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Comment by mcv | Hacker News Reader

It's not ridiculous at all. Salt sea water is not scarce, but clean fresh water is absolutely scarce in many places on Earth. There's a very good reason why many homes moved towards those 'low flow' showers 30 years ago: wasting less water. As the article points out, wasting less water automatically means wasting less energy (mostly for heating the water, but also cleaning and pumping it).

Unfortunately the savings from those more efficient showers from 30 years ago have been undone by those fancy rain showers that everybody wants nowadays.

Fortunately there are also rain showers that recycle the unused water; most shower water goes down the drain completely unused and quite clean. These shower systems recycle the clean water and as a result use much, much less water per minute[0].

[0] https://www.extremetech.com/extreme/170784-recycling-closed-...

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Shower water is going to go into the sanitary sewer, which, if your municipality is smart, is going to discharge upstream of your water treatment intake. Since the sewer and water system would effectively form a mostly-closed loop, reducing the amount of water you dump into the sewer isn't going to have a meaningful impact on the total water you're withdrawing from the environment--it's the lawn care (depending on the aquifer configurations) and agricultural water usage that removes the water from the system entirely.

Are there many municipalities that are that smart? I'm not so sure most municipalities even have separate sewer systems for toilets vs showers. And if they don't, then this is absolutely going to have an impact.

Though I agree that lawn care and agricultural water use are massive issues.

The water system I worked out had their largest wastewater treatment plant discharge at the head of the reservoir for their (admittedly smaller) water treatment plant. If your primary water source is a large nearby lake, there's a decent chance that your wastewater treatment has its output pipe poking at that lake. And if it's a river, even if your output is downstream of your input, chances are that you have a downstream neighbor who is going to be drinking your treated wastewater.

That's not quite a closed system, though. And I'd expect cleaning the water gets harder the more sewage is in it. Besides, a lot of places get their water from underground, which isn't always so easily replenished.

The ridiculous showers are in part a reaction to the limitations of low-flow shower heads. You can get around the limit of 2.5 GPM per head by having multiple heads that add to more than 2.5 GPM.

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