Ground water contain natural radioactivity associated with uranium and thorium that present naturally in rocks and soils. Humans may be exposed to the emission of energetic alpha particle from supported radon decaying process in this water when it is inhaled or ingested. Assessment of supported radon in ground water was carried out using fourteen ground water samples from Cameron Highlands. The measurement was accomplished by degassing the water samples using pump and then allowing the gas to flow into specially constructed 0.0191 m8 metal chamber. The activity concentration of supported radon in water sample was measured using continuous radon monitor inside the radon chamber. Measurement was carried out at one hour interval for twenty four hours. The hourly supported radon concentration was found to stabilize after about 8 hours. The stabilized concentration was used to determine supported radon activity concentration in the water samples. Results of the study show that depending on the sampling location, the activity concentrations of supported radon are in the range from 0.09 - 0.48 Bq/L which is lower than the activity concentration of radon in drinking water as proposed by USEPA (11 Bq/L).