There is a wide range of difference in the amounts estimated, for under some conditions, a minimum of seventeen gallons, or even twelve gallons, would be sufficient, while under other circumstances and in other localities as much as 300 gallons per day per individual would not be an excessive or wasteful amount. The average amount estimated per individual per day for domestic purposes is placed at seventeen gallons for all purposes. In 1918 the statistics showed that Buffalo used an average of 260 gallons per capita per day, but many cities used much less. In Berlin in 1913 the water consumption amounted to an average of twenty-four gallons per capita per day.
The hygienic importance of these figures is insignificant since they are only approximate. There are a number of factors that are not taken into consideration. The figures are estimated on the number of gallons of water pumped and no account whatsoever is taken of the water waste through precipitation and loss through leaky pipes. Some engineers maintain that fully half the water pumped is lost in these various ways. Another thing that must be considered when comparing the amount of water used by different cities is the industries. Some industries require much more water than others, therefore, if a just comparison is to be made between cities only the water that is actually passed through the private meters must be considered.
Water Waste
Consideration of the subject of water would not be complete without some reference to the amount of water that is wasted. It seems a small matter to waste water. We sometimes say there is plenty in the river. But the proposition of preparing the water for use and getting it to the individual for consumption may involve many phases of hygiene from several different angles and one of these angles may be industrial hygiene. To get water into the home and factory requires a great many processes such as laying and maintaining water mains, purifying the water and pumping. This involves several industries and trades, so the problem of a water supply is far reaching and is of vital importance to the community.
There should never be a sacrifice on the part of hygiene and cleanliness for the purpose of saving water. A sufficient amount of water should at all times be insisted upon, but certainly there should be a strenuous effort to eliminate undue waste.
The main causes of water waste will be found to be leakage in mains and service pipes and waste from defective fixtures in the house. All of this leakage and waste should be properly attended to because of the direct relation which it bears to hygiene and particularly to industrial hygiene.
The introduction of meters has been an important factor in reducing water waste. It is not the thought to limit the amount of water used or to deprive one of a sufficient amount, but there is nothing to be gained by an unnecessary waste. The introduction of meters in Milwaukee reduced the amount of water used per tap from 1,781 gallons per day to 644 gallons per day without putting any restrictions upon the consumers. It is an enormous task to provide a sufficient amount of pure clean water for a large city and certainly an effort should be made to avoid waste.
SOURCES OF WATER SUPPLY
Rain Water
The sources of our water supply may be classified as: Rain and snow water, surface water and ground or subsoil water.