kool maudit

it seems like a bug. i mean, the whole map is dark red -- there is nowhere to place a new filter that isn't polluted. i do have a lot of mods and stex files too. the city has little dirty industry.

so my largest city and the centre of my largest metropolitan region has very suddenly -- overnight -- developed a crippling, city-wide water pollution problem that appears unsolvable. i have tried destroying all pumps and relocating my water pumps to an unpolluted, heavily-forested suburb, but no luck. i have tried destroying the entire pipe network, destroying all industry and planting trees where the industry once was, with a compound of ionizers, pumps and treatment plants at the center and then redoing the pipe network, but no luck. the pollution map is 100% red and the river is black. is this a known issue? what can i do?