The Independent Monitoring Board says the jail is suffering with an unreliable heating and hot water supply.
An incident last November saw a “loss of service” affecting the heating and as a result, temperatures can fall as low as 12C.
An additional 1,500 coats, 1,000 blankets and 2,000 packages of instant food were ordered for inmates during the initial outage.
But the IMB says the heating system needs to be replaced at the Victorian Category B men’s prison.
A Ministry of Justice spokesperson said:
“While this report recognises progress at HMP Wandsworth we know there is more to do.
“Former Home Secretary Amber Rudd is leading an independent review to deliver safer prisons, keep the public safe, and cut reoffending
