Is It Safe to Cook with Hot Water from the Tap?

Stop me if you’ve heard this one before: It’s bad to cook with hot water from your faucet. Many home cooks—myself and other The Spruce Eats staffers—have spent years of our lives cooking with this piece of kitchen wisdom in the backs of our minds. 

The reason why you don’t use hot water for cooking may be different based on where you grew up or who taught you to cook. Somewhere along my culinary-school-to-restaurant journey, I was told that hot tap water can taste funny, and will affect the flavor of your meal. Others avoid it because lead is more likely to leach into the water when it’s hot. Or maybe you’re part of the faction that doesn’t really know why you’re supposed to avoid cooking with hot water. (“The chemicals?” one of my colleagues guessed as we discussed this.)

Weird-tasting soup is one thing, but a dinner that’s potentially dangerous is entirely another matter. With such high stakes, it is imperative to get the facts. So is it actually unsafe to drink or cook with hot water from the faucet? After talking with drinking water experts, I learned the answer is: Yes. It is unsafe to consume hot tap water.

Why It’s Unsafe to Drink Hot Tap Water

My research first brought me to the Environmental Protection Agency, which lays down the law pretty clearly in a Q&A on its website: “Never use water from the hot water tap for drinking, cooking, or making baby formula,” the EPA says. The CDC confirms this. “Do not cook with, or drink water from the hot water tap,” Jasen Kunz of the CDC’s Domestic Water, Sanitation, and Hygiene (WASH) Epidemiology Team, told me over email. To get into the specifics of why hot tap water is so dangerous, I contacted Ben Montross, the Drinking Water Program Manager for the state of Vermont, where I live. 

Montross confirmed my preliminary findings: It is potentially dangerous to drink, cook with, or make coffee or tea with hot tap water. He cited some high school chemistry wisdom as a top-line explanation: “If you want to speed up a reaction, apply heat.” In other words, warm water is more likely than cold water to pull minerals, metals, and contaminants from boilers, hot water tanks, and pipes. Benign minerals, like calcium, can affect the flavor of your water. Hazardous materials—namely lead—can be seriously harmful, especially to children. The CDC lists brain and nervous system damage, slowed growth and development, learning and behavior problems, and hearing and speech problems as results of lead exposure.  

At this point, you may be thinking what I was: “Wait—aren’t modern pipes lead free?” Montross explained that it’s a little more complicated than that. Even newly-manufactured pipes have a permissible amount of lead in them: 0.25% is allowable according to the Safe Drinking Water Act (SDWA). Pipes dating back to the 1980s can have as much as 8% lead, and pipes from the 1950s may contain as much as 50% lead. As Montross explained, adding lead to pipes protects them from cracking and bursting in freezing temperatures, because lead is more malleable than the other materials used, like brass. That’s why it’s still used.

Many homes and dwellings have older pipes, but even if your plumbing is brand new, that small amount of lead carries a risk. And it’s not just lead: Montross explained that hot water heaters provide a more hospitable environment to bacterial growth, so consuming hot water straight from the taps presents a greater potential for exposure to harmful bacteria. “Germs especially like to live and grow in water when it is stagnant (not flowing) or when it is not treated with enough water treatment chemicals, such as chlorine,” confirmed Kunz. The CDC says that boiling water for one minute (or three minutes at elevations higher than 6,500 feet) will kill bacteria. However, boiling water does not remove lead.

To consume tap water with the lowest possible risk of contaminants or detrimental health issues, Montross says it is recommended to only consume cold tap water. He also points out that the water sitting in pipes of any age carries a greater potential for contamination, so it’s good practice to flush the taps until the water runs truly cold before consuming it. We should also regularly clean and sanitize appliances that use water, like humidifiers. Homeowners can mitigate (but not entirely eliminate) their risk by updating the plumbing in their HVAC systems. Tenants are encouraged to communicate with their landlords and property managers about preventing waterborne illness and disease. But no matter where you live, the best way to protect yourself from contaminated water is to drink cold tap water, not hot.