THERE is little doubt that an individual's performance, whether at work or play, can be impaired by dehydration, and a loss of even just two per cent of body mass has the ability to affect physical and cognitive performance. Installing a water cooler encourages staff to stay hydrated, as well as giving a professional impression to clients and other visitors to the practice when you offer them refreshments. The average British worker drinks around five cups of tea or coffee daily, that_s 48,000 cups of caffeinated liquid during their working life. Surveys have found that nearly six out of 10 people (58 per cent) do so out of habit; although a quarter of those don't drink caffeinated beverages at home. There_s nothing wrong with the occasional cup of coffee or the odd soft drink, but employers have a duty of care to encourage healthy hydration; and water is also kind to teeth and calorie free. Even small levels of dehydration can create headaches, lethargy, or just an overall lack of alertness. And in the long-term it can create problems with the renal system and mental functioning, as well as cardiovascular and digestive systems. Office managers should be aware that the Workplace (Health, Safety & Welfare) Regulations 1992 state that an "adequate supply of wholesome drinking water" must be provided, and that it be readily available at suitable and clearly marked places. A water cooler is one of the best means of providing healthy hydration. Whether this is a plumbed-in (mains fed) unit or a bottled water cooler will depend on your firm_s particular circumstances. If there is access to plumbing but limited storage space, a mains-fed cooler is the best option; however, a bottled water dispenser is the best choice if you want to offer drinks in the heart of the offices or in a boardroom. Here are some tips you could give to colleagues on how to stay sharp and alert: