SANITAKY DRAINAGE OP WASHINGTON. 15 



supplied, where they are so abandoned, by smaller pipes for house- 

 drainage. 



Assuming this belief to be well founded, the problem to be con- 

 sidered is, in what way best to make use of such of the sewers of 

 Washington as are suitable for the purpose ; and in what way to 

 introduce new works so that the system by which the houses are to 

 be drained shall conform to the best requirements ; and in what 

 way best to dispose of the outflow, to the end that no house in the 

 city may be connected with a sewer which at any time or under 

 any circumstances may retain organic matter in a state of decom- 

 position ; and that no house may discharge into a sewer whose use- 

 fulness is ever, even temporarily, interfered with by storm-water or 

 by back-flow. In short, to give to every house a clean and well- 

 ventilated channel to carry its waste matter to a point whence no 

 ill effect may return. 



To determine to what extent and precisely in what manner the 

 present sewers can be made useful as a part of this system, would 

 require more detailed knowledge concerning them than I now 

 possess. One important question would be the extent to which it 

 would be cheaper to construct at the heads of the sewers flush- 

 tanks large enough to keep them clean, than to substitute for them 

 smaller pipes which would be more cheaply flushed. Another 

 would be to determine the cost of making the present sewers 

 absolutely tight. Even pipe-sewers, as ordinarily laid, are very 

 apt to leak at the joints to such a degree as to rob the sewage of its 

 water, and to contaminate the soil. 



So far as the present sewers cannot be made to conform to the 

 requirements which I have indicated, they should undoubtedly be 

 reserved for street use only, and new small ones with absolutely 

 tight joints should be furnished to take their place as an outlet for 

 house drainage. 



Let us for the moment assume that all of the existing sewers of 

 the higher parts of the city can be made suitable for the work, 

 and that it will be cheaper to flush them, large though they are, than 



