84 WATER SUPPLY FOR DOMESTIC USE. 



cheaper appliance for this purpose, some years ago. It con- 

 sisted of a small galvanised iron vessel divided into two com- 

 partments, and placed on a pivot over the inlet opening of the 

 tank. As the water flowed it was discharged over the tank 

 until sufficient had collected in the second chamber to tilt the 

 vessel over the inlet. This simple, cheap, and efficient appa- 

 ratus has not, as far as my observation goes, ever been brought 

 into even moderate use in this city or suburbs. Water collected 

 from galvanised iron roofs and stored in galvanised iron tanks — 

 the usual practice here — has a decided metallic taste, which is 

 disagreeable and likely to engender dyspeptic troubles in those 

 who drink much of it. Filtration through charcoal removes this 

 taste. 



Distribution. 



The distribution of water to communities is effected on two 

 systems — the constant and intermittent. The former is by far the 

 most satisfactory and sanitary method, as it does not require the 

 use of storage tanks, which are objectionable on account of the 

 difficulty in keeping them free from deposit of matters held in sus- 

 pension in the water, and from dust, insects, decaying animal and 

 vegetable matter, &c. With an intermittent supply, when the 

 water is turned off at the main, and is still being run off at the 

 lower levels, a partial vacuum is created in the pipes at the 

 higher levels, and ground water and gases, if not actual sewage, 

 may be sucked into the pipes through fissures or imperfect joints, 

 which would be distributed to the consumers with the water 

 when turned on again, and give rise to a fertile source of disease. 

 The- constant system is the one which is now being almost 

 universally adopted. The water for drinking and cooking should 

 be drawn direct from the main, and if delivered pure, as it 

 undoubtedly ought to be, would suffer little risk of contamina- 

 tion at the hands of the consumers. 



Quality of Water and Sources of Pollution. 

 Physical characters. — Good drinking water should be clear, 

 colourless, or slightly blue, free from odour, except the ozonic 

 odour of spring water ; aerated, fresh to taste, should contain 

 no suspended matter and deposits, and deposit no sediment on 

 standing, and should not become offensive to smell when kept 

 for 24 hours in a warm place. 



