Manganese in Borehole Water: The Other Staining Metal

Black or dark-brown staining around taps, on toilet bowls, and in your laundry is one of the more alarming things a new borehole owner encounters. Iron gets most of the blame for discoloured borehole water, but manganese is often the real culprit — or a co-conspirator. It behaves differently from iron, responds to different treatment, and carries its own health considerations under South Africa’s drinking-water quality standard, SANS 241 (2024 edition). If your water is leaving dark marks, this article explains what you are likely dealing with and what to do about it.

What manganese is and why it turns up in boreholes

Manganese is a naturally occurring metal found in rock and soil across much of South Africa, including the dolomitic and sedimentary geology common around Johannesburg. As groundwater moves through these formations over time, it dissolves manganese from the surrounding material. The result is water that looks perfectly clear when it comes out of the tap — manganese in dissolved form is colourless — but turns dark when it contacts oxygen, whether in your pipes, your geyser, or on your sanitaryware.

This is the key difference from iron: iron tends to stain reddish-brown, while manganese produces darker stains ranging from grey to near-black. Many boreholes carry both, which means staining can be a complex mixture of colours. Testing is the only way to know what you are dealing with and in what concentrations.

What SANS 241 says about manganese

SANS 241 (2024 edition), the South African standard for drinking-water quality published by the South African Bureau of Standards, sets both aesthetic and risk-based limits for manganese. The aesthetic limit — the point at which staining and taste become noticeable — sits below the risk-based limit, meaning your water can look and taste unpleasant well before it reaches concentrations that raise health flags. The standard distinguishes between these categories deliberately, so a result that exceeds the aesthetic threshold does not automatically mean a health emergency, but it does warrant action.

At higher concentrations, manganese is associated with neurological concerns, particularly with long-term exposure. The National Institute for Communicable Diseases (NICD) and international health bodies recognise manganese as a substance requiring monitoring in drinking water. For this reason, a professional water test — not a home colour kit — is strongly recommended before you draw any conclusions or invest in treatment.

The test-first principle

Borehole water is not a uniform product. Two boreholes on the same street can have meaningfully different chemistry. A proper laboratory analysis will tell you:

• The concentration of dissolved manganese (and iron, which often accompanies it)
• The pH of your water, which affects how treatment systems perform
• Whether other contaminants — nitrates, bacteria, turbidity — are also present

This matters because treatment systems are not interchangeable. A system sized and specified for one set of results can perform poorly against a different water profile. The principle here is straightforward: test first, treat second. Spending money on equipment before you have a test result is a common and avoidable mistake.

For a broader picture of what borehole ownership involves — including water quality obligations — the borehole drilling guide covers the full process from site assessment through to commissioning.

How manganese treatment works

Dissolved manganese cannot simply be filtered out of water in its dissolved state — it has to be converted to a solid particle first, and then removed. The process has two main stages:

Oxidation converts dissolved manganese into its insoluble form. This can be achieved through aeration (exposing water to air), chemical oxidation using chlorine or potassium permanganate, or catalytic media that promotes the reaction without additional chemicals. The right approach depends on your manganese concentration, your water’s pH, and whether iron or hydrogen sulphide are also present.

Filtration then removes the oxidised particles. Greensand and birm are filtration media specifically designed for manganese and iron removal. A correctly specified backwashing filter will capture the oxidised particles and periodically flush them to drain.

Sequencing matters: if the oxidation stage is insufficient, the filtration stage is overwhelmed. If the filter is undersized for your flow rate, treated water quality will be inconsistent. This is why system design should follow from a test result, not precede it.

If you have a test result in hand and want to know what a properly specified system should cost, compare three free installer quotes — vetted local suppliers, no obligation.

What treatment systems typically cost

As a rough guide, a standalone manganese-and-iron filtration unit for a typical Johannesburg home — covering oxidation media and a backwashing filter vessel — might form part of a broader borehole water treatment package. Complete borehole systems including pumping, storage, and treatment typically run R60,000–R100,000 for most residential installations in Johannesburg, though the full range is R40,000–R150,000 depending on depth, yield, and treatment complexity. If you already have a working borehole and need only the treatment component, costs will be lower — confirm current pricing through quotes, as equipment and installation costs vary between suppliers.

For context on how to read and compare those quotes sensibly, the article on how to compare water quotes walks through what to look for and where quotes commonly differ.

Ongoing maintenance you should plan for

Manganese filtration systems are not fit-and-forget installations. Backwashing filters need periodic regeneration or media replacement, and the frequency depends on your manganese load. Key maintenance considerations include:

Item	Typical frequency	Notes
Backwash cycle	Automatic, often daily	Set by a timer or pressure differential
Media inspection	Every 1–2 years	Fouled or exhausted media reduces performance
Water re-test	Every 12–24 months	Groundwater chemistry can shift over time
Pre-filter sediment cartridge	Every 3–6 months	Protects downstream media

Retest intervals matter because borehole water is not static. Seasonal rainfall, changes in local groundwater abstraction, and the age of the borehole can all influence what comes out of the tap over time.

When to call in a professional

If you are seeing dark staining, start with a laboratory water test from an accredited facility. Once you have results, discuss them with an installer who can explain the treatment logic — not just quote you a package. Ask what happens if your manganese concentration changes over time, how the system will be maintained, and what the warranty covers on media and equipment. A good installer will welcome those questions. One who cannot answer them is worth reconsidering.

Ready to get your water assessed and treatment options priced? Request quotes from three vetted Johannesburg installers — no obligation, and no pressure to commit.

The bottom line

Manganese in borehole water is a solvable problem, but it is not a one-size-fits-all fix. The dark staining is a signal worth taking seriously — both for the nuisance it causes and for the health context that SANS 241 and bodies like the NICD attach to elevated manganese concentrations. A laboratory test is the non-negotiable first step. From there, a correctly designed oxidation-and-filtration system, installed and maintained by a competent operator, will reliably bring manganese within acceptable limits. Get the diagnosis right before you commit to the treatment.