Agriculture uses roughly seventy percent of the fresh water worldwide.
Efficiency improvements therefore look like the obvious answer to .
The result in practice is frequently the opposite, for a reason that is now well documented.
A farmer who installs uses less water per hectare.
With the saving, the same farmer plants a larger area or a thirstier crop.
-level consumption rises even though every individual field is more efficient.
Water that used to return to the aquifer as no longer does.
Subsidies for efficient equipment have accelerated this in several countries.
The only measure that reliably reduces use is a on the volume .
A requires measurement, and measurement is where such schemes usually stop.
Meters are expensive, easy to bypass and politically difficult to install on private wells.
Where farmers manage the collectively, has been far higher.
A neighbour who knows the aquifer is shared enforces the rule more effectively than an inspector.
Such arrangements fail when the group is too large to observe itself.
That, rather than any technology, is the real limit on managing a shared resource.