AWWA ACE60092

The recent experience of two very similar medium-sized water systems in Hawai'i provides acase study in the role of an inverted block rate structure in helping to promote conservation. TheCounty of Hawai'i Department of Water Supply (Hawai'i DWS) serves potable water toapproximately 36,600 residential, commercial, and agricultural customers on the island ofHawai'i. The County of Kaua'i Department of Water (Kaua'i DOW) serves approximately18,400 residential, commercial, and agricultural customers on the island of Kaua'i.In July 2001 both water systems implemented large rate increases (approximately 29 percent atHawai'i DWS and approximately 32 percent at Kaua'i DOW) to fund significant capitalimprovements needed on each island. A major difference between the two systems, however,was their rate structures. Hawai'i DWS has maintained an inverted block rate structure for all ofits customers for more than two decades. Kaua'i DOW previously had a uniform (flat) ratestructure and in 2001 initiated an inverted block rate structure for its customers. Although thetwo utilities are similar in many aspects (including customer profiles and overall weatherconditions), a preliminary review of customer reactions to these two large rate increasessuggested a more significant reduction in water usage at Kaua'i DOW than at Hawai'i DWSsince 2001.This paper compares the water usage experiences at Hawai'i DWS and at Kaua'i DOW since2001. In particular, the paper examines and quantifies the effect of implementing aninverted block rate structure at Kaua'i DOW in 2001. A review of water consumption patterns atthe two water systems is presented to compare whether Kaua'i DOW's switch from a uniform ratestructure to an inverted block rate structure corresponded with significant changes in waterdemand patterns, and if these changes are different from those at Hawai'i DWS. Specifically,this paper considers the hypothesis that an initial conversion to an inverted block rate structurecan reduce water consumption, but then, once an inverted block rate structure is established,further changes in rate structure have less impact on water consumption. These and other raterelated water conservation topics are addressed in the paper. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/17/2004

Number of Pages:

7

File Size:

1 file