AMOUNT OF SEWAGE PER CAPITA 107 



consumption for 1896. Fig. 25 shows the two curves for Des 

 Moines, Iowa, for 1895.* Both diagrams show the sewage- 

 flow to be about 35 per cent less than the water-consumption. 



The variation in the water-supply of a city is almost incred- 

 ible, cities of the same size and character often having a 

 difference in daily consumption of as much as 150 gallons 

 per head. To what cause this is due it is hard to say, as there 

 seems to be no law as to the relation between the consump- 

 tion and the size of the city. Nor does any one cause seem 

 responsible. Probably the largest factor is leakage, caused 

 by poor construction of the main line, and in the house-fixtures, 

 and by carelessness on the part of the house-holder and by 

 neglect on the part of the water-works superintendent in 

 making proper repairs. Any discussion (notably such as have 

 taken place in the New England Water-works and in the 

 American Water-works Associations) on the question of leakage 

 brings out its importance very plainly, and the reports on the 

 various devices for detecting water-waste make their efficiency 

 unmistakable. For example, in his annual report for i8g2, 

 Mr. Trau twine mentions that in Philadelphia, out of 782 appli- 

 ances in 142 houses inspected for waste, 22 were leaking slightly 

 and 32 running continually. The daily consumption per capita 

 for these houses was found to be 222 gallons, of which 192 

 were wasted, 30 only being used. It is generally in the smaller 

 cities that municipal oversight is most lax, the increased con- 

 sumption in the larger cities making a total volume of waste 

 so large as to demand investigation; yet this has so many 

 exceptions as to be of little value. 



The following tables are given to show what amounts of 

 water are actually used per head per day in typical cities of 

 the United States. Most of the figures given are derived 

 from the records of pumping-plants, because actual measure- 

 ments of the amount of water used in gravity supplies are very 

 few. From the meager data available there seems to be no 

 reason to believe that the fact and cost of pumping offers 



* The data supplied through the kindness of Professor Marston, Ames, Iowa. 



