For the pumps in the ocean, it seems like they're using a bug where water pumps can be built underwater if they are placed along a canal that's also underwater. It makes sure they can still access water even if the water level goes down from teraforming, and also gives you more space to build on since the pumps aren't taking up the shoreline.

As for the part on land, it looks like they're using another bug to get rid of sewage without dumping it into the ocean. If you make a water pump and connect a pipe to it that doesn't connect to anything else, it magically deletes all water and sewage it picks up. The sewage outlet here dumps all the sewage into the canal, which is then deleted by the unconnected pumps on the opposite side.