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Water Consumption and Return-to-Sewer (RTS) Study

Water Consumption and Return-to-Sewer (RTS) Study

return to sewer
Background

Although the consumption of water in Abu Dhabi is high, less than 20% of the total water delivered to the transmission system is “Returned to Sewer” (RTS). This means that over 80% water ends up on the ground. Our goal is to encourage a more efficient use of water and increase the amount that is recaptured after use.

This project was part of an initiative to calculate and analyse RTS rates to provide information and aid in the development of a long-term water resources strategy for the Emirate, particularly those components related to typical water consumption patterns from different property types in the Emirate, water planning and forecasting tools, and potential volumetric tariff approaches.

Examination of the findings of an initial  water consumption and return-to-sewer (RTS) project involving many unknowns and multiple organisations to critically assess the methodologies used by the Regulation and Supervision Bureau for the Water, Wastewater, and Electricity Sector for the Emirate of Abu Dhabi.

The Project

In 2010, a pilot study was commissioned to investigate the potential of calculating RTS rates from seven selected catchments within Abu Dhabi Island and adjacent areas. The key aspect of an RTS calculation is the balance between the volume of potable water entering a specific property or group of properties and the volume of wastewater leaving the properties within a specified period. Understanding the key factors that influence determination the volumes of wastewater and potable water was a critical part of this project. In gaining an understanding of these factors, an assessment was made of the evidence-based data obtained from interviews and a subsequent data collection process, and an opinion about the level of confidence in this data was provided.

The project focused on a review and commentary of an earlier pilot study relating to the selection of seven discrete catchments, the approach to data collection, and interpretation of this data, and provided a specialist view on the data collection methodologies used. Other issues that required consideration relate to infiltration, metering accuracy and matching the boundaries of the selected catchments.

This project was packaged into three related tasks:

  • Review the pilot study conducted in 2010
  • Define the key factors influencing RTS calculations
  • Recommend further work required
The Outcome

The project team developed and implemented an innovative technique to assess the relative gravity (or seriousness) of the various factors that influence the determination of RTS values. The overall analysis was based upon an assessment that approximates the quality of data through a comparison of various indicators and benchmarks within the range of the specific indicator or benchmark. This generic approach provided the flexibility necessary to assess various types of data sets. The quality assessment process therefore ensured that the data were marked as reliable, average (e.g. mediocre) or unreliable.

The assessment process led to the formulation of recommended strategies to address anomalies in establishing RTS values in specific catchments as well as for future RTS studies.