A couple of useful tips have popped up to help with water pollution. As you know, the coast can become quite polluted as you expand out and open up more zones along the coast. These may be affected by water pollution from pumps further upstream if you’ve not planned carefully.
Here’s a couple of very useful tips that can help combat this problem, one while creating a new map and another which uses a water pumping station to remove the waste from the water with some pipe placement trickery.
ProperFellow suggests placing a pumping station in the middle of the sewage problem and then running a water pipe a short distance onto land. The sewage is then pumped down the pipe and into the ground cleaning up the mess. He also suggests placing one either side of the sewage pump at the start of a game to prevent the sewage from spreading.
The second tip comes from lattekoolaid which is useful if you are creating a new map from scratch and it involves tweaking the height of a water source so that the sewage flows under the map into the “void”. You can see how this has been achieved below.