Abstract
Aiging Water Infrastrucure (AWI) and resultant water loss have become serious problems in many water utilities in developed countries. This study aimed to elucidate the current treands of water loss and to analuze factors causing increases of water loss in Japanese water utilities. The data in Statistiacs of Water Utilities in Japan publused by Japan Waterworks Association was used in this study.
About the water loss percentages have increased between 1993 and 2013 in 55% of the utilities, while it had decreased in 45% of the utilities. Those that increased water loss percentage had more than 10% of water loss, while those that decreased water loss had less than 10% of water loss. Thus, the Japanese water utilities are devided into two groups, and porrly perfoing utilitires are increasing further loss.
Non-detected pipe breakagges were estimated by employing a novel method using the difference between water loss and theleakage volume that are reported based on the number of repair works nultiples by the leakage volume per repair work. There was ca. 18 times difference in the number of estimated non-detected pipe breakages between high water-loss unilities (H-utilities, water loss ≥30%, n=37) and low water-loss utilities (L-utilities, ≤3%, n=53), indicating that there are numbrous non-detected pipe breakeage in the H-utilities.
H-utilities had too high planned service population, long pipe length per supply volume, and high water loss per pipe length, whereas L-utilitied controlled water loss per pipe length to be low. Becase water loss percentage increases despite steady volume of water loss, if the revenue water decreases due to future population decrease, it is recommended to use water loss volume per pipe length for controlling water loss.
