As many as 40,000 homes could be without water after a burst pipe at a treatment plant.

The incident at Bryn Cowlyd Water Treatment Works in Dolgarrog, Conwy, has closed five schools and impacted businesses and services, including a GP surgery that has cancelled face-to-face appointments.

Welsh Water said about 8,000 homes lost supplies on Wednesday night and another 33,000 were at risk of losing theirs until repairs were complete.

The firm previously said it was affecting Conwy county only, after previously saying properties in Denbighshire were also impacted.

Llanrwst and Conwy library shut on Thursday due to lack of water supply, although some small businesses said they would remain open despite the disruption.

Worthy Hairdressing salon in Conwy has chosen to open its doors under a “dry cuts only” policy and cafe owner Isaac Simeon said he was unable to make hot drinks but had plenty of cakes and sandwiches as normal.

Mr Simeon said: “I can’t make coffee and tea today, but it’s OK, I am open. If not, and there’s no people coming, no problem.”

Tourist attractions Conwy Castle and the National Trust’s Bodnant Gardens will remain closed on Thursday due to the water issue.

Bodreinallt surgery in Conwy has cancelled face-to-face appointments.

Conwy-based breakfast restaurant M&J bistro announced its closure on a Facebook post, adding it would keep customers updated as to whether it can reopen on Friday.

Welsh Water said tankers were being mobilised to keep as many people on supply as possible.

The company added its crews were working on repairs, but the work was “difficult and dangerous” because the burst water main was two-and-a-half metres underneath the river bed.

Crews would have to create a dam-like structure in the river to be able to excavate and access the damaged water main, the company added.

The incident is affecting supplies in Conwy, Dolgarrog, Eglwys Bach, Groesffordd, Gwytherin, Henryd, Llanbedr y Cennin, Llanddoged, Llanfair Talhaiarn, Llangernyw, Maenan, parts of Llanrwst, Pandy Tudur, Pentrefelin, Rowen, Rhyd y foel, Tal y Bont, Tal y Cafn, Tyn Groes and Trofarth.

Councillor Goronwy Edwards, who is responsible for infrastructure and facilities in Conwy, told BBC Radio Wales Breakfast he was waiting for more information but work was under way to set up distribution centres for the vulnerable in Eirias Park, Colwyn Bay.

Welsh Water said customers had been contacted directly by text message to inform them about the issues and bottled water was being delivered to vulnerable customers.