Has anyone had experience of dealing with Thames Water in the following circumstances. I am looking at buying a house, but I want to do a kitchen extension, and 'fill in the gap' between the original kitchen and the side wall as the kitchen is tiny. Its at the end of a terrace and the survey says that there is a main drain running along the back and down the side of the property. Would Thames Water negotiate with me before I bought the property? Has anyone had experience of them being helpful or flexible?