A metering device was developed to introduce benzene, toluene, xylene, and 1,2,4 trimethylbenzene vapors into water using air as a carrier gas. Setting the carrier gas flows for the respective aromatics at 10, 25, 120, and 500 cm3/min for 2 h resulted in concentrations of 8.2, 13.0, 12.0, and 7.2 μl/liter, respectively, in 4 liters of water. The aromatic concentrations were maintained in a static system by bubbling air through the water, and in a continuous flow system by replenishing the water. In static systems the respective aromatic concentrations were maintained for 4 days within the ranges of 13–14, 5.1–7.0, 0.40–0.50, and 0.018–0.028 μl/liter by bubbling the aromatics into the water at 5 cm3/min and independently aerating the water at 100 cm3/min. In a 14-day continuous flow system benzene concentrations ranged from 2.1–2.8 μl/liter when benzene was bubbling at 23 cm3/min and water was flowing at 1.8 liters/min.