04/06/2026
A *7 stage RO system* is a reverse osmosis water purifier with 7 filtration steps. More stages = more thorough cleaning + taste improvement.
This is how the water flows through each stage:
# # # *7 Stage RO System Breakdown*
1. *Stage 1: PP Sediment Filter - 5 micron*
*Job*: Removes physical particles
Catches dust, rust, sand, silt. Protects the next stages from clogging.
2. *Stage 2: Granular Activated Carbon GAC Filter*
*Job*: Removes chlorine, bad odor, organic compounds
Chlorine damages the RO membrane, so this stage protects it + improves taste.
3. *Stage 3: Carbon Block Filter - 1 micron*
*Job*: Fine filtration + chemical removal
Removes finer particles, residual chlorine, pesticides, and VOCs. Gives extra protection to the RO membrane.
4. *Stage 4: RO Membrane - 0.0001 micron*
*Job*: Main purification stage
This is the heart of the system. Water is pushed through a semi-permeable membrane at high pressure. It blocks dissolved salts, heavy metals like lead/arsenic, bacteria, viruses, nitrates, fluoride. ∼95-98% of TDS is removed here. Waste water is drained out.
5. *Stage 5: Post Carbon Filter / In-line Carbon*
*Job*: Taste & odor polishing
After storage tank, water passes through this to remove any tank smell and make taste fresh.
6. *Stage 6: Mineral Filter / Alkaline Cartridge*
*Job*: Add back good minerals
RO removes minerals too. This stage adds back calcium, magnesium, potassium. It also raises pH slightly to make water alkaline. Better taste + health benefit.
7. *Stage 7: UV / UF / TDS Controller / Bio-alkaline*
*Job*: Final safety + taste boost
Different brands use different tech here:
- *UV Lamp*: Kills bacteria/viruses if power is on, gives extra safety
- *UF Membrane*: Extra physical barrier, works without electricity
- *TDS Controller*: Mixes a bit of raw water to keep TDS in drinking range
- *Bio/Energy cartridge*: Adds minerals/ORP for "energized" water
# # # *Key points*
- *Stages 1-4* = Purification. This is actual RO filtration.
- *Stages 5-7* = Polishing + remineralization + taste.
- *Waste ratio*: Typically 1:3. For 1L pure water, ∼3L goes to drain.
- *Storage tank*: 8-12L tank stores purified water after
