Water demand management optimization methodology

Abstract

In contrast to traditional supply augmentation options, demand management options include specifying and/or replacing many small end uses that individually have a minimal effect on overall water use but that collectively can constitute significant aggregate reductions in demand. This article outlines a systematic procedure to quantify savings potential of single-family residential indoor end-use devices of a given utility and then select the optimal blend of retrofits to achieve a specified goal. Three steps are used to quantify savings potential of all end-use devices. First, a utility's current end-use fixture inventory and associated water use is estimated from parcel-level data for each singlefamily residence. Second, customers are clustered into relatively homogeneous water use categories based on the age of the dwelling unit and the number of bathrooms. Third, water savings are calculated directly as the difference between current and proposed use after implementation of a management option for each group. This information is used to develop performance functions that estimate total water savings as a function of the number of fixture retrofits for each group. W ater demand management can be a viable alternative to augmenting a supply system to meet future water needs. Demand management should be compared with traditional supply augmentation methods to decide whether it is a viable option. Methods of analysis are well-established for choosing among supply augmentation options such as well field development, reservoir and pipeline construction, and desalination. Demand management is an emerging alternative in which several case studies have illustrated significant demand reduction from various strategies, including technological improvements, behavioral marketing campaigns, and adjustments of water pricing. The major difference between traditional supply augmentation and demand management is that traditional supply options are capital-intensive with long service lives; as a result, capacity expansion is done in discrete, relatively large, increments. Demand management options include many small changes that reduce water use for individual customers by a few gallons per day but that collectively can bring about significant aggregate reductions in demand if applied to a significant portion of the utility's customers.Advances in database availability, including an associated geographic information system (GIS), make it possible to do a bottom-up evaluation of water demand patterns across the utility and systematically determine the potential savings for all single-family indoor retrofit options within a given utility. An optimal mix of demand management strategies can then be selected by comparing each demand management control with a few large supply augmentation options. Existing

Predicting and managing residential potable irrigation using parcel‐level databases

“…This information is used to develop performance functions that estimate total water savings as a function of number of implementations for each group. This procedure allows demand management options to be compared directly with other supply augmentation options when determining the optimal blend (Friedman et al, 2011). The performance functions can be approximated as exponential equations, which can easily be solved for finding an optimal solution given unit costs and value of water saved.…”

“…Otherwise, outdoor water use was determined via hydrograph separation, as shown in . Indoor water use estimates were generated using an end‐use modeling framework described elsewhere (Friedman, 2011).…”

“…However, estimated average indoor water use for single metered residences using the minimum month method is the same as for the dual‐metered customers, showing the consistent nature of indoor water use. Indoor water use estimates can be improved using an end‐use modeling framework (Friedman et al, 2011). Water year 2008 (October 2007 to September 2008) was selected to estimate indoor water use in order to be consistent with the time period of the available billing data.…”

“…This database structure can be used for end‐use evaluations for any urban water sector. For example, Morales et al (2011) show how such data can be used to analyze end uses for the commercial, industrial, and institutional sectors. For a complete list of fields applicable to residential parcel level urban water analysis, refer to Friedman et al (2011).…”

Decadal review of residential water demand analysis from a practical perspective

“…To gather information to support practical sustainable policies nationwide, residential water meters are being introduced in many areas to help pinpoint areas of high water demand and highlight areas where recycled or reused water may offer a viable alternative (Friedman et al 2011). Accurate water demand analysis and associated modeling efforts are also vital for designing/operating water distribution network and treatment systems and identifying appropriate water resources (Filion et al 2007).…”