Don't see anything terrible there. You are talking out your ass.
The mass of helium is 4.002602 g/mol. Divide by Avogdro's number, and a single atom of helium weighs 6.646E-24 g. The difference in mass is what powers the sun. Parent is simply making the same argument on the scale of a proton split into its parts.
(disclaimer: I know, blabla deuterium, not protons and neutrons. However, see the definition of a state function.)
At our plant, we have a water reclamation facility at the end of our process, the same type of facility used at the water treatment plant upstream. A WRF is common, iirc, in CA, but is, afaik, the first of its kind here in MN. It is far more common to discharge without the additional filtering and contaminant removal provided by a WRF.
The water we discharge is tested biweekly for ammonia and phosphorus and daily for total coliforms and biological oxygen demand. Ammonia and coliforms are non-detectable ~99% of the time. We are doing a very good job turning sewage into drinking water for the next town on the river.