The unusual discolouration was reported near a treatment works in Ponthir, raising fears of pollution among residents who use the area for fishing and recreation.
Images and videos shared online point to the issue persisting for several months on land off Candwr Road.
Water with a strong orange tint seen near a popular local fishing spot in Ponthir. (Image: Supplied)
One resident, who reported the issue to the Argus, said: “You get people fishing here and occasionally children swimming. There are lots of weeds so it’s not safe to swim in but with school holidays now who knows.”
The same orange hue was captured in images taken more than a month ago, suggesting an ongoing issue.
After investigating, Natural Resources Wales (NRW) said they do not believe this is a pollution incident.
A NRW spokesman said: “We have spoken with Dŵr Cymru Welsh Water regarding the photos and video shared with us.
“Based on the information provided, we do not believe this is a pollution incident.
“The discharge into the lagoon is part of the treatment process within Dŵr Cymru Welsh Water’s Court Farm Water Treatment Works and is part of normal site operations.”
Water with a strong orange tint seen near a popular local fishing spot in Ponthir. (Image: Supplied)
Welsh Water confirmed that the colour comes from iron content in untreated water being recycled as part of the treatment process.
A spokesman said: “The footage shows untreated water being returned to the reservoir.
“The water is being recycled from our processes at the Water Treatment Works and does have a level of iron content which is the discoloration observed.”
Water with a strong orange tint seen near a popular local fishing spot in Ponthir. (Image: Supplied)
He explained that the recycled water comes from filter washing processes, which help conserve water and protect the environment.
He said: “The water from the reservoir is transferred to our Water Treatment Works where it is treated to the high standards set by our regulators.
“Drinking water quality standards in Wales are among the best in the world.”
Iron naturally occurs in water and soil, and exposure to oxygen can turn it rust-coloured.
While authorities have reassured residents that the discolouration is not linked to pollution, its unusual appearance has raised concerns—particularly with more children expected to be outside during the summer holidays.