Recent water quality tests reveal continued fluctuations in E. coli levels across various points of the Vaal River, according to Rand Water’s latest sampling report from Wednesday, 29 January.

The data shows particularly concerning readings at several monitoring points, with some areas showing significant risk for gastrointestinal disorders.

Vaal River critical water quality fluctuations

The latest sampling data from 29 January shows concerning E. coli readings across multiple points along the Vaal River system.

On sample nine near Village Manor, the readings reached an alarming 72 700 E. coli counts per 100ml.

However, while this may be a high number, last week’s readings were much higher, having skyrocketed to 111 990 E. coli counts per 100ml.

Meanwhile, just after Ascot Bridge, measurements showed 15 150 counts per 100ml, indicating a high risk for gastrointestinal disorders. This was almost a triple E. coli count increase from last week’s, where it was at 5 380 counts per 100ml.

In contrast, some areas showed lower concentrations, with point seven near Vaalview Aquatic Club recording just 4 counts per 100ml.

Blue-Green algae levels also showed significant variation across the river system.

The highest reading was near Loch Vaal (at sample eight of Blue Green Algae) with 51 525 counts, while sample nine near Village Manor recorded 12 429 counts.

Despite these elevated numbers, most areas maintained moderate risk levels, according to the monitoring criteria.

Algal pigments, measured as Chlorophyll-a levels, ranged from as low as 6 near the Railway Bridge to as high as 84 at Loch Vaal, demonstrating the varying water quality conditions throughout the reservoir system.

ALSO READ: Water and Sanitation dept warns of cholera detection in Vaal River

Understanding E. coli risks

E. coli contamination in water bodies typically stems from various sources, including human and animal waste, agricultural runoff, sewage system failures, and increased water flow during heavy rainfall.

When untreated river water is consumed, it can lead to skin irritations, infections, and intestinal disorders.

Vaal River/ Dam water treatment and safety measures

Rand Water maintains comprehensive quality control measures, including testing for various contaminants.

“The drinking water supplied by Rand Water from the Zuikerbosch Water Treatment Plant complies with the South African National Standard requirements for all these microbiological organisms,” the utility confirmed.

Rand Water also emphasised that their distributed water remains safe for human consumption as it is drawn directly from the Vaal Dam and not the river.

“The drinking water supplied from Zuikerbosch WTP is safe for human consumption.”

ALSO READ: High levels of E.coli still found in these parts of the Vaal River

Current Vaal Dam water levels

As of Monday, the Vaal Dam stands at 61.30% capacity, marking a significant recovery from levels below 30% recorded last year.

The dam’s improved status can be attributed to heavy regional rainfall and strategic water management, including additional inflow received from the Grootdraai Dam when it opened two sluice gates in January.

Current measurements show water flowing into the Vaal Dam at 40.4m³/s, while releases are maintained at 16.8m³/s. Downstream, the Vaal Barrage maintains a level of 7.5m, with an outflow rate of 44.7m³/s.

The water temperature in the system is recorded at 25.2°C, indicating typical summer conditions.

ALSO READ: Road to recovery: Here’s what level the Vaal Dam is currently at

Rand Water monitoring and quality assurance

The utility said it has implemented “an intensive water quality monitoring programme” that includes testing for E. coli, protozoan parasites, and viruses.

According to their national standards, “E. coli should not be detected in drinking water”, a requirement that Rand Water confirms they consistently meet in their treated water supply.

This ongoing monitoring becomes particularly crucial given the fluctuating E. coli levels observed in the river system. It ensures that while raw water sources may show contamination, the treated water reaching consumers meets all safety standards.

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