The NWS&DB made an operational profit of 192 million rupees in 2009 with total revenue up by 36 percent, owing largely to the tariff hike, while operational and maintenance cost increased by 10.4 percent, it said.
The bank, in its annual report, drew attention to the high water losses suffered by the Water Board.
"The operations of the NWS&DB are hindered by a high level of unaccounted water losses due to various reasons."
Unaccounted water remains at around 36 percent in and around the capital, known as the Greater Colombo area, and 25 percent in regions.
"High incidence of leakages as a result of a decayed distribution network, illegal connections and shortcomings in meter readings are the major reasons for unaccounted water," the Central Bank said.
The cost of purification of water has increase