WHAT USES DO WE MAKE OF WATER? 



93 



that such water might be very unsafe. If water is taken 

 from a well, the well should be protected by a cap of 

 cement, as shown in the diagram, and it should be so 

 located that drainage cannot enter it. Well water should 

 be tested frequently 

 for germs by town 

 or state Boards of 

 Health. A well in 

 ordinary sandy soil 

 situated above and at 

 least 100 feet from 

 any cesspool is safe. 



You may go camp- 

 ing and be in doubt 

 about the safety of 

 your water supply. 

 Boiling it for 20 min- 

 utes will kill prac- 



Compare the conditions of these two wells. 



Under what conditions might the water in B be 



safe ? When unsafe ? 



tically all harmful 



germs and will make 



it safe for drinking. 



Unfortunately, boiling drives off the free oxygen and 



gives it a flat and unpleasant taste. The oxygen can 



be put back into the water by violently shaking it for a 



short time in a bottle partly full of air. 



Water Used in Cooking. Water is also used to cook 

 foods in. We make our bread by mixing flour with water 

 to form dough. We make our tea and coffee because of 

 the solvent action of water which extracts the flavor 

 from the tea leaves or the ground coffee so that the liquid 

 has the flavor instead of the original tea and coffee. We 

 can also transfer heat by means of water or steam, as you 

 see when you cook a cereal in a double boiler. 



Other Uses of Water. We have seen that both plants 

 and animals are made up very largely of water. This 



