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DEAR DR ROACH: Can you please explain to me what has changed over the years in regard to dehydration? I never remember my parents carrying bottles of water to work, and we definitely never had the ease of a disposable water bottle to carry with us wherever we went. I can’t even imagine what consequences we’d have faced if we carried a cup of water to put on our desks at school. We had to wait until recess! If we drank water at home, it was usually out of the hose in the backyard while on the go. Yet, I never remember dehydration even being worried about or discussed back in the day.
Nowadays, everything is about drinking water. We have disposable plastic bottles, refillable stainless-steel water bottles, flavored waters, and numerous variations of H2O. I carry water in my purse and in my car, and I never leave home without it for fear of dehydration. I understand that water is healthy and our bodies require it. But I had the same body 60-70 years ago, and it was apparently fueled with milk per my parents’ orders! Any insight? -- M.B.
ANSWER: Dehydration (a lack of free water) and volume depletion (a lack of water and salt) were problems back in the day, but it’s mostly that there’s a lot more attention to them now. However, I think that more people are being physically active outside than before. (There were far fewer runners and cyclists in the ’60s and ’70s than now.) Additionally, temperatures are both generally warmer and more extreme than they were decades ago.
Still, I see more people with water excess than dehydration now, and I think that we’re more worried about it than we need to be. (There are certainly exceptions, like people who work or exercise outdoors in heat. People who are outdoors for extended periods, such as hikers, need to carry adequate water.)
Thirst is a good way of determining whether you need to drink water, with some caveats. One is that cooler but drier climates -- especially at a higher altitude -- can cause you to lose more water than you think. If you aren’t listening to your body, you can get dangerously dry. The second is that the thirst sensation can be diminished in older people.
Water is the most effective way to stay hydrated, but milk is mostly free water as well. It just has protein, sugar and (depending on the type) some fat that you may not want if all you’re looking for is to hydrate.
DEAR DR. ROACH: My husband is 79 years old. In 2012, he had a total knee replacement due to the absence of cartilage, causing bone-on-bone arthritis at the joint. He experiences pain in this knee when he walks. No pain relievers work. Is there anything that can be done to stop the pain? He needs to get more exercise for his heart health but can’t walk very far due to the pain. -- S.S.
ANSWER: Pain in a knee after a total knee replacement makes me worried about the loosening of the prosthesis in the bone. The prosthesis may also become unstable. His next visit should be to the knee surgeon, who will get imaging of the knee.
An infection is unlikely so far out of surgery but needs to be considered. Knee pain can sometimes feel like it’s coming from the hip, so this could mean the possibility of a hip X-ray or a CT scan if an evaluation doesn’t show a problem with the artificial knee joint. People with knee arthritis often have it in the hip as well.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu. (c) 2026 North America Syndicate Inc.
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