Almost one in three people drink fewer than the six glasses of water or other liquid a day doctors recommend, a Department of Health survey shows. In a behavioural risk factor survey conducted in April and May, the department asked more than 2,000 adults how much liquid they drink each day. Of the respondents, 32.3 per cent said they drank an average of fewer than six glasses of liquid per day, results released yesterday show. The average person needs six to eight glasses of liquid per day. While some people, such as sportsmen and breastfeeding mothers, may need more liquid, those with heart and kidney problems may require less, according to the department. Common signs of dehydration include thirst, dryness of eyes, lips and nasal passages, tiredness, increased breathing and heart rate, irritability and difficulty in concentration. The department said although many people took in their daily fluids in the form of water and other beverages such as juices, alcohol and soft drinks, taking too many drinks with high sugar levels could be detrimental to health. The survey report broke down the responses by age and sex. It found: 32.8 per cent of men admitted they drank fewer than six glasses of fluids daily, while 31.9 per cent of women said they failed to reach that benchmark; Those aged 18 to 24 and 55 to 64 drank the least water - 34.6 per cent of respondents in each category said they drink less than they should; Of those in the 35 to 44 age group, 33.5 per cent drank less than their bodies required; and Just over 30 per cent of people in the 25 to 34 and 45 to 54 age groups also drank less than six glasses a day. Managers, administrators and professionals on average drank more liquid than manual workers, the survey found. Unemployed respondents, of whom only 32.8 per cent drank less than six glasses; managers, only 27.5 per cent of whom failed to reach the benchmark; and professionals, of whom only 24.2 per cent drank less than required, were the best at following doctors' orders, the survey found.