Is It 100% Safe to Drink Tap Water? Here's the Truth
Woman filling up glass with tap water out of sink faucet
Staying hydrated is a tried and true tip for staying focused and healthy. But how much does your water source matter? More specifically, is tap water safe to drink? If you just refilled your Stanley with sink water for the second time today, the good news is that in general, the answer is yes.
"Tap water in the U.S. is usually very safe," says Dr. Linda Yancey, MD, the director of infection prevention at the Memorial Hermann Health System in Houston. "We have one of the most advanced water systems in the world, but untreated tap water is not the best choice for some."
Indeed, a 2021-published CDC report pointed out that tap water isn't sterile, and using it in home medical devices can lead to infections because of waterborne pathogens.
Say what? If it isn't sterile, is sink water safe to drink or not? Here's the 4-1-1 on H2O straight from the tap.
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When Tap Water Isn't Safe to Drink
So, is it safe to drink tap water? Here's the truth: It probably is. However, it's not always the best idea to drink it, and Dr. Yancey suggests avoiding tap water in some instances. "Tap water should not be used in continuous positive pressure (CPAP) machines, for nasal irrigation or neti pots, in humidifiers, for cleaning contact lenses or to clean open wounds," Dr. Yancey explains.
Dr. Rianna Murray, Ph.D., an assistant research professor at University of Maryland, also recommends against using tap water to prepare infant formula. The CDC says that the youngest among us and older adults are more at risk of becoming ill because of the bacteria floating around in tap water.
"People with weakened or developing immune systems are at the highest risk for infection or illness from microbially contaminated water," says Jill Stuber, a food safety consultant and coach at Catalyst LLC.
Dr. Yancey adds that tap water has small amounts of microbes, like bacteria and ameba. Before you write off drinking it, keep this in mind.
"Our body has defenses against these organisms like the acid in our stomachs and the robust immune protection in the GI tract," Dr. Yancey says. "But when we use tap water in ways that bypass these protections, it can cause trouble. In CPAP machines and humidifiers, the water goes directly into the lungs and can cause pneumonia. For nasal irrigation, there is a small risk of an amebic infection because the water comes into contact with nerves that go straight to the brain."
It's also not a great idea to use tap water when putting in, taking out or cleaning your contact lenses. "Certain eye infections can be caused by using untreated tap water on them," Dr. Yancey shares. "It is better to use specially made and sterilized commercial contact lens solution. In open wounds, you have direct contact with deeper tissue that is usually protected by the skin."
The CDC indicates that pathogens found in tap water like Pseudomonas and Ralstonia pickettii can contribute to hospitalizations or death (in rare cases). Acanthamoeba is also in tap water, which can cause an eye infection that leads to blindness, the CDC reports. Remember, though, this is very rare, and shouldn't dissuade you from using tap water unless you are very immune-compromised.
While it's generally safe for adults to consume tap water, babies are less equipped to handle potential risks, so it's never a good idea to use tap water when mixing infant formula. "Babies are more vulnerable to certain contaminants like nitrates or lead," Dr. Murray explains. "Using tap water that is contaminated with these substances when preparing formula can pose health risks for babies. Babies exposed to excess nitrates in tap water can develop methemoglobinemia, also known as 'Blue Baby Syndrome.'"
Dr. Murray says this can lead to health and development issues.
Related: This Is the #1 Sign that You’re Drinking Enough Water, According to a Primary Care Physician
Why Many Americans Are Unaware of Tap Water Risks
In a CDC survey conducted in August of 2021, about 1 in 3 Americans were unaware that tap water contained living organisms like bacteria. Moreover, about a quarter reported using tap water in humidifiers and CPAP machines.
"Many people assume that tap water is inherently safe due to stringent regulations and monitoring by water utilities," Dr. Murray says. "Many people trust that regulatory agencies such as the EPA are effectively monitoring and addressing water quality issues."
Tap water quality also varies. "People in regions with consistently good water quality might be less aware of the potential risks and may perceive water contamination as a problem that primarily affects other regions or communities," Dr. Murray explains. "In some cases, language barriers may prevent people from understanding available information about water quality in their area, limiting their awareness of potential risks."
Keep an eye out for local health advisories. "If your local health officials issue a boil water advisory, it's crucial to boil tap water before using it for any purpose," Dr. Murray says.
Yes, drinking is included.
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How to Make Tap Water Safer
Tap water is generally safe for most people to drink, but how can you make it both safer for immune-compromised people to drink and safer for at-home uses?
1. Boil water
One of the most straightforward ways to increase tap water's safety is by boiling it.
"Just bring the water to a boil for one minute and then let it cool before use," Dr. Yancey says. "Cooled boiled tap water can be safely used in nasal irrigation and the other situations discussed above. It is also safe to make infant formula for babies with delicate immune systems or who are under two months of age."
2. Use a reliable water filter
Ensure it's certified to remove contaminants like lead, chlorine and bacteria, Dr. Murray advises. "Ensure the filter is regularly replaced according to the manufacturer's recommendations," she says.
3. Flag changes
It may not just be you. "Pay attention to any changes in the taste, odor or appearance of your tap water," Dr. Murray says. "If you notice any unusual changes in your tap water or have concerns about its safety, report them promptly to your water utility."
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4. Do your homework
If you're concerned about how safe tap water is to drink, you can check for yourself. "If you are on a municipal water supply, the U.S. Environmental Protection Agency requires them to provide a yearly Drinking Water Quality Report that you can view on their websites," Dr. Yancey explains.
5. Lean on other resources
Some detective work can also help you determine whether your water is best positioned for safety—but call an expert.
"If you are concerned about the pipes in your house, they can be inspected by a plumber to make sure there are no issues," Dr. Yancey shares. "If you are on well water, you can arrange for an inspection of your system to be sure that it is safe and up to code."
Next up: The One Thing You Should Never, Ever Do If You Have Heart Palpitations
Expert Sources
Dr. Linda Yancey, MD, the director of infection prevention at the Memorial Hermann Health System in Houston
(Mis)perception and Use of Unsterile Water in Home Medical Devices, Emerging Infectious Diseases.
Water Contamination and Diseases. CDC.
Dr. Rianna Murray, Ph.D., of University of Maryland, also recommends against using tap water to prepare infant formula
Jill Stuber, a food safety consultant & coach at Catalyst LLC
Acanthamoeba Keratitis FAQs. CDC.
