WATER FILTRATION. XV. 



Subsiding and storage reservoirs for unfilterecl water. 

 Available capacity in gallons per million gallons supplied : 



Gallons Gallons 



Chelsea ... 12,200,000 New River ... 5,120,000 



East London ... 21,600,000 South wark and 



Grand Junction 3,500,000 Vauxhall ... 4,300,000 



Lambeth ... 6,180,000 West Middlesex 5,960,000 



Filtering area in acres per million gallons of the average 

 daily supply : — 



Actgs .Actp^i 



Chelsea 0*58 New River 0*43 



East London ... 0*64 Southwark and Vauxhall 0*61 



Grand Junction ... 1*13 West Middlesex ... 0*72 



Lambeth 0*50 



Average rate of filtration per square foot per hour : — 



Gallons. Gallons. 



Chelsea 1*75 New River 2*25 



East London 

 Grand Junction 

 Lambeth 



1*33 Southwark and Vauxhall 1*50 

 1*63 West Middlesex ... 1*25 



1*80 



From a description of the water supply to Edinburgh, 



published by the Edinburgh Council, filtering material is, 



Broken stone, granite whinstone 3 feet 3 inches 

 Gravel size of walnuts ... 

 Gravel size of beans 

 Coarse sand 

 Fine sand ... 



Total 



Average rate of filtration 3*08 gallons per square foot per 

 hour. This is excessive. 



Liverpool — Vyrnwy Water. 



Second Installation. 

 Gravel ... 1 foot inch Gravel ... 1 foot inch 

 Sand ... 2 „ „ Sand ... 2 „ 6 „ 







n 



6 



11 







11 



6 



11 







11 



6 



11 



1 



11 



6 



11 



6 



11 



3 



11 



Total ... 3 „ „ Total ... 3 „ 6 „ 



Average rate of filtration per square foot per hour, 2*2 

 gallons. 



