AWWA JAW62683

Pressure control can be an effective way to reduce leakage in water distribution systems. The authors present results from a laboratory study conducted to determine the relative importance of soil versus orifice head loss in controlling leakage rates and to determine an appropriate equation to define this flow. The study demonstrated that the nature of the leak reduction could be described by a dimensionless orifice/soil (OS) head loss number. In most leaks, head loss through orifices is more important than head loss through soil. For high OS number values, orifice head loss dominates; for low values, soil head loss dominates. In most real-world cases, the OS number is large so that modeling leakage with flow emitters (orifice equation) is appropriate. Computer models may also be useful in evaluating the effectiveness of pressure-reduction schemes for reducing leakage. However, controlling pressure does not only reduce leakage volumes, it also can have an effect on service pressure for customers. Thus it is important to determine the effect of any change on customer pressure before pressure control is introduced. Using a hydraulic model of the system, a utility manager can determine the effect of pressure reduction on both leakage and customer pressures. Includes 16 references, figures.