ACCRA, Sept 12 (The African Portal) – Many experts have raised concerns about the rising turbidity levels in Ghana’s water bodies, largely caused by illegal mining activities that continue to pollute rivers and streams.
Some have even warned that if the menace of illegal mining, popularly known in Ghana as galamsey, is not urgently halted, the country risks importing potable water in the near future.
Officials from Ghana’s water treatment plants have been at the forefront of these calls, urging swift action to end mining activities near water sources. They explain that the increasing turbidity levels compel them to use more chemicals in treating water, which not only poses potential health risks but also creates a heavy financial burden on the state. In some cases, water treatment plants have been shut down entirely because the high turbidity levels made it impossible to process water for human consumption. This raises an important question: What is turbidity, and what are the acceptable levels?
Turbidity is an important indicator of water quality that provides quick and relatively inexpensive information on water safety. It can be measured in settings ranging from small rural systems to large and advanced treatment plants. Turbidity is caused by suspended chemical and biological particles and has both safety and aesthetic implications for drinking-water supplies.
In simple terms, turbidity refers to the cloudiness or haziness of water caused by suspended particles such as silt, clay, organic matter, algae, and microorganisms. It measures how much these particles scatter light; the more particles present, the higher the turbidity. Turbidity is quantified in Nephelometric Turbidity Units (NTU), using specialized instruments that assess water clarity and the amount of suspended solids.
While turbidity alone does not always pose a direct risk to public health, it can signal the presence of harmful microorganisms and serve as an early warning of hazards in the water supply system – from the source to the tap.
For instance, high turbidity in source water may harbour pathogens attached to particles, which can reduce the effectiveness of disinfection. High turbidity in filtered water may point to poor pathogen removal during treatment. Rising turbidity in distribution systems may indicate contamination from biofilms, rust, or breaks in pipelines.
Particles in turbid water act as shields for bacteria and viruses, protecting them from disinfectants such as chlorine or ozone. If not removed effectively, these particles can travel into households, compromising drinking water safety and increasing health risks.
The causes of turbidity are varied. Natural factors include eroded sediments, decaying plant material, and algae blooms. Human activities, particularly illegal mining in Ghana, exacerbate the problem significantly. In addition, aging pipelines can release rust particles or accumulate solids, further increasing turbidity. The result is reduced light penetration in water, which disrupts aquatic ecosystems.
Industries are also affected. Turbidity clogs filters, scales equipment, and reduces the efficiency of heat exchangers. Suspended particles contribute to fouling, which obstructs flow rates and shortens equipment lifespan. For example, in cooling systems, deposits from turbidity can reduce the efficiency of gas turbines, while blockages in pipelines force costly and frequent maintenance.
On October 4, 2024, the Ghana News Agency reported that the Ghana Water Company Limited had managed to improve water quality at the Sekyere Hemang Treatment Plant in the Central Region, reducing average turbidity levels from 14,000 NTU to 9,000 NTU.
According to World Health Organization (WHO) standards, drinking water turbidity should be below 1 NTU before disinfection, as higher levels significantly reduce the effectiveness of chlorination. In low-resource areas, water turbidity should not exceed 5 NTU. Compliance with these benchmarks is critical to ensuring the delivery of safe drinking water.
High turbidity not only makes water appear dirty but also harbours pathogens, reduces sunlight penetration, and damages aquatic ecosystems.
Unfortunately, as illegal mining continues to pollute Ghana’s rivers, many of the machines used to treat water in the country cannot handle extremely high turbidity levels. Water experts warn that most equipment imported for domestic water treatment was not designed to process turbidity levels beyond 100 to 200 NTU.
To safeguard the nation’s water supply, Ghana must address turbidity at its root causes, particularly illegal mining while enforcing standard water quality protocols. This will ensure both industries and households have access to safe, sustainable water.
