In hot water

Dear Lucy: A certain member of my family uses hot water for everything—rinsing chicken, washing vegetables, and even brushing teeth. I have heard that hot water should not be used for things like this. Can you please clarify? —Cool Cat

Illustration of a bathroom sink with water and question marks coming out of the tap


Dear Kitty: Thank you for an interesting question! Lucy has often wondered if there is any legitimate rationale for the oft-repeated warning against ingesting hot water. Your question gave her a reason to search out the truth.

Lucy’s quest led her to Dr. David V. Diamond, a primary care provider at MIT Medical and member of MIT’s Environmental Health and Safety Team. Diamond tells Lucy that this warning is based on concerns that hot water, which dissolves contaminants more readily than cold, might contain trace amounts of metals, particularly lead. 

“Some older homes have lead water pipes, copper pipes with lead solder, or plumbing fixtures that contain lead,” he explains, noting that the use of such materials was prohibited by federal law after 1986. “If a house happens to have lead in the piping,” he continues, “small amounts can leach into standing water in pipes or in a hot-water tank.” 

However, Diamond explains, the lead concentration, if any, will quickly decrease as water runs and standing water is flushed from pipes. “So,” he says, “even if your ‘certain family member’ lives in a home with lead piping, they can largely eliminate any risk by running the hot or cold tap water for two to three minutes before use.”

Diamond also assures Lucy that no Massachusetts community is likely to face a water crisis like the one in Flint, Michigan. “Municipal water supplies in the state are regularly checked for lead,” he explains, “and no contaminations in city water supplies have been found.” 

While your family member’s hot water use may not pose much risk—particularly if they let the water run for a few minutes first—Diamond reminds readers that the risk of lead exposure is real and poses a particular danger to young children and pregnant women. “The greatest risk comes from exposure to lead-containing paint chips or dust,” he notes. Other potential sources of exposure include toys and jewelry, folk medicines, fumes from recreational gun use, dust from old artificial turf, and foods grown in contaminated soil. “A simple blood test can measure lead exposure,” he adds. “If the results show elevated levels, treatment and exposure-control actions can occur. The CDC website is a reliable source of information on the dangers of lead exposure.”

Lucy also reminds her readers that members of the Institute community can turn to MIT’s Environmental Health and Safety Office for answers to questions or concerns about their drinking water or any other aspect of their environments at work or at home. —Lucy

Back to Ask Lucy Information contained in Ask Lucy is intended solely for general educational purposes and is not intended as professional medical advice related to individual situations. Always obtain the advice of a qualified healthcare professional if you need medical diagnosis, advice, or treatment. Never disregard medical advice you have received, nor delay getting such advice, because of something you read in this column.