“Children don’t need as much toxicant for it to cause a lot of harm,” says Abby Mutic, a nurse researcher in environmental health at Emory University. “They don’t metabolize things in the same way, and their brains and bodies are still developing.” On the whole, most kids — and most adults, for that matter — don’t drink enough water, and water is the healthiest thing to drink, says Maria Galvez, associate professor in the departments of environmental medicine and public health and the department of pediatrics at the Icahn School of Medicine at Mount Sinai. That’s why a trustworthy water supply is so important. Kids between the age of 1 and 3 are supposed to drink around five cups of water a day, and it’s not something they can skip because of worries about water supply. This is why it is especially scary to think something you give your child to drink that is supposed to be good for them might be unhealthy. But there are measures families can take to protect themselves.

Contaminated Water: What to Worry About

Risks of water contamination vary widely across the United States, says Mark Miller, co-director of the Western States Pediatric Environmental Health Specialty Unit at the University of California, San Francisco. “It depends on location and the specific circumstances.” But some relatively common pollutants are concerns across the country. For very young children, nitrates are especially dangerous. Nitrates can leak into the water supply from sewage and fertilizer, and levels of the compound over 10 milligrams per liter can lead to a condition called methemolobinemia, but often referred to as “Blue Baby Syndrome,” in infants younger than a year old. The condition prevents red blood cells from effectively carrying oxygen, and can lead to lethargy, difficulty breathing, and in extreme cases, loss of consciousness and death. “For environmental health, that is a problem unique to children,” Miller says. Arsenic, which is a carcinogen, poses a health risk to both children and adults, and even levels that are permitted in drinking water have been linked to cancer, Miller says. “Being above the maximum contaminant levels for that is a pretty significant thing.” Lead, which impairs cognitive development in children, can contaminate water if it leaches out from metal pumps or pipes. Even low doses can impact children — causing a constellation of symptoms including developmental delays, irritability, learning difficulties, hearing loss. Lead exposure in childhood is also linked to violent crime. While some places do have serious contamination from chemicals like lead and nitrates that can cause direct health effects, the average individual risk of illness from water is low, Miller says. “These issues are largely not going to cause something you’d be able to identify as a direct result of water in your child,” he says. Zooming out, though, is when you might start to see problems. “The impact on any one child might be small, but because we all drink water every day, the overall impact on the public might be more significant.” According to the 2017 analysis by the National Resources Defense Council found that over 300 public water systems had lead levels higher than health standards, for example, and over 1,000 had arsenic levels higher than health standards. There are, of course, contaminants beyond lead, arsenic, and nitrates. Manganese and a variety of chemicals that come from pesticides are concerning, but these are much rarer and when found, at least in public water, usually in such low doses as to not be harmful. Bacteria, viruses, and protozoa all are especially harmful to kids — but are exceedingly rare in public water supplies. If you’re out backpacking with kids, on the other hand, filter your water and bring iodine!

Is Your Water Contaminated? How to Find Out

The first step towards ensuring that your water is safe is knowing where your water comes from, Galvez says. “Do you have town water, or well water?” she says. “Know your water supply.” If your water comes from a well, it isn’t subject to federal regulations. About 15 to 20 percent of people in the United States get water from wells, and they’re responsible for monitoring their water for themselves. Most water-related disease outbreaks come from well water, but many people just test wells once when they move into a home, Galvez says. The American Academy of Pediatrics recommends that wells be tested annually for nitrates and coliform bacteria, which are a sign of fecal contamination. If there’s a newborn baby in the home, the water should be tested again, even if the annual test was clear. Well water should also be tested if the well itself is disturbed or damaged, if multiple people in the same home come down with a gastrointestinal illness. Children considered at risk for lead poisoning (who are eligible for Medicaid, or live in a house built before a certain year) are screened for elevated lead levels at 1 and 2 years of age, and if a child has elevated levels of lead in their blood, water should be tested again as well. Many towns also have free lead testing kits available if you have questions about the specific pipes in your home — even if water is lead-free at the source, metal components in the home may contain it. If that’s not an option, Galvez says, you can purchase kits. If you drink community or town water, on the other hand, the water provider is required by law to produce a public, annual water quality report to show if the water meets the federal standards for contaminant levels. “Check out the report. See what your town is doing. Check out water quality report. If you’re concerned, let local decision-makers know you’re concerned,” Galvez says. The Environmental Protection Agency website can direct you to your local water supplier.

Contaminated Water, in a Bottle?

Barring signs of major contamination, though, low-level water worry shouldn’t push people to run to bottled water. Doing so won’t necessarily help. “Bottled water is not regulated more stringently than tap water,” Miller says. “We don’t want people spending fortunes on it. That’s not the case if there’s truly severe local contamination, but with public water systems meeting standards, you’re not necessarily better off with bottled water.” Bottled water is also expensive — in Flint, Michigan, where severe contamination meant residents had to use bottled water, keeping the town supplied cost over $20,000 a day — and creates plastic waste. For example, high arsenic levels have been found in brands of bottled water, including brands sold at Whole Foods and Walmart. Water filters, though, are often an easy way to protect against contaminants. “I don’t think you can be overly cautious about these things” Mutic says. “There are water filtering systems that are not cost-prohibitive for families.” For between $40 and $150, parents can outfit their faucets and sinks with NSF International-certified filters that can reduce contaminants that might still be in the water supply — which, for some families, might be a small price for peace of mind. “I don’t say this to create alarm, and worry,” Mutic says. “I encourage people to have more knowledge about their water so they can be empowered.”