An Open letter to the public of eThekwini Municipality

05 August, 2008 11:00

For the past 40 years, the eThekwini Municipality’s Scientific Services Laboratory has been used to test the quality of sea water off the eThekwini coastline.  These results were also used by the Blue Flag organisation to assess the water quality of our bathing waters.   This laboratory is accredited by South African National Accreditation System (SANAS), which confirms the dependability of its test results.   Furthermore, for many years the municipality has used the Council for Scientific aend Scientific Research (CSIR) to audit its results by conducting independent sea water sampling and testing to confirm the results of our own Scientific Services Laboratory.
 
As indicated previously, the frequency of testing of the water and sand microbiology has been increased to once a week. These results are now available on the durban.gov website at the following address: http://www.durban.gov.za/durban/services/services/water_and_sanitation/water-quality/beaches. This website provides information on all 26 beaches, showing the facilities which are available, the latest water quality test results and a litter index to indicate the cleanliness of each beach.  Until a more acceptable indicator has been found, we will continue to use E. coli and Enterococcus, recognizing the short comings of these indicators.  
 
Signboards are currently being erected on all the beaches, providing similar information on water quality and cleanliness for each beach. This information will also be updated on a weekly basis enabling beach users to make their own choices.
 
Recent test results continue to show compliance with DWAF water quality standards except for a period of a few days after significant storm events at beaches which are close to rivers or stormwater drains.
 
Design and construction work is continuing on the project to install pumps in the major stormwater outfalls discharging onto the central beaches. The municipality remains on programme to commission these installations before the December holiday period.
 
A smoke generating device has been purchased to enable Water and Sanitation to help track down those persons who have illegally interconnected their stormwater and sewerage drainage systems.  We will soon be in a position to use the smoke generator to locate properties where these illegal connections exist and then ensure that action is taken to separate the sewerage and stormwater drainage systems.
 
The Science of Water.

Given that the viruses and other pathogens which cause infection cannot easily and cost effectively be detected in sea water, indicators such as E. coli, Enterococcus and other bacteria are used.  These indicator bacteria are themselves not harmful – in fact the World Health Organisation describes them as “harmless organisms”.   Provided that the indicators which are used have a life similar to that of the pathogens and exist in numbers that are in proportion to the level of pathogens in any sample, they can be used to determine the level of pollution of a water body.  
  
A number of papers exist which show that, in tropical waters, Enterococcus is not suitable for use as an indicator of the existence of pathogens in water because the Enterococci are able to multiply on their own in the favourable environment which exists.   Equally E. coli die off at a rate faster than the pathogens and may therefore under report the degree to which a water body is polluted.  The World Health Organisation, in one of it’s most recent publications entitled “Monitoring Bathing Waters – a Practical Guide to the Design and Implementation of monitoring programmes”, states that “the lack of a strong relationship between faecal indicators and health outcomes in a number of epidemiological studies in warm tropical waters may, in part, relate to the inappropriate nature of E. coli or faecal streptococci as indices of waterborne pathogens in these recreational waters.  In this context an alternative index group, sulphite-reducing clostridia or spores of Clostridium perfringens, have been proposed and are in use in Hawaii.”
 
Epidemiological studies have been undertaken in the past to link the number of indicator colonies present in a specific volume of water, to the level of infection of bathers in contact with the water.  At the time of most of these epidemiological studies, bacteria colonies were grown on media which gave far lower counts of colonies than the modern day media which are more sensitive and which give higher colony counts.  Recent studies indicate that the bacteria colony counts detected using more sensitive techniques used today, can be 50% to 100% higher than those detected in the past. This can result in water that was considered safe before, now being considered unacceptable merely because of more sensitive detection methods.

 
N A Macloed
Head: Water and Sanitation