It is a scam but also a need where water supply is bad. U may die thinking it's clear water unless you check it's TDS by that Instrument.
Regarding UV how will we know that they are providing real UV light, who owns a Spectrometer ?
But aftersales service is worst & cheating on every company. Highly over charging customers.
"RO is needed only when TDS is high in water" - what about arsenic? as per my understanding arsenic doesn't increase the tds
I want to know how our past generation solved this problem without these purifier... anyone know here
Ground water has become polluted since green revolution in 1970s. So the kind of water that was available before that is much different from now.
This is true atleast for agricultural areas .
Rest, you can always boil water , that option always exists, not cost effective though. Not effective for heavy metals though. There was no awareness about it a century back.