Earlier quoted context omitted.
I use a Kärcher SC3 steam cleaner. It's cheap (~€100) and pretty good. Even the SC2 is decent. As an alternative, Polti high-end ones are excellent. They invented domestic steamers, and I've seen some used at hospitals. The have accessories for e.g. steaming your mattress to get rid of dust mites. I use a Miele C3 Silence vacuum cleaner. It's the cheapest (~€220) Miele vacuum cleaner that has top (A class in EU) filt…
Do the steam cleaners work with hard water? Our area has really hard water and I need to use a reverse osmosis filter even for our humidifier otherwise the scaling is really bad and accumulates quickly.
In any case, they use little water. Like 1 tank for 90 m^2. You can always buy distilled water, or use water from your osmosis filter.