WATER SUPPLY 221 



The filter is easily kept in good working order. There is a 

 handle at the side by means of which the sand can be thoroughly 

 well stirred up to prevent a scum accumulating on the surface 

 and impeding the free passage of water. The manager should 

 see that this is well turned round at the end of each week. 

 Once in six months the sand should be changed, the old sand 

 being emptied out and fresh, well-washed sand put into the 

 cylinder. This is a very simple task and easily executed. 

 These filters give great satisfaction on many rubber plantations. 



When well water is used for drinking or cooking purposes 

 every possible precaution should be taken to ensure and pre- 

 serve the purity of supplies. No well should be excavated 

 within less than 100 to 120 feet of coolie lines or latrines. It is 

 better to erect pumps to pump up fresh supplies than to allow 

 coolies to let down buckets and draw water for themselves. 

 If this is not done, it is hard to keep impurities from entering 

 the wells. The deeper the wells are dug the less likely are the 

 supplies to be contaminated with surface waters from drains. 



