CATHERINE SCHENCK and ANAIT MIRIDZHANIAN IN a dilapidated block in the business district of Africa's wealthiest city, Johannesburg, Thulani Cele and 300 others squatting in the building fill buckets with water from the only working tap so they can drink and wash. "We are living in a terrible situation. We need toilets ... We need water," says Cele, a 40-year-old former retail worker, who adds that residents have no sanitation and must use buckets as toilets. The Johannesburg Department of Housing has said one of its priorities is providing water and sanitation to informal settlements and all residents deserve quality…