The Region of Peel has embarked on a major investment in its drinking water infrastructure to respond to increasingly stringent regulations and increasing water demands, the latter as a result of increased growth and an agreement to supply water to an adjacent municipality, York Region. The Lakeview Water Treatment Plant (WTP), currently rated at 560 ML/d, will be expanded to 820 ML/d by 2006 and treats surface water from Lake Ontario. Water quality challenges of the source water include enhanced pathogenic risk due to the intake's proximity to a wastewater treatment plant, periodic taste and odor episodes, intermittent elevated turbidity events of short duration, fluctuations in water quality not normally experienced on Lake Ontario, and long residence times as the water travels from the Lakeview WTP to York Region. In general, the source water can be described as a low turbidity, low color, and moderate alkalinity water, laden with low to moderate levels of organic carbon. Expanding the Lakeview WTP created an opportunity for the Region to re-visit the treatment objectives at its surface water facilities, and a commitment was made to enhance treatment to meet and exceed the requirements of the Ontario Drinking Water Standards. Includes tables, figures.