@TheOrchidKiller
It's unlikely to be even postcode specific. It will most likely be set on what are called 'catchments'. Each catchment will go to a treatment plant. The plants will serve anywhere between 1000 and 30,000 houses, the larger stations will be more accessible so that's the place to start.
Also, the water companies have a very sketchy idea of how many drains they actually have all thanks to the sewer transfer act which gave them responsibility for sewers previously owned by a local authority, mainly constructed under public health act. Which dates back to 1848. You can imagine the record keeping. Not exactly digital format.
The likelyhood of them pinpointing an exact house (or street) is slim to none. Streets can cross drainage catchments and they don't really follow things you can see, they are based on the level and capacity of the infrastructure. Your next door neighbour could drain to a completely different treatment works to you.
If the tech is rolled out to pumping stations (the next easiest place) then the area could be refined, but as pumping stations can serve anything between 2 and 10000 homes it doesn't refine it that much. And you will be putting the tech in the larger ones first.
(Sorry, sewerage is my specialist subject)