I have worked in the industry for about six years, currently I’m a data analyst. There are several issues with the technology your wanting. The first is the condition of existing waste water lines. Even if you can get signals to transmit through a variety of pipe construction, at depths between 2ft- 10ft+ , most sanitary laterals can be approaching 100 years of service. They can have tree roots, offset joints, calcium deposits, this will effect how well a transmitter will travel through the lateral. In the field we sometimes flushed a wireless sonde attached to fishing line to transmit radio signal to a locator used above ground, however this was seldom used due to the difficulty in getting it to travel the full length of the line, and the inaccuracies of the depths. After the lateral empties into the sanitary mainline, there are also a variety of issues with condition of pipe, same as stated above but with a lot more debris buildup. Most municipalities don’t have the resources to clean sanitary Mainline’s unless there is an absolute need to do so. Some have excellent mapping, but most have insufficient information. Best way to get sewer lateral information is to hire a plumber who uses push camera technology to get location and depth of the lateral, after that good luck with the city’s sanitary main. I have inspected thousands of sanitary laterals, operating sewer camera trucks via manholes, as well as push camera equipment and worked on multiple utility projects in several states. If I can answer any further questions, I would be happy to.