Buying a house, which has a lean to conservatory. In the lean-to, where the water drains into the gully from the kitchen, there is no access, it has been concreted over and the pipes just appear to go into the ground. Obviously, if there was a blockage, this would be a problem. Any ideas on how to get around the issue and how much it would cost roughly? There is no man hole chamber in the garden that we could see either.