r/askscience • u/chikinwing15 • Mar 05 '19

Planetary Sci. Why do people say “conserve water” when it evaporates and recycles itself?

We see everyone saying “conserve water” and that we shouldn’t “waste” water but didn’t we all learn in middle school about the water cycle and how it reuses water? I’m genuinely curious, I just have never understood it and why it matter that we don’t take long showers or keep a faucet running or whatever. I’ve just always been under the impression water can’t be wasted. Thanks!

Edit: wow everyone, thanks for the responses! I posted it and went to bed, just woke up to see all of the replies. Thanks everyone so much, it’s been really helpful. Keep it coming!

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u/aronnax512 Mar 05 '19

Right, but this neglects the amoritized cost and O&M of the infrastructure. Sure, gravity is free, but dams, 73 miles of concrete pipe and all the people involved in maintaining and inspecting the system have an energy cost associated with them.

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u/Ochib Mar 05 '19

As it has been in operation since the late 1800s. The amortized cost is now almost zero

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u/aronnax512 Mar 05 '19

In this specific case, the cost of O&M goes up because it's over a century old. There'll also be substantial reconstruction/refurbishment in the near future (design life for concrete structures is typically 75-100 years).

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u/[deleted] Mar 05 '19

That repair took place in 2016.

Birmingham has the benefit of that water being essentially subsidised though, as Wales is blocked from profiting from the resource by the devolution settlement (Wales can't make any decision on water that might negatively affect England).

The result of that is water bills around Elan Valley are higher than in Birmingham, despite that same water being pumped 73 miles to the city.