High levels of manganese in Cork village's water baffling

Environmental experts are baffled at the cause of high concentrations of a metal in the drinking water of a Cork village.

An audit was carried by the Environmental Protection Agency (EPA) of the water supply to Minane Bridge this summer.

The environmental regulator was alerted by Irish Water to levels of manganese above recommended limits.

Manganese is a natural element, commonly found in groundwater.

It is not regarded as particularly toxic, but it can cause staining problems and, in high concentrations, can cause a bad taste.

A warning notice, ‘Do Not Consume’, was placed on the supply in Minane Bridge on July 20, on the advice of the HSE. It followed complaints from a householder about an unusual odour from the water a week earlier.

Tests carried out by Cork County Council showed samples had a concentration of manganese over 36 times the recommended limit, of 50 micrograms per litre.

An inspection by council officials, of landholdings in the area, found no evidence of any activity that could explain the elevated levels of manganese.

Five further samples, taken on different days in July, also revealed high levels of the metal. The highest had a concentration over 162 times the recommended level.

Irish Water said manganese levels dropped significantly in late July, from up to 7,500 to 730 micrograms per litre, which it attributed to the recharging of groundwater, following a period of rain.

The EPA said monitoring of the Minane Bridge supply was ongoing, in an effort to establish the reason behind the elevated manganese levels.

It pointed out that there were no exceedances of recommended limits for any other elements in the water supply.

Irish Water said that the warning notices were removed after the supply subsequently complied with all current drinking water standards.

A spokesperson said that, in the longer term, the company was exploring options to put in place “a permanent technical solution” to prevent any recurrence of an issue with manganese in the supply.


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