Raw water is inherently unstable. The same source can shift in turbidity, microbial load and dissolved content within hours. If that variability is not controlled, it starts to affect everything downstream, from process performance to product quality.
If you’re watching the video, this article walks through what is happening at each stage of the treatment process. Each step is there to remove a specific risk, whether that is suspended solids, dissolved contaminants or microbiological load. What matters is how consistently those risks are removed, not how the water looks at any single point.
When you’re responsible for the plant, the process itself is rarely the problem. The pressure comes from keeping it stable when the incoming water is not. That is where treatment design and control become critical.
What are SANS 241 standards?
SANS 241 sets the minimum standard for drinking water quality in South Africa. It defines the acceptable limits for microbiological, chemical and physical parameters that determine whether water is safe to drink. You can refer to the public draft of the SANS 241 and the standard and supporting material from the Water Research Commission for the full framework.
From a public health perspective, those limits are essential. Water must be free from pathogens and harmful contaminants.
In an industrial environment, SANS 241 becomes your baseline for incoming water. Even within that baseline, variation can still affect cleaning performance, production stability and downstream processes. You often see the impact long before it becomes a compliance issue.
In many facilities, meeting SANS 241 alone is not enough. Food and beverage manufacturers, in particular, tend to work to tighter internal specifications.
To meet those requirements, additional treatment steps, such as reverse osmosis, are used to reduce variability and tighten control over the final water profile.
How is potable water produced?
To understand how potable water is produced, we need to start with the raw source.
Dam water, for example, typically carries suspended solids, fine clay, organic matter and microorganisms.
In some cases, visibility in the raw water may be as low as 0.5 to 1 metre.
Turning that water into a safe and reliable supply requires a controlled treatment process. Each stage removes a different category of contamination and reduces a specific risk. We see the water go from visibly polluted to microbiologically safe.
The four core steps in potable water treatment
Step 1: Clarification
The first major step is clarification, where bulk solids are removed. The goal is to stabilise and condition the water before it reaches downstream processes.
Coagulants and polymers are dosed into the incoming water.
Polymers are long-chain organic chemicals that help fine suspended particles bind together. These chemicals encourage tiny particles, especially clay, to clump into larger masses called flocs.
Once those flocs become heavy enough, they settle to the bottom of the clarifier tank.
Clarification delivers the first visible improvement in water quality. It also reduces the solids load moving forward. If clarification is unstable, it places immediate pressure on filtration and disinfection.
Step 2: Sand filtration
Once clarified, the water passes through sand filters. The purpose here is to physically strain out the remaining fine particles that did not settle in the clarifier.
Sand filtration further improves water clarity. In many cases, visibility can increase to 2-3 metres. Visually, the water is dramatically improved from the raw intake.
But appearance can be misleading. Clear water is not automatically safe water.
Step 3: Disinfection
Even after sand filtration, dangerous microorganisms may remain.
Bacteria such as E. coli are extremely small, around 0.2 microns in size, and can pass through conventional filtration barriers. That means filtration alone does not control biological risk.
Disinfection is the stage that addresses the biological risk that filtration cannot remove on its own. Chlorine is added to destroy harmful pathogens and make the water safe for human use.
If disinfection is not properly controlled, microbiological risk can carry straight through the system.
For broader health guidance, see the official WHO Guidelines for drinking-water quality, 4th edition, incorporating the 1st addendum and the WHO Drinking-water quality guidelines.
Step 4: Storage and contact time
After chlorination, the water is transferred into storage reservoirs. These reservoirs are part of the treatment process. Chlorine needs contact time with the water to work effectively.
If water moves too quickly through the system, the disinfectant may not have enough time to achieve the intended microbiological kill.Chlorine also provides residual protection as the water moves through the distribution system. That ongoing barrier is central to potable water treatment.
Adapting the process for complex water sources
The core treatment sequence is well established, but not every water source is equal. Effective system design depends on understanding the specific source water challenge and applying the right additional process steps where needed.
Mountain water
In mountainous regions such as George or Swellendam, raw water is often relatively low in conventional pollution but heavily stained with natural organic colour.
To deal with this, treatment systems may include advanced oxidation or activated carbon as part of the broader process sequence.
Borehole water
Facilities that use borehole water to reduce dependence on municipal supply will face a different set of challenges.
Depending on the geology, you may see elevated levels of salinity, iron, manganese, or fluorides.
In these cases, reverse osmosis or targeted oxidation steps may be required to bring the water to a potable standard.
No serious treatment solution should be designed as a one-size-fits-all system.
If your operation depends on stable water quality, treatment design plays a direct role in risk, uptime and consistency.
Talk to an expert today to discuss the right solution for your source water, treatment requirements and operational goals.
FAQs:
What is drinking water treatment?
Drinking water treatment is a multi-stage process used to remove suspended solids, harmful chemicals, and biological pathogens from raw water, making it safe to drink and reliable for industrial use.
How is potable water produced?
Potable water is produced by removing visible solids first, then finer particles, then microbiological risk through disinfection and contact time.
What are SANS 241 standards?
SANS 241 is the South African National Standard for potable water quality. It defines the microbiological, chemical and physical limits water must meet to be considered safe for drinking. For context on the standard and its current public reference material, see the available SANS241 draft document and the WRC explainer page.
What are the steps in potable water treatment?
The main steps are clarification, sand filtration, disinfection and storage for chlorine contact time. Depending on the source water, additional processes such as activated carbon, advanced oxidation or reverse osmosis may also be required.
