I thought I have had written enough on issues pertaining to the privatisation of the nation's sewerage services in general and septic tanks in particular. I believe I have already provided sufficient information and details on the working and maintenance of septic tanks in many of my letters published earlier in the newspapers. I am therefore astonished to come across yet another letter by IWK "Septic tanks need to be desludged for everyone's good" (NST, May 25 1998) which virtually took us all back more than two years ago when I first started writing on this subject.

As in many of IWK's previous letters on this subject, this latest one contains many half-truths and/or baseless assertions. Let's take a look at some of the more blatant ones.

• "Septic tanks are mere storage tanks and----. As sewage enters the septic tanks, it separates into sludge, which-----." Actually, sewage in a septic tank undergoes anaerobic decomposition (biological action by bacteria in the absence of oxygen). The sludge is the by-product of this biological action.

• "---effluent which is partially treated and discharged into the perimeter and/or monsoon drains." A proper septic tank would have a granular filter bed or a soak-away pit. The partially treated effluent from the tank passes to the filter bed where further biological decomposition takes place before the final effluent is discharged into the drain.

• "----public drains in many of the older housing estates that use septic tanks-----. The drains are basically open sewers and filthy." This statement is too generalised and made without any basis. I live in an area of Petaling Jaya, which is about 30 years old, and all residences here have individual septic tanks. I would like to invite the writer to inspect the drains here and see for himself whether they are just open sewers and filthy.

• "Further, septic tanks that have not been desludged for a long time may crack and-----." Technically, this statement is most ridiculous. An engineer would know that if an under-ground septic tank has not been properly designed or constructed, it would crack whether it is empty, full of fluid and/or sludge. Perhaps, the writer may not be an engineer; but if he is writing a technical subject on behalf of IWK, surely advice from a competent engineer in his organisation should have been first sought.

• "These rates include the cost of desludging, removing and treating the septic tank sludge." Treatment of sludge requires adequate and proper storage, thickening, conditioning, and dewatering facilities. Can IWK honestly say that they have now installed these for the treatment of sludge from septic tanks? Putting septic tank sludge into oxidation ponds and other treatment plants together with other incoming sewage is not sludge treatment!

A septic tank is the most elementary form of domestic sewage treatment facility. As a custodian of the nation's sewerage services, IWK should have no excuse of not knowing how a simple septic tank works. In spite of more than 5 years into the privatisation concession, it is hard to fathom why IWK is still making such false and baseless statements.

Note: The above article was sent to NST on 30 May 1998, but was not published.