The Dandora Waste Stabilisation Pond System in Nairobi, Kenya is the largest in Africa and effectively treats sewage. Despite handling only half its capacity, the ponds maintain good effluent quality meeting irrigation guidelines. A study on anaerobic ponds showed high BOD5 removal rates, exceeding predictions, even at low loadings without odour issues. This suggests that anaerobic ponds can operate efficiently below design levels, saving land and enhancing system performance. Monitoring programs are crucial for large pond systems to ensure optimal functioning.