This idea comes for free if you're also using hot water in radiators as a way to heat your home at the same time. Which the Soviets did. And in the Soviet era, they also were generally heating that water at the district level, then circulating it to all of the homes. This can only be workable if you're pumping the water continuously. So the cost of the pumping is just part of the overall system.
Places where this was built up, still generally use it today.
In the USA, nobody ever built the district wide heaters. Nor would they be viable in the suburbs that many of us live in. We generally use central air instead of radiators to heat our houses. And the result is that constantly circulating hot water is significantly more expensive for us.
the places i lived in germany and china did have district wide heaters, but only for the water that circulated the heaters, not the water that came out of the tap. i believe the reason being that tap water needs to be potable (at least in germany, in china you still need to at least boil the tap water), whereas water for heating doesn't. you don't actually want your tap water go through the heating system. fun story: in china i once managed to open the heating pipe. the water that came out of that was black. probably rust and other stuff from the pipes. i wonder how the soviets managed to keep the water clean.
They did it this way: from the powerplant, it was hot steam under pressure, not even water, that got to the block-sized heat exchanger (serving maybe 500-1000 people, 200-300 flats - one large soviet-style block or 2-3 smaller ones). There, heat exchanger warmed the technical (indeed totally non-potable, almost poisonous, and constantly circulating) water for the heaters, that was only there during the heating season, and separately, tap water, these were two completely different, non-mixing circuits (and both of them short without much insulation - maybe around 100 meters each way outside, plus within the buildings). And sure the tap water wasn't potable, but it had nothing to do with the way it was heated - there were two completely different circuits for hot and cold water anyway, cold water never entered the heat exchanger building. It was always a separate building by the way, i think because a potential accident with high pressure steam could kill a lot of people if it happened right within the residential building itself.
We were told that hot tap water was totally dangerous to drink and no one tried to. Cold water was unsafe to drink but some people either had reverse osmosis filters, which i know aren't good because they deprive water of a lot of useful stuff too, but no one knew it back then, or they boiled it, but most just drank it as it was. Shorter lifespans and much lower average age, and plenty of other life dangers like mass alcoholism, made water quality was a lot less important than it is today in the West - it won't be water that kills you anyway, it's vodka, lifestyle, of the Party itself.
Places where this was built up, still generally use it today.
In the USA, nobody ever built the district wide heaters. Nor would they be viable in the suburbs that many of us live in. We generally use central air instead of radiators to heat our houses. And the result is that constantly circulating hot water is significantly more expensive for us.
Does that answer your question?