140 



SMALL WATER SUPPLIES. 



The appurtenances of tanks are not numerous. 

 They include the delivery pipe, which should always 

 be turned over the side of the tank in an inverted U 

 shape. The overflow should be i in. larger in dia- 

 meter than the delivery, while the draw-off pipes are 

 screwed into the bottom and have copper straining- 

 roses on them to keep out foreign bodies. An indi- 

 cator board, of the type shown in fig. 103, completes 



Pulleys 

 Bracket 



Scale 



the apparatus. 



Cast-iron tanks are not usu- 

 ally made over 4 ft. deep. 

 All tanks should be covered. 

 This is a precaution too often 

 neglected, with the result that 

 the water gets very foul on 

 top, and not usually being 

 seen continues so for years. 

 The writer speaks with some 

 feeling on this point, as the 

 filthy state of tanks in other- 

 wise well-ordered households 

 has astonished him. The 

 simplest way is by means of 3 in. x 4 in. timbers 

 bolted to the top flanges. These then will support 

 rafters in the same way as wall plates in an ordinary 

 house roof. The covering would be boarding treated 

 with creosote, or covered with lead, and having 

 manholes for admission to the tank. The whole 

 should be capable of easy removal. 



The filtering of water next demands attention. 

 Water when collected in the condition in which it 

 occurs in Nature, with the exception of spring and 

 well water, must be subject to some form of filtration 

 before it can be used for domestic use. 



