The Salberga prison in Sala is a Class 1 correction facility with a capacity for 248 inmates, which makes it one of Sweden's largest correction facilities. A Class 1 facility is the highest security level facility in Sweden with isolation cells. There are approximately 300 employees at the institution, most of them prison wardens.

Prisoners in isolation are inventive so to be able to communicate between the cells they began to use the sewer system as a communication channel. By siphoning the water from the toilet, they were able to talk to each other through the sewer pipes. When this was discovered by the Wardens measures had to be taken.