Police are investigating vandalism at Caernarfon wastewater treatment site that has caused £250,000 worth of damage.

Security guards say they have seen youths at the site, and have CCTV footage of them breaking in.

The site provides essential services for Welsh Water customers, cleaning and treating sewage wastewater for over 12,000 homes and businesses.

Police have been called to site over recent months following break-ins and damage to water treatment equipment by the youths. Windows and doors have been shattered, specialist machinery has been tampered with and thrown into water tanks. Damage has also been done to perimeter fencing.

North Wales Fire Service has attended the site following acts of arson when trees were set on fire.

Additional security measures have been put in place including CCTV and a full-time security guard. The security guard has been attacked by the group who have thrown stones and other objects.

North Wales Police visited the local high school with staff from Welsh Water to highlight the dangers of breaking into the site.

Welsh Water is urging people to report suspicious activity around the site to police to prevent further damage and ensure the safety of everyone involved.

Victoria Collier, Catchment Manager for Welsh Water, said: “These break-ins are very concerning for us. Welsh Water is the only not-for-profit water company in England and Wales, therefore customers’ bills shouldn’t be used to pay for damage, but for investments and upgrades.

“Beyond the financial implications and environmental harm, our biggest concerns are for the health and safety of those involved. There is a reason why the site has security fencing and warning signs. The site contains very deep, aerated tanks, which means that should anything or anyone fall in, they would be pulled to the bottom and unable to float.”

The company recently had to empty several tanks to retrieve equipment thrown into them. Contractors have also had to cut down trees that were set alight causing substantial damage to the site.

Victoria added: “Those who have broken in have also tampered with equipment which disrupted the site’s operations and could have caused significant environmental damage. We are working closely with the police to identify those involved and to highlight the dangers of entering sites like these.”

Chief Inspector Stephen Pawson: “We are concerned that these individuals are risking serious injury or worse every time they trespass onto the site.

“In particular, we are urging parents and carers to check where their children are during the evenings and make it clear to them about the risks involved.

“We are working closely with Welsh Water to deter these youngsters from accessing the site. The local policing team are carrying out high-visibility patrols around the site and are also liaising with local schools in the area.

“It is important that those involved understand they are committing offences by behaving in this way, and those who are involved will be dealt with robustly. Anybody who witnesses anti-social behaviour around the site is urged to contact North Wales Police immediately.”