Purpose of reviewThe intake of water and electrolytes is inseparable from the ingestion of nutrients by normal or artificial means. Recent reports have agreed in criticizing the poor standards of practice and of training in the management of fluid and electrolyte balance, resulting in a large amount of avoidable morbidity, particularly in the elderly who are more vulnerable to fluctuations in body composition.Recent findingsAgeing is associated with impaired physiological reserve and a reduced ability to compensate for fluctuations in environmental conditions. These changes include reduced cardiac and renal reserve, making the elderly more vulnerable to changes in water and electrolyte gain or loss with a resulting increase in morbidity and mortality. The ability to cope with errors in prescriptions is correspondingly diminished. Dehydration is a common problem in nursing homes and in the community, due often to failures in detection and appropriate management. In many cases, the cause is iatrogenic due to diuretics or drugs which impair the intake of food and fluid. Salt and water overload, particularly in hospital patients, is also common and results in impaired recovery from surgery and increased perioperative mortality and morbidity. Hyponatraemia is also an important clinical problem in hospital and the community.SummaryBetter training in the detection, prevention and management of fluid and electrolyte imbalance is needed to reduce common and serious morbidity associated with this problem to which the elderly are especially prone, owing to their diminished physiological reserves and increased comorbidity.