Until recently most interest in drinking water quality has been in the finished water as it leaves the treatment plant. The Safe Drinking Water requires that MCLs be met at the consumers tap. Because finished water may undergo substantial changes while being transported through the distribution system to the consumer, interest has increased on the effect the system itself may have on water quality. The paper reports on a study that was conducted in cooperation with the North Penn Water Authority in Lansdale, Pennsylvania to study the effects that hydraulic behavior may have on contaminant propagation in the system. The study demonstrates that water quality varies not only with time but with space as well. Methods for continuous monitoring were evaluated as part of the study. Several different types of models were also developed in order to provide a framework for studying contaminant propagation.