The African Development Bank is providing Sierra Leone with $61 million to upgrade its water supply in four provincial cities a year after a cholera outbreak killed hundreds, the west African state's water company said on Tuesday.

"Some of the water sites have been dilapidated for some 40 years and have reduced residents ... to depend on well water and filthy streams for drinking and domestic work," said Alimany Kamara, regional station manager of the Sierra Leone Water Company.

Sierra Leone remains one of the world's poorest countries after a brutal 11-year civil war which ended in 2002 and it is struggling to rebuild water and sanitation systems.

Last year the country suffered its worst ever cholera outbreak with 20,000 people infected and more than 300 killed.

The ADB funding will take the form of a loan and the work is expected to begin in October, although Kamara did not specify a completion date.

Only 15 to 20 percent of residents in provincial cities have access to clean water, according to government data.