Bulgarian NRW KPIs


Update of Bulgarian Ordinance

An update of the Bulgarian Ordinance for Regulation of the Water Supply and Sewerage Services Quality redefines the indicator used to express calculated total water losses in water supply systems. The ratio between non-revenue water and System Input volume, used in the previous (2006) Ordinance, is to be replaced by m³ per km of mains per day.

The new Ordinance, some 70 pages long, to be published later this year, contains an overview of the most important topics in control of Non-Revenue Water. The annual Water Balance follows the basic principles of the IWA recommended Standard Water Balance (2000). The drafting Group drew on experiences of national, European and international references, including  the EU Reference document on good practices on leakage management (2015), which included Case Studies of two Bulgarian systems. The wider international trend to move from use of percentages or ratios between Non-Revenue Water and System Input Volume, to ‘fit for purpose’ performance indicators, was recognized.

Water losses in Bulgarian Water Utilities have been very high for many years, whichever performance indicator is used. The new Bulgarian Indicator QI4 of m³/km/day is ‘fit for purpose’  for tracking reductions in individual systems in coming years, when management of both excessive NRW and consumption is being implemented at the same time;  but it does have limitations if used for comparing performance of different Utilities or setting the same target for all Utilities, as it does not allow for differences in connection density and operating pressure.

The new Bulgarian Indicator QI4 of m³/km/day is clearly recognized as suitable for tracking reductions in coming years, when management of both excessive NRW and consumption is being implemented at the same time. Q14 water losses in a water supply system (m³/km/day) are defined as a ratio between the non-revenue water at the system input (excluding the water supplied to other water operators) and the length of the water supply network. The indicator is expressed using the formula:

QI4 = A15 / C8 / 365

where: A15    is the Non-revenue water, which is the difference between the system input volume (Q9, according to Ordinance No 1 dated 5.05.2006 for Approval of a Methodology for Defining the Admissible Water Losses in the Water Supply Systems to the Water Supply and Sewerage Services Regulatory Act, dated 20.01.2005, excluding the volumes supplied to other water operators and the billed authorized consumption ( m³);

and: C8 is the total length of the water mains and the distribution network, in km. Note that in Bulgaria, as in many other European countries, the length of the service connections (main to meter) is not included in the definition of Network Length.

Service level indicators in the new Ordinance  also include  QI5 – Failures along water supply network  (numbers/100 km/year).

This Guest Blog has been kindly provided by Dr Atanas Paskalev (Aquapartner, Bulgaria) and Dr Joerg Koelbl (Blue Networks, Austria)

Comments are closed.