Our Letter Box.

Taranaki Daily News, Volume XLVII, Issue 7736, 11 February 1905, Page 4

Our Letter Box.

(We are not responsible for opinioaa expressed by correspondents.) SEPTIC TANKS. (To the Editer.) Bir, —Your correspondent (Mr Wastney) writes of the mysteries of the septic tank system, and says few jMople fcriow anything about it. If fttis is so, the following brief and non-technical description may be of interest to him and others. I may premise that the inventor of the .septic tank system for the disposal of sewage is Mr Donald Cameron, the city surveyor of Exeter, a personal friend of mine, and it was from his own lips I gathered the following Information. A septic tank properly constructed consists simply of an underground air tight, and light tight, tank having a supply, and an exhaust pipe, both near the bottom and bath provided with stop cocks. This having been constructed, the sewage is turned into it till the tank is full, when the supply is diverted teto another tank. Tank No. 1, being now full, is allowed to rest undisturbed for a given time (exactly how long I am now uncertain, but I think it is from 48 to <SO hours). During this time the bacteria or microbes present, under tlie favourable conditions of darkness and quietude, develop at an enormous rate, eat up ■tl the solid matter, then eat each other, and ultimately die of starvation. At the end of the given time the exhaust pipe is turned on and the ta«k emptied of its contents —which should now be a colourless and odourless liquid, allowed to flow away. This is briefly the whole mystery of the septic tank. The requisite conditions are darkness and quietude while the bacteria develop, It follows that no single tank can fulfil these conditions. Two or more must be provided, according to the amount of sewage to be disposed of. —I am, etc., C. E. BAKER.