Following the recent rains, Oudtshoorn is currently experiencing a deterioration in water quality with regard to turbidity, which is the measurement of colloidal suspended solids in water (i.e. an indication of particles suspended in the water).
The high intensity rainstorm (75 mm in less than two days) in the catchment area of the Raubenheimer Dam caused flash floods resulting in muddy water entering the dam. According to national standards, the aim is to keep turbidity below 1 NTu (NTu being the measurement unit for turbidity). Under normal conditions the turbidity of the water from the dam ranges between 0.5 and 3 NTu, which is still acceptable. Directly after the recent rains, the turbidity increased to above 40 NTu, but has since decreased to 30 NTu. It can thus be seen that the quality is improving and should return to normal within a few weeks.
The increase in turbidity (i.e. the presence if small particles in the water) are generally not regarded as harmful. It can however compromise the effectiveness of the disinfection. The quality of the water is monitored on a regular basis and tests done after the recent rain still indicate no presence of E.Coli (an indication of possible harmful bacteria being present). It is however recommended that water for drinking purposes be boiled until the water quality is back to normal.
The only water treatment taking place at the Raubenheimer Dam is disinfection by means of chlorination. No water treatment plant exists and the thus no filtration of the water is done. This has been the situation since the dam was built in the early 1970’s. Due to the exceptionally high quality of raw water this has been deemed acceptable for most of the time. However, following heavy rainfall, the water quality does deteriorate and the situation can continue for a few weeks.
To address this periodic deterioration of the water quality, a treatment works is needed. This option has been investigated numerous times by the Municipality with the latest report compiled in 2014, recommending a filtration plant to the value of approximately R100 million to be constructed. This is now again under investigation and funding possibilities are being pursued.
Issued by the Oudtshoorn Municipality’s Communication & Media Services on Monday, 02 December 2019