Nickel analyses of tap water from several sources in Copenhagen gave up to 490 X 10(-6) g X 1(-1) in the first 250 ml portions. Hot water gave higher values than cold water. After flushing for 5 min, low values were found. Considerable variation from time to time and from tap to tap was found. Drinking of only the first portion in the morning might have an influence on nickel hand eczema.