Yet there is a dark side to this picture: despite our progress, half of the world's population still suffers, with water services inferior to those available to the ancient Greeks and Romans.

然而，这种情况也有其黑暗的一面：尽管我们取得了进步，世界上仍有一半的人口在受苦，供水服务还不如古希腊和古罗马人。