138 



SEWER DESIGN 



water wasted, a law of daily variation is to be found for all 

 places, and that the maximum flow is from 50 to 100 per cent 

 greater than the average flow. The obvious method, then, 

 for determining the proper amount of house-sewage flow is to 

 determine the probable daily water-consumption per capita at 

 the future time for which the sewers are designed. About 

 75 per cent of this might then properly be assumed to be the 



TYPICAL HOURLY QUANTITY 

 OF SEWAGE 



GLOVERSVILLE, NEW YORK 



QUANTITY OF DOMESTIC SEWAGE, MILL 



WASTES AND DOMESTIC AND MILL SEWAGE 



COMBINED. DISCHARGE PER HOUR 



8 a 10 11 12 1 2 



P.M. 



FIG. 44. 



sewage flow. It will be safer, however, to assume that the 

 maximum water rate will be the maximum sewage flow, and 

 that any extraordinary excess in water rate will be partly com- 

 pensated for by the fact that really only about three-quarters 

 of such excess will reach the sewers. Therefore, add 100 per 

 cent to the average water-consumption for the maximum rate 

 of flow, and the result is the amount of flow for which the sewer 

 must be designed if it is to be limited to house-sewage. This 



