it turned out that the 4 houses that share the back garden were all affected, and the fault was the responsibility of the water board, UNTIL they realised that in the past all 4 houses had been owned by the same person, which by some ancient law meant that we 4 were responsible. i contacted citizen's advice and they told me the same, so we split it 4 ways.
has anyone got any mattresses / mats / crash pads? i can collect from anywhere in sheffield.