Extensive Experimental Investigation of the Pressure–Leakage Relationship in Water Pipes

It is widely recognized that leak areas in water distribution pipes are not fixed but vary with pressure. Leak area and flow behavior have been investigated in several experimental studies, but these were limited in scope and used different experimental setups and procedures. This study conducted 126 experimental tests on leaks in water distribution pipes with a range of leak types (round hole, longitudinal slit, and circumferential slit), sizes (small, medium, and large), pipe materials [steel, PVC, and polyethylene (PE)], pipe diameters (50, 100, and 200 mm) and wall thicknesses (Classes PN6, PN9, and PN12). The study confirmed that leak areas vary linearly with pressure, but that round holes and leaks in steel pipes can be assumed as rigid. Circumferential slits displayed small absolute, but mostly negative, head-area slopes. Longitudinal slits displayed large head-area slopes that increased exponentially with slit length, and decreased with pipe diameter and wall thickness. The impact of slit width on the leakage exponent was examined, and it was found that the larger manufactured widths used in experimental studies are likely to misrepresent the leakage exponents of narrower cracks found in the field.