When designing water-distribution systems, the engineer needs to consider economic and technical factors, such as acquisition of property, construction costs, site topography, and geological conditions. In addition, emergency flow-control scenarios should be analyzed and tested during the design phase, since they affect the piping system design and the specification of surge-protection equipment.

Pipeline layouts with undulating topographic profiles are common. For these systems, it may be desirable to change the route and/or profile of the pipeline to avoid high points that are prone to air accumulation or exposure to low pressures (or both), but this is seldom possible. If the minimum transient head is above the elevation of the piping system, then transient protection devices are most likely unnecessary, thus minimizing construction costs and operational risks.

Low-head systems are more prone to experience transient vacuum conditions and liquid-column separation than are high-head systems. If the system designer does not account for the occurrence of low transient pressures in low-head systems, then a pipeline with inadequate wall thickness may be specified, potentially leading to pipeline collapse even if the pipeline is buried in a well-compacted trench. For example, low-head systems with buried steel pipelines and diameter/thickness ratios (D/e) more than 200 should be avoided because of the risk of structural collapse during a transient vacuum condition, particularly if the trench fill is poorly compacted.

Steel, PVC, HDPE, and thin-wall ductile-iron pipes are susceptible to collapse due to vapor separation, but any pipe that has been weakened by repeated exposure to these events may experience fatigue failure. A pipe weakened by corrosion may also fail. Where very low pressures are possible during transient events, the engineer may choose to use a more expensive material to preclude the chance of collapse. For example, for large-diameter pipes under high pressures, steel is usually more economical than ductile iron or high-pressure concrete. However, the engineer may select high-pressure concrete or ductile iron because it is less susceptible to collapse and may eliminate the need for operational constraints.

Piping systems constructed above ground are more susceptible to collapse than buried pipelines. With buried pipelines, the surrounding bedding material and soil provide additional resistance to pipeline deformations and help the pipeline resist structural collapse. Above-ground pipelines must be anchored securely against steady-state and transient forces.

Using combination-air valves to avoid subatmospheric or vacuum conditions requires careful analysis of possible transient conditions to ensure that the air valve is adequately sized and designed. Several cases cited in the literature describe the collapse of piping systems due to the failure of an air inlet valve that was poorly sized, designed, or maintained. Combination-air valves can provide reliable surge control, but the potential for operational failures in air valves should not be ignored.

Other factors that influence extreme transient heads are pressure wave speed and liquid velocity. Selecting larger diameters to obtain lower velocities with the purpose of minimizing transient heads is acceptable for short pipeline systems delivering relatively low flows. However, for long pipeline systems, the diameter should be selected to optimize construction and operating costs. Long piping systems almost always require transient protection devices.

After considering these factors during the conceptual and preliminary designs, the project should move into the final design phase. Any changes to the system during final design should be analyzed with the transient model to verify that the previous results and specifications are still appropriate prior to commissioning.