Work ongoing to reduce chance of toxic pollutant entering the water supply in Maidenhead

South East Water said it is working on measures to further reduce the chance of toxic chromium entering the water supply - seven years after warning the pollutant posed 'a significant risk.'

The Drinking Water Inspectorate provides independent reassurance that water supplies in England and Wales are safe and drinking water quality is acceptable to consumers.

It received a report from South East Water in November 2017 stating there has been a ‘significant risk’ of supplying water that ‘could constitute a potential danger to human health’ or could be ‘unwholesome.’

This relates to Maidenhead Treatment Works, also known as College Avenue Treatment Works – and specifically risks relating to chromium.

Chromium pollution is known to be a significant environmental threat, severely impacting the environment and natural resources, especially water and soil.

Excessive exposure could lead to higher levels of accumulation in human and animal tissues, leading to toxic and detrimental health effects.

As such, South East Water has been called upon to perform increased monitoring for chromium in the catchment and at Maidenhead Treatment Works.

One solution is looking at water ‘blending’. Mixing water from different natural sources means that the level of chromium in the drinking water meets the legal safety limits.

The company also has to partake in ongoing investigation to identify chromium risks within the catchment and continuously assess the danger posed by it.

So far, chromium water treatment pilot trials have been carried out to identify a suitable treatment option.

South East Water must provide a report annually by January 31 each year.

Dr Neil Hudson, head of water quality at South East Water, said: “We carry out more than half a million tests on our water each year to ensure that the water we supply is of the highest quality.

“We are independently assessed by the water quality regulator, the Drinking Water Inspectorate, to ensure we continue to maintain these exceptionally high standards.

“There is a regulatory requirement for all drinking water in England to contain less than 50 micrograms of total chromium and we have a duty to ensure that chromium 6 in drinking water is below 3 micrograms per litre.

“We meet these requirements and are committed to ensuring our drinking water quality is maintained and enhanced.

“Following comprehensive investigations of the Maidenhead catchment area, a history of sites and businesses that use chromium has been identified.”

Possible uses include metal plating, stainless steel manufacturing, pigments and dyes, wood preservation, tanning leather, electronics and aerospace industries.

Dr Hudson continued: “Although the risk of this moving into the groundwater source is low, we are working in partnership with the local planning authority and the Environment Agency to implement measures to reduce this risk further.

“[This includes] the potential to install in-situ chemical reduction underground barriers in the aquifer.

“We have also designed an ion exchange plant as an additional barrier to mitigate risk, if required.”

An ion exchange water treatment system is a specialised technology used in wastewater treatment to remove dissolved ions and contaminants from water.

This plant is subject to a planning application that has been submitted to RBWM and is currently awaiting determination, Dr Hudson said.

He continued: “We regularly report the results of ongoing monitoring to the Drinking Water Inspectorate and our next annual report is due to be submitted in January.”