I learned the same. I was quite disappointed later to find that, while all the sewage here goes through treatment, it does not get directly pumped back into the

I learned the same. I was quite disappointed later to find that, while all the sewage here goes through treatment, it does not get directly pumped back into the water pipes, but instead gets pumped back into the rivers. Although pragmatically speaking that makes more sense, since surface water is surface water, and completely separating these systems avoids any risk of contamination.