Abstract:
Performance assessment of water supply and wastewater services is today a major issue. Over the
past six years, the National Civil Engineering Laboratory (Portugal) has been developing performance
assessment systems for drinking water treatment plants (WTPs) and wastewater treatment plants
(WWTPs). In 2009, a national field-test was launched in Portugal, ‘PASt21’, involving 27 plants (10
WTPs and 17 WWTPs). This paper presents an overview of the second generation of the performance
indicator (PI) systems for the overall performance assessment of WTPs and WWTPs, the extent to
which the systems were applied in the 5-year study period (2006–2010), and the aggregated results
(average, median, percentiles 25 and 75, maximum and minimum) of representative PIs in each
assessment group. It was concluded that all indicators are relevant, and the results show the ability
of the proposed PI systems to assess the overall performance of a given treatment plant. The
aggregated results are very important for the continuous improvement of the plant performance
through benchmarking and periodic reassessment of targets.
