Dear Mr Knowles,
Thank you for your enquiry with Vertar.
Approximately ten litres of purified water should be sufficient to rinse an
average four door saloon car.
These figures are intended as guidelines only. Factors that reduce filter
life include, hard water sources, use from a water softener (due to added
salt content) and water from bore holes.
Given the information above here are the guidelines for your reference.
Hard Water Area
0ppm - 20 washes
30ppm - 25 washes
Medium Water Area
0ppm - 31 washes
30ppm - 48 washes
Soft Water Area
0ppm - 62 washes
30ppm - 70 washes
I hope the above information answers your queries but please do not hesitate
to contact us should you have any further.
I've just re-read the original page and actually that information was at the bottom - d'oh!
I reckon I'm in a medium area so approximately 30-50 washes. That works out at roughly £1 per rinse. The Flash refills are about £4.99 so that works out at about £1.50 per rinse. I suppose it's worth looking at...