viii CONTENTS 



CHAPTER XX. 

 FARM WATER- WORKS. 



Convenience of running water. Methods of supplying running water. .Gravity sup- 

 plies from wells. Gravity supplies from springs. Gravity supplies from reser- 

 voirs. Gravity supplies from elevated tanks. Pneumatic or pressure tanks. 



CHAPTER XXI. 

 COMPOSITION AND TESTING OF WELL WATERS. 



Purity of rain water. Sources of mineralization. Hardness of well waters. Water 

 for boilers. Harmless and harmful ingredients. When well waters should be 

 suspected. Analyses and bacteriological examinations. Simple sanitary tests. 



CHAPTER XXII. 

 PURIFICATION OF WATER SUPPLIES. 



Necessity of treating the waters. Color. Turbidity. Odor and taste. Iron. 

 Temporary hardness. Permanent hardness. Alkalinity. Algae. Bacteria. 



