The cost of water usually appears on your bill. But it’s not the whole story. You’re also paying, directly and indirectly, for continuing repairs to outdated infrastructure. For investment in future infrastructure. For emergency work when a main bursts. And for the detours, traffic jams, parking restrictions and delays that come with any repairs and improvements.

Its considerations like these that allow us to claim that a mass-market Aqua21 system is something to aspire to. It doesn’t block traffic or require a vast Victorian infrastructure. It’s also possible to use it with locally supplied untreated water as it doesn’t rely on water cleaned in bulk before delivery; it cleans it at the point of use.

Of course it isn’t – yet – able to treat water for entire cities. In any case mass-market affordability means components that can be made reliably and cheaply and be deployed easily – and we’re not there yet.

The actual ozonation machinery is less of a cost issue than the sensors that tell users the water is safe. We learned long ago that if you’re going to deploy sensors in the field, they’ve got to be very cheap, very nimble and very simple. Not to mention reliable, small, reproducible and easily manufactured, especially in the developing world.

We learned that lesson the hard way. During one of the development phases of our technology, we knew what we were aiming for – and we designed it, putting together control boards and generators that worked but that were expensive and unwieldy.

We looked at that, learned from it and decided we needed to start again: to develop our own sensor. You can see the result today: it has no moving parts, is electronic and lasts for a very long time. It’s also power efficient and takes up about as much space as an iPhone. It took the best part of a year, but it changed everything.

Costs are coming down too. We can now reproduce a sensor and deploy it in the field for about $100 (something like a tenth of the cost we started with). The price of components is still relatively high but when we start to produce sensors in larger quantities the economies of scale will vastly diminish that cost.

So now we have an ozone generator that is highly efficient, small and costs very little. And we have a lightweight dissolved ozone sensor whose production cost is falling. That equipment can produce ozonated water that it is measured and assured safe at point of use. And, over time, it will be more cost-effective in many situations than using, or repairing, existing water supply infrastructure.

All this has happened only a few years since we saw an ozonation machine and thought: “This is a crude, inefficient machine. They cost tens of thousands of dollars. Surely we can do better.”

And we did.