How Does an RO Water Purifier Work? A Simple Guide

What Reverse Osmosis Actually Does

Reverse Osmosis (RO) uses pressure to push water through a super-fine membrane that blocks dissolved salts, heavy metals, pesticides and other impurities. The membrane holes are 0.0001 microns — small enough to stop contaminants while letting water molecules through.

This is why RO is essential where TDS (Total Dissolved Solids) is high. In cities like Raipur with hard, high-TDS borewell and municipal water, only an RO stage reliably brings TDS down to safe drinking levels.

The 5 Stages in Every Good RO

A standard domestic RO purifier passes water through five stages. Each one has a specific job:

• Stage 1 — Sediment filter: removes sand, rust and visible particles that would clog the system
• Stage 2 — Pre-carbon filter: removes chlorine and organic compounds that would damage the membrane
• Stage 3 — RO membrane: the heart of the system, removes dissolved salts, heavy metals and 90-95% of TDS
• Stage 4 — Post-carbon / UV stage: polishes taste and kills bacteria and viruses
• Stage 5 — Mineral/alkaline cartridge: restores beneficial minerals and balances pH for better-tasting water

Why UV and UF Are Added (RO + UV + UF)

RO removes chemicals and salts but does not guarantee 100% disinfection in every situation. Adding UV (ultraviolet light) kills bacteria and viruses, while UF (ultrafiltration) blocks larger microbes as a final safety net.

For households on municipal supply, a 5-stage RO+UF is usually enough. For those mixing borewell or tanker water, an RO+UV+UF system like the AQUAOCEAN Pro gives complete protection.

What Happens to the Rejected Water

RO systems reject a portion of water carrying the concentrated impurities. Modern machines like ours keep rejection low at 1:1 to 1:1.5 — you get one litre of pure water for every one to one-and-a-half litres used. This reject water can be reused for mopping, gardening or washing.

How to Know Your RO Is Working

Test the TDS of your purified water annually (a simple TDS meter costs ₹200-₹500). If output TDS rises above 50-100, or your water tastes flat, the membrane or filters need attention. Our free service check includes TDS testing and filter inspection.