As Nelson Mandela Bay municipality’s dams dwindle and growing emphasis is put on sourcing water from the Nooitgedacht treatment works — serious problems have emerged on the Gariep-Fish-Sundays line that supplies the plant.

Because of leaks and equipment failures, Darlington Dam, the second-biggest dam in the Eastern Cape and an important cog in the Gariep line, can supply only about 20% of its capacity...