The Dutch water companies have commissioned an ambitious 4 year research programme in pursuit of an impeccable drinking water quality, called Quality 21 (Quality for the 21st century). The Dutch approach has always been to safeguard drinking water quality from source to tap by excellent design, operation and research. This drinking water is generally distributed without a disinfectant residual. The Dutch consumers appreciate this concept and have a high confidence in the quality of tap water. The new research programme aims at providing the scientific foundation for future decisions on quality goals and the advantages and limitations of modern water treatment technology, such as membrane filtration and UV/AOP. The goals are to achieve a robust and reliable drinking water infrastructure that will guarantee an impeccable water quality at the tap at all times, also in the future when new threats may emerge. The programme includes studies on water quality goals and total system approach, and experimental research into water treatment, biological stability and (the prevention of) quality deterioration in the distribution network. Important focal points in the research will be the prevention of microbiological problems (including Legionella) in the network and in building installations, the prevention of problems with organic micropollutants such as NDMA, EDCs and pharmaceuticals and the advantages of reducing particles and sediment in the distribution network. The programme will be coordinated by Kiwa Water Research and will be carried out with the water supply companies and in cooperation with universities and other research institutes including the partners of the Global Water Research Coalition.