Unaccounted-for Water Project Puerto Rico

Client: Puerto Rico Aqueduct and Sewer Authority (PRASA)

Contract Period: 2007-2010 (Project Duration: 3 years)

In 2007 over 60% of total water production by the P.R. Aqueduct & Sewer Authority (PRASA) was not accounted-for by customer meters, and no quantifiable information indicated on where or why these losses occurred. GLM Engineering undertook for PRASA a $3.6M pilot project to quantify water losses in representative areas and land use types of Puerto Rico and to develop and implement remedial actions. The project was performed in stages, from problem diagnostic through initial implemen­tation of remedial measures. This was the first project to quantify water losses in Puerto Rico and initiated the Authority’s efforts to implement a proactive water loss management program.

Diagnostic work involved inventory, individual testing and monitoring of 25,000 customer meters within water distribution sectors in Cataño, Corozal and Yauco that had been tested for closure and metered to account for both monthly water balances and continual metering to compare day vs. night water use to quantify leakage separate from theft. It also included leak detection, leak repair, monitoring of leakage vs. pressure, and review of customer billing records for conformance with field conditions.

Large metering errors occurred, particularly with large meters. Substantial sources of error included both meter accuracy and reader errors. GLM developed and deployed a field data loggers to initiate the complete island-wide meter census to rectify the billing database. Study results showed that better metering would increase revenue, but the leakage rate was so high that metering alone would not adequately control water loss. In many sectors leakage was so severe that multiple iterations of leak detection and repair were necessary because large-leak noise obscured small leaks.