Deterioration in public water supply systems
Inadequate maintenance of urban water systems
Failure to maintain sewage systems
Deficient municipal water lines
Leakage from city water supply systems
Water leaks in cities
Because of low revenues and spiralling costs of purifying water for urban areas -- increasingly from lakes and reservoirs polluted by urban discharges and runoff -- local authorities may often neglect the maintenance of their water distribution systems, and delay repair or extension of systems into peri-urban areas outside the traditional distribution network. This can compound the possibility for water pollution and also contribute to cross-contamination of potable water supplies by wastewater or sewage.
In 1996 it was estimated that nearly half the water supplied to cities is lost because of leakage and wastage, often the result of neglect and profligacy. 'Unaccounted-for-water' in Nairobi, Kenya is estimated to be enough to supply all of Mombasa, Kenya's second largest city.