I don't trust the manufacturer, but I can test the manufacturers water.
I don't trust my municipality because they cheaped out on the corrosion inhibitors chemistry, leached lead into the water and my house is now filled with developing pinhole leaks. I've had five in four years.
What system are you using? My five stage filter system has me replace the charcoal filters once a year and the RO every... three? Maybe five?
But let's assume it costs you $150 a year. Thats less than $0.50 a day for drinking and cooking water. I doubt you could buy any significant amount of bottled water for fifty cents.
I've thought about this, but I don't think so. My last two paragraphs addresses what I think are RO's risks.
First there has to be bacteria in the municipal water. The city does a pretty good job there,
Second there has to be organic matter for the bacteria to grow. Again, cities are good with that.
But even if you have bacteria in your water, a good RO system's pores should be smaller than a virus (really smaller than a prion) or it won't be able to remove metallic ions.
But let's assume after two years these assumptions fail because the filters get old. Replace the filters and flush the system with bleach.
My fear with RO are bad filters. I once had a Zero pitcher and it tasted bad, acidic. A few weeks later there was a recall that the RO membrane was leaking ionomers.
Moral of the story- trust your senses. If municipal water tastes bad, it's bad. If bottled water tastes bad, it's bad. If RO water tastes bad, it's bad.
Its extremely unlikely that German water isn't chlorinated. Perhaps you are thinking about fluorinated?
Chlorine in water is actually fine and tasteless at the concentrations it reaches at the taps - it's basically extremely diluted stomach acid.
The problem is chloramines caused by chlorinated organics. These give water the swimming pool smell and are bad for you.
The solution is easy - reduce the organics in the water before chlorination, and oxygenate (aerate) the water before delivery. But systems can get overwhelmed by too much rain and runoff.
So why test?