HAWERA WATER SUPPLY

Hawera Star, Volume XLV, 20 February 1926, Page 4

HAWERA WATER SUPPLY

HIGH STANDARD OF PURITY.

AN ANALYSIS MADE. DAIRY" SCIENTIST’S FINDINGS. Entirely favourable are the results of an analysis of the Hawera town water supply which has been carried out by Mr P. O. Veale, 8.A., scientist in charge of the local Dairy Research Laboratory. Mr Veale finds the borough water to be of the very best quality, judged from the chemical point of view; and he remarks on its superiority over the supply in Auckland city. ■Some time ago the suggestion, was made through the columns: of the Star that some qualified person should undertake an analysis of the Hawera water, and publish the results for the benefit of the .public., Mr Veale has now had the opportunity of performing the necessary experimental work, and he has generously placed' his findings at the. disposal of the Star, as follows: Parts by weight in 100,000 of wu-ter Suspended matter not measarable Dissolved solids Free and' saline ammonia .... 0.0007 Albumenoid ammonia 0.0055 Total nitrogen as ammonia .. 0.0062 Chlorine as sodium chloride .. 0.9 Oxygen absorbed from potassium permanganate — (1) In three minutes 0.033 (2) In four, hours 0.048 Mr Veale says that these figures indicate a very satisfactory quality in the public water supply, and he has gone to some trouble to expalm their significance. From a health point of view, says ■‘the analyst, the suspended matter and 'dissolved soHds in any public water supply are of trifling importance, and usually cause no trouble. The suspended solids can easily be removed by fil■tration, while the greater part of the dissolved matter consists of inorganic salts and mineral substances which might even be slightly beneficial to the human system. However, as their presence in water offends, the tastes of the majority of consumers, it is pleasing to note a complete absence of ponderable suspended matter, and a low proportion of dissolved solids. Quite a number of satisfactory public water supplies contain as much: as 30 to 60 parts per 100,000 of dissolved) solid matter. • The ammonia in natural water is derived almost exclusively from animal contamination, and! its amount naturally varies. The free and saline ammonia is quite innocuous, and represents the amount of contamination from which the water has successfully recovered, because ammonium compounds invariably result from the dec composition of animal matter. The Hawera water supply value for this figure may be considered quite satisfactory, and, in fact, from five to ten times the amount could! be present without being a cause, for any, concern. The albuminoid! ammonia is evolved •from disintegrating . nitrogenous organic matter present in the water, and naturally should not have a very high value. Waters of very great organic purity may contain up to 0.0041 parts per 100,000 of albuminoid ammonia, shut any value between this and 0,0082 •is considered quite satisfactory. Mr Veale has no doubt that, in the winter months, the Hawera supply will he promoted from the ‘^satisfa'Ctory* 5 to the 11 extremely pure ’’ class. ... Chlorine, present as sodium chloride >or common salt, is frequently derived from animal excreta, but may also be the result of the geologic formation m which the. source of the supply is found: In any case, it is quite harmless, and 1-2 parts per 100,000' are very common, instead! of the 0.9 found m Hawera water. The figures for the absorption ox oxygen from potassium permanganate in three minutes and in four hours indicate the amount of oxidisable organic matter present, and the difference serves as a measure of the amount or putrefaction which is occurring m the water. Small quantities of vegetable matter cannot be avoided, even m the most carefully shielded sources or reservoirs' and waters of the greatest purity may absorb up to 0.05 parts or oxygen per 100,000 in four hours. From this it will be seen that the Hawera supply qualifies for the highest the results of his tests, which were the standard ones employed for the examination of public water •supplies, Mr Veale comments: It will be seen that Hawera water at present •must ‘be considered of the very best quality from the chemical point ol •view, and I might state tnat‘one o 'the first tilings I noticed on taking up my residence in this town was the werv favourable comparison made by the' clear water of Hawera with tne supply of Auckland. 1