Determination of economic impacts of interior water conservation measure on an individual household and a hypothetical water treatment plant

This study was to determine economic impacts on a household and a hypothetical water treatment plant resulting from implementation of interior water conservation measures. Installation of the water-efficient devices are considered as the measures to achieve interior water conservation. Three available water-efficient devices, toilet, shower, and faucet fixtures, are considered to formulate alternatives for this study. In determining impacts on a typical household, the base data sets are collected from the literature. Some of these data sets are also used to determine the impact on the hypothetical water treatment plant. Seven alternatives composed of the selected waterefficient devices were developed to determine impact on an individual household. By applying the principles of engineering economics, net annual savings due to replacement of conventional devices by the alternative devices are calculated. The net annual savings were calculated for two types of households: (1) household with one bathroom, and (2) household with two bathrooms. The values of net annual savings are used to determine the cost effectiveness of each of the alternatives. A hypothetical community and a hypothetical water treatment plant were used for determining impacts on a water treatment plant due to implementation of interior conservation measures. Considering the variability among the population in adopting water-efficient devices, a total of 21 alternatives were formulated. The alternatives are composed of different combinations of water-efficient devices. For each of the alternatives, impacts on the hypothetical water treatment plant are determined in two cases: (1) with conservation and (2) no conservation. In determining the long-term impacts ( period of deferred expansions, saving in the capital and operation and maintenance costs), population and water demand are forecasted for the study period. Water demand lines are plotted for both the cases (with and no conservation). An optimum expansion cycle for the water treatment plant was also estimated. Then for each of the alternatives, various periods for deferring expansion of the water treatment plant are calculated. As adoption of each alternative deferred the scheduled expansion of the hypothetical water treatment plant, savings in capital costs were generated. The present worth values of savings in capital cost are quantified. Present worth values of savings in the operation and maintenance costs were also calculated. The results of this study show that replacement of any of the conventional devices by the water-efficient one is cost effective for a household with one bathroom. Excluding the water-efficient toilet and faucet (TF) and toilet (T), adoption of the all possible combinations of the water-efficient devices are economically feasible for a household with two bathrooms. Adoption of a combination of the three water-efficient devices by the community produces from 50 or 200 percent higher savings in the total costs of the hypothetical water treatment plant than any combination of the two water-efficient devices or any single device. Due to interior water conservation, the hypothetical water treatment plant experiences much higher savings in capital costs than savings in operation and maintenance costs.