EXPERIMENTAL INVESTIGATION OF LEAKAGE–PRESSURE RELATIONSHIPS IN WATER DISTRIBUTION SYSTEMS EFFECTS OF SURROUNDING MEDIA AND ORIFICE SIZE

Abstract

Leakage in water distribution systems (WDS) continues to impose substantial economic and environmental costs worldwide. Although leakage is often modeled using the orifice equation with a square-root dependence on pressure, these representations typically assume free discharge conditions and rarely account explicitly for the surrounding medium. This paper presents a controlled laboratory study that quantifies how surrounding media—air, water, and saturated sand—modulate leakage rate, discharge coefficient, and the leakage–pressure relationship for small circular openings. Four steel pipe test sections (12 mm internal diameter) with orifices of 1, 3, 6, and 9 mm were evaluated over pressures up to 70 kPa. The apparatus ensured single- orifice flow, accurate pressure measurements via a calibrated gauge, and repeatable data collection. Results show that discharging into water produces leakage trends comparable to free discharge into air, with leakage approximately proportional to pressure to the 0.5 power and discharge coefficients 𝐶𝑑 ≈0.6–0.7. In contrast, discharging into saturated sand dramatically attenuates leakage—frequently by an Majed O. Alsaydalani https://iaeme.com/Home/journal/IJCIET 36 editor@iaeme.com order of magnitude relative to air—and reduces the effective discharge coefficient by up to ~93% (e.g., 𝐶𝑑 falling from ~0.65 to ~0.045 for a 3 mm orifice). Moreover, the soil case exhibits a near-linear pressure–leakage relation up to a threshold (~30–40 kPa), beyond which disproportionate increases in flow are observed and soil piping initiates (noted near ~32 kPa for a 9 mm orifice). These findings challenge the notion that surrounding soil has negligible impact on leakage and underscore the need to incorporate media effects into leakage modeling, pressure management, and risk assessment.