But in the absence of a Government price tag, the market has put a value on water in some of our driest regions: between 70c and $1.60 for a thousand litres - a cubic metre - and most recently about $1.
That's about a tenth of 1 cent per litre, but the real price is less because buyers pay once for permits giving them annual rights lasting years, or decades.
The money is going to farmers selling surplus water permits they no longer need for tens or hundreds of thousands of dollars (sometimes more).
And the trading is happening in catchments where councils say streams and rivers are already stretched beyond capacity.
And the real kicker is that farmers pay nothing for the water they're selling to each other. A public resource is effectively privatised by allocating resource consents for it and allowing their transfer between parties. And the revenue from that resource is captured privately, rather than benefiting the public.
Its time to end this legalised theft by farmers. Its time to end our primitive "first come, first served" system of water allocation, which has resulted in overallocation, polluted rivers, and legal theft. Instead, we need to reassess allocations to a sustainable level, and make farmers and commercial users pay for the water they use. This will require acknowledging original Maori ownership, and reaching a settlement with iwi over it, but that's not beyond the wit of our government. If they could do it for fish, for aquaculture space, and for the radio spectrum, they can do it for water.