency (EPA) offers tips on how to get your local CCR report. From there, you can figure out whether you might want to buy a water filter and what kind of filter to buy.

Related: Is It Safe to Drink the Water on a Plane?

But what if you turn on the tap one day and your drinking water has a brownish tinge or a sulfur-like smell? Does it mean the water isn’t safe to drink?

A change in your water’s color, smell or taste is not necessarily a health concern, the Centers for Disease Control and Prevention (CDC) says, but you should notify your water company anyway because it could indicate a problem.

Take the example of Flint, Michigan. Residents there noticed a change in the color and taste of their water in April 2014, after the city changed the source from the Detroit water system to the Flint River. Many months later came reports of lead in the drinking water and children with high levels of lead in their blood.

More recently, officials in Genesee County, which includes Flint, revealed an increase in the number of deaths due to Legionnaires' disease, which may also be tied to water quality, Fox News reports.

Legionnaires' is a type of pneumonia caused by inhaling mist infected with Legionella bacteria. Sources may include cooling towers (part of the air conditioning system in large buildings), hot tubs and hot water tanks. Less commonly, says the CDC, it can be transmitted “via aspiration of drinking water, which is when water ‘goes down the wrong pipe,’ into the trachea (windpipe) and lungs instead of down the digestive tract.”

One small study in 2014 tested 78 public and private water taps, including kitchen sink taps, and found traces in Legionella in almost half of them.

The best way to prevent Legionnaires' disease is to maintain water systems in which the bacteria can grow, according to the CDC.

Related: How to Clean Water While Traveling Abroad

What’s in your water?

The Environmental Protection Agency is responsible for making sure public water supplies in the United States are safe, and the CDC says the United States has some of the safest drinking water in the world. But contaminants can be introduced from sources such as:

  • Naturally occurring chemicals and minerals (radon, arsenic, uranium)
  • Local land use practices (fertilizers, pesticides)
  • Manufacturing processes
  • Sewer overflows

The EPA makes sure high levels of these contaminants, which pose a health risk to humans, are not in our water. The EPA also tests water for more than 90 different contaminants, including E.coli and salmonella, in public drinking water.

If you want to test your water yourself, contact your state drinking water certification officer to get a list of certified labs in your area. The price of the test varies from $15 to hundreds of dollars, depending how many chemicals you want to test for.

If the water in your community isn’t up to EPA standards, your public water system may issue a boil water advisory, as they did in Flint. If a boil water advisory goes into effect in your community, follow it. But keep in mind that while boiling water will kill off bacteria and parasites, it won’t get rid of lead. If there’s too much lead in the water, bottled water is the answer.

According to the CDC, you should take action to minimize your lead exposure if your tap water contains more than 15 ppb (parts per billion). Find out more from the CDC’s page on lead in water.

The CDC advises drinking only cold water out of the tap. Warm water is much more likely to contain unsafe levels of lead.

Related: 5 Ways to Avoid Lead Poisoning in Kids

Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for Boston.com at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.