"Sorry, we might go bust next year," is not what you want to hear from your water company. Ideally we wouldn't have water companies at all, we'd have one competent publicly owned authority, but we are where we are and this is the shitshow we've ended up with. So I wondered, how much of London does Thames Water cover and how close am I to not being one of their customers? Good maps aren't easy to find.
Thames Water offer a schematic map which shows their domain comes in three blue chunks - one from the Cotswolds down to Slough, one around Guildford and another covering much of London. But not all of London. Affinity Water curves round the west and north, Sutton & East Surrey Water comes in from the south and other companies nibble from the east. Meanwhile the grey areas show where Thames Water deals with sewage - i.e. someone else delivers the water but they take it away. The grey is so widespread it looks like Thames Water might deal with all of London's wastewater, as befits a capital city straddling the Thames estuary, but the map's not good enough to be certain.
In an attempt to find the dividing line between Thames Water and Not Thames Water I Googled a lot but failed to find a zoomable map. I did find an official website where you type in your postcode and it tells you your supplier, but that's no way to explore a large capital city. I also called up the London Infrastructure Map and selected the Water layers, but although they're very precise they don't say who's supplying who. What I did eventually find is one decent map of Water Company Areas tucked away inside London Resilience Partnership Water Supply Disruption Plan Version 2.0 (December 2017), and here it is. If anyone'd need to know in a hurry it'd be them.
So...
» Everyone in inner London gets their water from Thames Water. Haringey, Waltham Forest, Newham, Greenwich, Bexley and Richmond are 100% in the TW club too.
» Affinity Water supply all of Harrow and Hillingdon, most of Barnet, half of Brent and Ealing, part of Hounslow and not much of Enfield.
» Sutton & East Surrey Water feed almost all of Sutton, unsurprisingly, plus half of Croydon and slivers of Merton, Bromley and Kingston.
» Essex and Suffolk Water cover all of Havering and Barking & Dagenham and most of Redbridge.
It turns out that I live nowhere near the Thames Water boundary, which appears to approximately follow the River Roding. The western edge, meanwhile, looks like it follows the River Brent a lot of the way, while the southern boundary is less well defined. Further research suggests that Sutton & East Surrey Water is the cheapest of the four, bills-wise, and Essex and Suffolk Water the most expensive.
The map also reveals that one small corner of east London disposes of its wastewater via another company - Anglian Water. That area is the eastern tip of London between Upminster and North Ockendon where they get their water from Essex and Suffolk but flush it away to Anglian. The boundary's not quite as simple as it looks on the map, as use of a postcode checker confirms, but there are definitely streets in Cranham which escape Thames Water altogether. Lucky them.
