bout double the amount of water used. It is only a reasonable
safeguard, therefore, if it has been decided that the family needs are
such as to require twenty-five gallons per head per day, to provide for
double that amount in order to meet the demands of excessive daily
consumption or of the hot and cold weather extremes.

_Fire streams._

If a water-supply is to be installed for any house, the possibility of
providing mains of sufficient size for adequate fire protection should
always be considered, although it may not be found to be a necessary
expenditure. In case of a fire a large amount of water is needed for a
few hours, entirely negligible if it is computed as an average for the
year, but a controlling factor in determining the size of mains or the
amount of storage.

A good-sized fire stream delivers about 150 gallons per minute, and for
a house in flames, four streams are none too many. The rate of delivery,
therefore, for a fire should be at least 600 gallons per minute or a
rate of nearly a million gallons per day, and if it is assumed that the
fire might burn an hour before being extinguished, 36,000 gallons of
water would be used. If a spring or tank is the source of supply, the
storage should be 36,000 gallons, and the pipe line from the tank to the
hydrants must be large enough to freely deliver water at the rate of 600
gallons per minute. If the distance is not over 500 feet, a four-inch
pipe is sufficiently large; but if the distance involved (from the
reservoir or tank to the farthest hydrant) is more than about 500 feet,
four-inch pipe is not large enough. This is because the friction in a
large line of pipe is so great that the water cannot get through in the
desired quantity. A four-inch pipe, discharging 600 gallons a minute,
would need a fall of one foot in every four feet, while a six-inch pipe
would need a fall of only one in thirty. Of course, if the reservoir
from which the water comes is at such an elevation that the greater fall
is obtainable, the smaller pipe may be used. It is more than likely,
though, that the reservoir is about 3000 feet or more away, and the
entire fall available only about thirty feet or one foot in one hundred.
Then an eight-inch pipe would have to be used.

Whether fire-protection piping, therefore, is a wise investment or not,
depends largely on the cost of installation. A four-inch cast-iron pipe
laid will cost about forty cents per running foot, while an inch