Before deciding on a source, however, consider what the daily needs will be. From long observation, it has been found that the average country place requires fifty gallons of water a day for each member of the family, servants included. Then allow for two extra people so that the occasional guest, whose knowledge of water systems begins and ends with the turning of a faucet, will not unduly deplete the supply. For example, a family of seven should have a daily water supply of from 400 to 500 gallons depending on how much entertaining is done and how extensive are the outdoor uses. This allowance will be ample for toilets, baths, kitchen and laundry, as well as for moderate watering of the garden and lawn. Of course, if cars are to be washed regularly, fifty gallons should be added to the daily demand. If there is a swimming pool, its capacity should be figured by cubical content multiplied by seven and one-half (the number of gallons to the cubic foot) and allowance made for from fifteen to twenty-five per cent fresh water daily.
The daily production of a spring or drilled well can be easily gauged. A flow of one gallon a minute produces 1,440 gallons in twenty-four hours. In other words, a flow of ten gallons a minute means 14,400 gallons a day which, at fifteen gallons a bath or shower, is enough water to wash a regiment from the colonel to the newest recruit.
Estimating the daily production of a shallow, dug well is more difficult. The number of gallons standing in it can be obtained by using the mathematical formula for the contents of a cylinder, but only observation will tell how quickly the well replenishes itself when pumped dry. By long experience, however, country plumbers have found that if such a well contains five feet of water in extremely dry weather, it can be relied upon for the needed fifty gallons a day each for a family of seven with enough over for safety.
In fact, with all water sources except an artesian or driven well, the question always is, will it last during an abnormally rainless season? Never-failing springs and wells that never go dry are institutions in any countryside. So consult some of the oldest inhabitants. They know and if they give your well or spring a good character, the chances are that even the most exacting of families will find such a water supply adequate. Whether it is pure or not is another matter but one that can easily be determined by sending a sample to your state health department or a bacteriological laboratory. That this should be done before such water is used for drinking purposes goes without saying.
The driven or artesian well has two points that makes it worth the cost. There is no question of purity or of quantity. It taps subterranean water which is unaffected by local causes of contamination or by drought.