The need for water is common to all living things. Man's health and well-being depend upon an adequate water supply to fulfil his bodily needs, to make hygiene possible and to produce the food he eats. Where water is inadequate, life is a struggle for existence.
Fresh water occurs naturally on the earth's surface in springs, streams, rivers and lakes. However, these sources of water are not uniformly distributed. Moreover, they may be intermittent and it would severely limit the locations where man could live if he had to depend solely on surface water. This constraint spurred man to learn how to sink wells to exploit underground water thousands of years ago. The ability to create a water supply which is dependable, clean and in a desired location is a skill which should be ranked second to none in the development of mankind. The social and strategic importance of wells can be learned from many historic accounts.
In addition to supplying man's own needs and those of the animals he raises, water from wells may be used to irrigate the crops which produce his food. Sometimes irrigation is the sole source of water for plants. In other cases irrigation water may be used only to start plants in seedbeds, so that they may make maximum use of natural rainfall when it becomes available. In still other cases, irrigation may be used only to supplement rainfall when it becomes insufficient. In the last two cases, relatively small quantities of water can lead to big increases in yields. Irrigation may also make it possible to have fresh fruits and vegetables in the diet when they would otherwise be unavailable.
While very sophisticated and expensive well drilling equipment has been developed, especially in response to demands of the petroleum industry, an amazing variety of simple, low-cost techniques exist. These techniques tend to be low capital labour intensive, and have been successfully used under many conditions on self-help well construction projects around the world. Since in many areas people are under-employed at some time during the year, their spare time can be used toward the improvement of their own well-being and toward an increased economic base through irrigation.