Owning your own home

As I understand it, you need a specific survey to map pipes. Our next door neighbor is selling up and their enormous garden has attracted the interest of lots of small scale developers. One paid to have a survey done to map the sewers and culvert that run through the garden.

This is a pain... we found it out when we were building an extension and trying to find out where pipes were. First thing we found out is that there are plans as to where pipes should be, but strong emphasis on should!
In the end we paid for a company to come out and use CCTV to map them. Cost me something like £500 to find one small drainage pipe.

Do surveys ever pick up pipes and stuff that may run under a house?

Our conveyancer got plans from Thames Water showing all the pipework they were aware of. Was accurate.