While for the average ordinary consumption of water, expressed in gallons per head and day, _q_, Mr. Coffin’s formula, as given in his paper previously cited, may be taken _q_ = 40_x_⁰˙¹⁴. (5) By combining equation (5) with equation (4), remembering that the maximum rate of consumption is usually about 1.5 times the average, the total draft in gallons per minute upon the discharging system at the time of a conflagration will become as follows: ___ 3 40 × 1000 _Q_ = 250(2.8 √_x_) + ---- ---------- _x_¹˙¹⁴ 2 1440 ( ___ _x_¹˙¹⁴) = 250(2.8√_x_ + --------) (6) ( 6 ) This maximum rate of consumption during a conflagration does not affect the total supply of a large city like New York, Boston, or Chicago, but it may become of relatively great importance in a small city or town. In a large city this draft may and frequently does tax the capacity of a small district of the discharging system. In designing such systems, therefore, even for large cities, it is necessary to insure all districts against a small local supply when a large one may pressingly be needed. CHAPTER XV. =155. Waste of Water, Particularly in the City of New York.=—The quantity of water involved in designing a water-supply for cities and towns is much larger than that which is actually needed. The experience of civil engineers in many cities, both in this country and in Europe, shows conclusively that the portion of water actually wasted or running away without serving any purpose will usually run from 30 to 50 per cent of the total amount brought to the distributing system. In the city of New York there is strong reason to believe that the wastage is not less than two thirds of the total quantity supplied. It is frequently assumed that both the quantities supplied and the quantities uselessly wasted in New York are larger than in other places. As a matter of fact those quantities are actually smaller than in some other large cities. While the supply per inhabitant in New York City is much larger than should be required, the use of water by its citizens is not extravagant when gauged by the criterion of use in other large cities. This question was most carefully and exhaustively investigated in 1899 and the early part of 1900 by Mr. John R. Freeman of Boston, acting for the comptroller of the city of New York. The usual wastes of a water-supply system may be distributed under six principal heads. First, leaky house-plumbing; second, and “possibly first in order of magnitude,” leaky service-pipes connecting the house pipe system with street-mains; third, leaving water-cocks open unnecessarily; fourth, leaky joints in street-mains or pipes; fifth, possibly pervious beds and banks of distributing-reservoirs; sixth, stealing or “unlawful diversion” of water through surreptitious connections.