Fears are growing for Monmouth’s water supply, after it was found that Welsh Water is under a second notice from the Drinking Water Inspectorate (DWI).  

The Welsh Water Drinking Treatment works (Mayhill) Hadnock Road, the one under two notices from the DWI.
The Welsh Water Drinking Treatment works (Mayhill) Hadnock Road is under two notices from the DWI. Des Pugh

The notice, dated April 2024, says Welsh Water is to “complete the construction and commissioning of the ultraviolet disinfection systems at Monmouth (Mayhill) Water Treatment Works by March 31, 2028.”The notice says that there is a “Risk of cryptosporidium breakthrough through existing treatment processes into final water.” and that there is “Potential for elevated levels of Cryptosporidium due to its presence in the raw water.”

What is cryptosporidium?

Cryptosporidium is a microscopic parasite that can cause an unpleasant – and sometimes dangerous – illness called cryptosporidiosis. This nasty bug lives in the intestines of infected humans and animals and is passed out in their poo. It can then spread and contaminate water sources like lakes, rivers, and swimming pools, as well as food like raw milk and vegetables.

The symptoms are deeply unpleasant - severe waterydiarrhoea, vomiting, stomach cramps, nausea, fever, and loss of appetite. It can last around 2 weeks, with the illness seeming to improve and then returning before you properly recover. The only way to know for sure if you have the illness is by getting tested by your doctor.


Cryptosporidium is a waterborne organism that causes an infection called cryptosporidiosis affecting people and farm animals. 

However, Welsh Water maintain: “There are no current issues with the drinking water in the Monmouthshire area.

A spokesman said: “The AMP8 UV Disinfection Schemes notice is a result of a document that has been agreed with the Drinking Water Inspectorate (DWI) following the standard process of risk assessment undertaken by Dŵr Cymru Welsh Water.

“This established regulatory process requires us to manage potential future risks and agree a course of action to mitigate them.

“The notice document is the outcome of that process which formally sets out the set of actions that we submitted to DWI and agreed to undertake.

“As the notice name indicates, these actions are planned for our next investment period (AMP8 2025 to 2030) and will lead to us further investing to upgrade our water treatment services in the Monmouthshire area to ensure these potential future risks are managed.”

Residents however, fear the pathogen is chlorine resistant and may not be dealt with by the normal water filtration process at the Monmouth (Mayhill) Water Treatment Works.

While there is no imminent threat to Monmouth’s Drinking Water, the situation will in the future be made worse by proposed housing developments such as 270 houses on Dixton Road and a proposed 110 at Wonastow.

Local Senedd Member Laura Anne Jones has expressed strong criticism of the Labour Senedd Environment Minister for failing to take action on the ongoing issue, of sewage being pumped into the River Wye and River Usk. Despite promises before the election from Labour candidates that they would tackle the crisis. Laura claims that the Governments in Wales and Westminster have gone quiet on the matter, leaving residents and local ecosystems at risk