74 



WATER SUPPLY 



What are the modern methods employed for sew- 

 age disposal? In rural homes supplied with running 

 water, the wastes are sometimes run into cesspools. 

 A cesspool is merely a hole dug in the earth and 

 loosely walled with stone or brick. The sewage which 

 empties into the cesspool is slowly absorbed by the 

 ground that surrounds it. This method of sewage 

 disposal is not a desirable one, especially if the cess- 

 pool is placed near a well or a spring. Why? 



A septic tank (Figure 116) is generally considered 

 the most modern and efficient method to use for dis- 

 posing of sewage. These tanks may be' built of brick, 

 concrete, or metal and may be divided into two or 



FARM DRAINAGE TILE 



FIG. 116. SEPTIC TANK 



more compartments. The compartments are so ar- 

 ranged that as the sewage passes slowly through them 

 the waste matter is acted upon by certain bacteria. 

 Solid substances are changed to liquids and gases, 

 and germs are killed by the action of these bacteria. 

 The liquid that finally flows from the septic tank into 

 the soil is usually almost clear, free from offensive 

 odors, and harmless. Any solid substances remaining 

 are destroyed by the action of bacteria in the soil. 



Perhaps the easiest method for disposing of sewage 

 is to pipe it into the nearest body of water. Towns and 

 cities along the seacoast generally pipe their sewage 

 a considerable distance beyond the ocean shore. Since 

 the quantity of wastes is small in relation to the large 

 volume of ocean water, sufficient dilution and break- 

 ing up of waste materials occur to make them harm- 

 less. Inland cities on or near rivers and lakes find the 

 disposal of sewage a more difficult problem. Untreat- 

 ed sewage, if dumped into streams, will not be purified 

 because the body of water is too small. Thus the 

 water becomes dangerously impure and endangers the 

 lives of people living in towns and cities farther down 

 the river. 



Some large cities pipe their sewage into very large 

 septic tanks which partly purify the waste. Then a 

 disinfectant (a substance which kills germs) is added, 

 and the liquid is drained into a body of water. In 



other inland cities the sewage is aerated before it is 

 emptied into a river. First the solid matter is removed 

 by screening. Then liquid wastes are pumped into 

 fountains that spray it into the air. While in the air 

 many of the germs are killed by the action of sun- 

 light and oxygen. The liquids fall on beds of coke 

 where bacteria continue the process of purification as 

 the liquids filter through. Then the liquid may be 

 finally filtered through a bed of sand or gravel which 

 completes the purifying process. 



REFERENCES FOR FURTHER STUDY 

 Texts 



Caldwell and Curtis, Science for Today, Chap. 5 

 Clement, Collister, and Thurston, Our Surroundings, Chap. 5 

 Hunter and Whitman, My Ouni Science Problems, Unit 4 

 Lake, Harley, and Welton, Exploring the World of Science, 



Chaps. 6, 7 

 Pieper and Beauchamp, Everyday Problems in Science, Unit 



5 

 Powers, Neuner, and Bruner, The World around Us, Chaps. 



6, 7 



Skilling, Tours through the World of Science, Tour 4 

 Van Buskirk and Smith, The Science of Everyday Life Chap. 



5 



Watkins and Bedell, General Science for Today, Chap. 4 

 Webb and Beauchamp, Science by Observation and Experi- 

 ment, Units 1, 3, 4 (parts) 



Wood and Carpenter, Our Environment: Its Relation to Us, 

 Unit 1 ; Our Environment: How We Adapt Ourselves to It, 

 Unit 3; Our Environment: How We Use and Control It, 

 Chap. 6 



Special references 



Knox, All About Engineering 



Lynde, Home Waterworks 



Williams, How It Works 



Williams, Romance of Modern Engineering 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. An understanding of modern methods employed 

 to distribute and handle water. 



2. Skill in repairing leaky faucets. 



3. An appreciation of the extensive uses of water 

 in home and community life. 



4. A knowledge of modern sanitary methods em- 

 ployed to dispose of sewage. 



TEST OF MASTERY OF THE TOPIC 



In your notebook complete the statements and answer the 

 questions. 



1. What are the two most common types of faucets? 



2. How does each type of faucet work? 



3. What is the function of a water trap? 



4. When the faucet is turned on, why does the water run 

 out? 



5. When a faucet leaks, it is usually because 



6. Two safe methods employed by cities to destroy sew- 

 age are 



7. If you were living in a country home not supplied with 



