The water from most wells is clear and cool, but nevertheless may contain many disease germs. "How does this happen?" you ask. Because the well is too close to an out-house or some other source of filth. When a man in the country or in a small town builds a house, he immediately thinks of digging a well just as close to the house as he can, so that he need not carry the water far. Next he thinks of locating the closet, and this, too, he wants near the house. The well and the closet are often near each other, and often the closet is on higher ground than the well. The vault under the closet is seldom water-tight. In fact, the intention of the owner is that a great part of the vault contents shall soak away. In many localities the ground is an open gravel, and the vault contents run through this gravel into the well, carrying disease germs with them. In one little town, with wells as a source of drinking water, the health officers found that the closet of every house was draining directly into its well. In some countries vaults can be used; but in any region where there is a gravel subsoil, the contents of the closet will find their way into the well, unless the closet is lower than the bottom of the well. In such places the vault must be made water-tight, in order to keep the vault contents out of the well.[2] [Sidenote: Why springs are not always pure] Springs are usually sources of pure water, but do not think that every particle of water that oozes from the ground is a spring. Near a certain town is a so-called "very fine spring." This "spring" appeared after a man had made a cesspool on the hill above, and is simply the drainage from the cesspool. Springs that come from deep sources, however, nearly always contain pure water. [Sidenote: The safest sources of water] The safest source of water for domestic use is a stream that is known to be free from contamination, or a well so deep in the ground that it is hard for any polluting matter to reach it. But remember that sewage may follow a well pipe along the outside and thus reach even a deep well, if the well is not properly protected at the top. Keep disease germs out of your drinking water. You cannot drown them out and you cannot strain them out, so do not let them get in, for you cannot drink water containing disease germs without running the risk of becoming sick. =Questions.= 1. Mention more than one way in which germs get into streams. 2. How long may disease germs live in running water? 3. Mention some instances showing that running water does not purify itself. 4. How do disease germs get into milk? 5. Describe the proper location of a well in regard to refuse. 6. How may springs become polluted? 7. What are the best sources of water for domestic use?