Manganese
What you need to know.
Source
From the ground up.
Manganese in drinking water typically originates from natural contamination at the water source. As the 12th most abundant element in the earth’s crust, Manganese is a common component of many surface and groundwater supplies, with the manganese leaching into the raw water from the surrounding soil and rock.
Manganese is often found in higher concentrations when the water supply primarily exists in a low oxygen environment, for example, water extracted from aquifers or from the bottom of settled lochs. In Scotland, manganese contamination is more commonly observed throughout the South and West regions.
In some cases, manganese contamination can persist after treatment due to the buildup of manganese deposits within the distribution system. Usually the introduction of water filtration solves this issue, but in severe situations, cleaning or replacement of the effected water pipes and tanks may be required in addition to the treatment of the water.
Key indicators
Black staining on sanitaryware.
The most common visual indicator of manganese contamination is black/brown staining, which can appear on bathroom appliances, plumbed fixtures and laundry.
Occasionally, manganese deposits which have accumulated on the walls of pipes and tanks can become dislodged, introducing a fine, black particulate into the water. These deposits are usually observed around water drains or within the water itself. Higher concentrations of manganese can even discolour the water brown.
Aside from staining, high levels of manganese can also give your water a metallic taste.
Regulatory limit
Maximum level = 50μg/l
The regulatory limit for manganese in drinking water is 50 micrograms per litre (50μg/l).
While the World Health Organisation (WHO) provides a health based guideline value of 400μg/l for manganese in drinking water, the lower regulatory limit ensures that the water remains aesthetically acceptable to drink. Aesthetic acceptability considers the taste, odour and overall appearance of the water.
In relation to manganese, the limit was largely selected based on the evidence that manganese concentrations above 50μg/l have an increased likelihood of coating the internal components of UV (ultra-violet) disinfection units in a fine particulate, reducing the ability of the unit to neutralise the microbiological contaminants (e.g. viruses and bacteria) in your water.
Testing
Seasonal changes.
As a raw water contaminant that comes from soil and rock, manganese levels can change seasonally, especially if local activities heavily disturb the ground. An example of this could be new forestry projects in your area or nearby agricultural work. An understanding of these changes through regular testing can ensure that your water filtration treatment remains effective over the long term, and alterations can be made if necessary.
In addition to natural fluctuations at the source, water tests can help to identify any issues with manganese buildup in the distribution system. Historic manganese deposits that have accumulated in tanks and pipes prior to water treatment can be very difficult to simply flush from the system, perhaps requiring specific cleaning procedures, use of chemicals or complete replacement.
