The operation and maintenance costs of non-sewered sanitation systems can be relatively large, involving, for example, regular removal and disposal of sludge from latrines and septic tanks and regular cleaning of toilets and latrines.
51. 没有污水道的环卫系统的运作和保养费用较高，其中要求经常从公厕和化粪池掏走并处理污物，经常清扫恭桶和厕所。