Director of nutrition for WebMD Kathleen M. Zelman explains that drinking water has several benefits, including maintaining a balance of bodily fluids, controlling calories, energizing the muscles, keeping the skin looking good, helping the kidneys and maintaining a healthy bowel function. However, Glasgow-based general practitioner Margaret McCartney in a MailOnline.com article warns against drinking too much water, stating that drinking water when not thirsty may impair concentration.
Zelman also states that the old guideline of drinking eight glasses of water a day has no scientific basis but drinking water plain or as part of other fluids still has benefits, such as preventing dehydration from fluid loss. Yet, McCartney also warns that drinking excessive amounts of water leads to hyponatremia, a rare but potentially fatal condition in which the body’s salt levels drop and potentially lead to swelling of the brain.
In addition to McCartney's findings, MailOnline.com reports on other studies that show harmful effects of water, including causing kidney damage rather than preventing it. Excessively drinking water may also disrupt sleep by causing frequent urination. On the other hand, the resource also lists several other benefits of drinking water, such as preventing headaches and fainting from dehydration and keeping the skin moisturized.