With everything in place and all pipes checked and double checked, I replaced the smart plastic housing which covers the RO and T33 filters and all the electrics, leaving the first three filter chambers ‘dangling’ from the unit. I switched on and watched it start up. The unit beeped, the pump began whirring, and the display went from F for fault to an animated circular pattern indicating that it was producing filtered water. Outside, I could see a steady flow of water from the waste pipe.

After a couple of hours, the pressure vessel was full and the pump stopped. Yes, it takes that long to produce 10 litres of water using the RO system! Which is why you need a storage vessel. Water comes out of the RO membrane and into the vessel which contains a bladder inflated to about 50 kPa when empty of water (there’s a valve on the side of the vessel like on a car tyre). This pressure rises as it fills up.

When you open the drinking water tap, water flows back through the same pipe and then through the T33 filter. This final filter is positioned after the storage vessel because of the fact that you are storing de-chlorinated water in the tank, which can impart a taste.

I emptied and refilled the vessel five times (which took many hours). Even after that process, I was advised to discard the first ½ litre of water each time, until some 180 litres had passed through.

The actual unit was excellent value from Vyair (UK) Ltd (with superb customer service too), but we are now locked into a regime of filter replacement (some every six months, some at longer intervals). It does all seem a bit wasteful. Particularly as the end result is not wine, but plain unremarkable water.