Experiments were conducted in a pilot-scale water distributiondead end pipe system to define relationships between chlorine residual concentrations and system variables. These variables included flow rate, biomass concentration and biofilm density, and chlorine concentrations. The experimental apparatus is a prototype of a dead-end distribution pipe. Hydraulic dispersionand chlorine concentrations in this system were studied under various flow conditions. Fluoride was used as a tracer to estimate chlorine dispersion coefficients as a function of Reynolds number. Includes reference, figures.