CITY WATER SUPPLY 



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made of two or three feet of fine sand spread on top of a 

 foot or two of coarse sand and gravel, with stones at 

 the bottom. As the water soaks through the sand the 

 solid matter the impurities are left on top of the 

 filter bed. The filter bed is underlaid with piping full 

 of holes to receive the filtered water. 



INTERIOR OF FILTERING PLANT 

 Showing the instruments for operating each filter. (Penn'a Water Co.) 



In the slow filtering process the water is pumped to a 

 settling basin in which the heavy sediment sinks to the 

 bottom. From the settling basin it is permitted to 

 flow slowly on the filter beds. For a large city there 

 must be several acres of filter beds. From the filters the 

 water flows into a storage basin where enough chemicals 

 are added to kill the disease germs. 



In the rapid filtering process the water is pumped 

 from the river to the top of a high hill where the 

 filtering plant is located. The amount of chemicals 



