Every purifier is described by what it removes. Almost none are described by what they leave behind, which is odd, because that is the part you actually drink.
IAPMO India tested both machines the same way, at the same feed conditions, and measured the water that came out. That makes the comparison unusually clean.
The headline number
Total dissolved solids is the simplest measure of how much mineral content a water still carries. Across fifteen tested conditions the Biofier’s output ran between 63 and 192 mg/L. The competing RO’s output, across its four, ran between 23 and 50 mg/L.
Matched feed for matched feed — the same water going in — that is close to three times as much left in the glass.
- Feed around 280 mg/L: Biofier out at 92, RO out at 30.
- Feed around 520 mg/L: Biofier out at 112, RO out at 36.
- Feed around 755 mg/L: Biofier out at 136, RO out at 50.
Is more always better?
No, and this is where the standard matters. IS 10500 sets acceptable limits for Indian drinking water: 500 mg/L for TDS, 200 for total hardness, 75 for calcium, 30 for magnesium, and a pH band of 6.5 to 8.5.
Every single Biofier reading across all fifteen conditions sat inside those limits. Hardness came out between 12 and 29 mg/L, calcium between 2 and 7.6, magnesium between 1 and 3.8, pH between 6.75 and 7.21. So the water is neither stripped nor overloaded — it lands in the range drinking water is meant to occupy.
The RO’s permeate pH, for comparison, ran 9.69 to 9.77 across its four runs. That is outside the BIS band in every one of them.
One boundary worth being straight about
The threefold figure is total dissolved minerals. Calcium and magnesium specifically came out at broadly similar levels in both machines at matched feeds — around 3 to 5 mg/L of calcium either way.
What separates them is everything else still in solution: chloride, sulphate, sodium, bicarbonates. The Biofier left 38 to 93 mg/L of chloride and 24 to 58 of sodium where the RO left 2 to 14 and 2 to 12. That is the difference between water with a mineral profile and water with almost nothing in it.
IAPMO India reports IAPMO/ILAB/20800/26-27 (Biofier, five feed TDS levels at three hardness settings each) and IAPMO/ILAB/20667C/25-26 (competitor RO, four conditions). Both commissioned by Crompton, both conducted independently.
If you want the practical version of all this, it is on your tongue and in a jar of moong. Neither needs a report.
