The combined system, in which one sewer only is provided for everything,is not to be recommended.Overflows are necessary, as with the previous system,but the risk of pollution is even more acute.

• 合并式只用一条管道排放所有的废水,建议不要采用。这种设计同半分离式一样需要设置排溢口,而污染的危险比前者更大。