The storage tank of an RO or UV water purifier can develop a slimy film, smell, or visible deposits over time. Cleaning it periodically keeps your drinking water fresh and safe. This guide gives a quick answer first, then a full step-by-step method.
Quick answer
To clean a water purifier tank at home, switch off and unplug the unit, empty the tank, detach it if possible, scrub the inside with a soft brush and a mild food-safe cleaning solution (diluted vinegar or a little baking soda), rinse thoroughly several times, and refill. Do this every 3–6 months, or sooner if you notice odour or film.
Signs your tank needs cleaning
- Musty or stale smell from dispensed water.
- Slimy film on the inner tank walls.
- Visible sediment or discoloration.
- Off taste even though filters are not overdue.
Step-by-step cleaning
- Switch off and unplug: Disconnect power and close the input water valve.
- Empty the tank: Dispense all stored water through the tap.
- Detach the tank if possible: On some models the tank lifts out; otherwise clean in place.
- Prepare a mild solution: Use diluted white vinegar or a teaspoon of baking soda in water. Avoid harsh chemicals or bleach near drinking water surfaces.
- Scrub gently: Use a soft brush or clean cloth on the inner walls and corners.
- Rinse thoroughly: Rinse at least 3–4 times with clean water until no smell of cleaner remains.
- Reassemble and flush: Refit the tank, restore power and water, let it fill, then discard the first full tank before drinking.
A soft cleaning brush set makes this much easier.
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How often to clean
Clean the tank every 3–6 months under normal use, or more often in humid climates or if the purifier sits idle for long periods. Tank cleaning complements, but does not replace, filter changes — see our guide on how often to change the RO membrane.
Prevention
- Do not let purified water sit unused for days; drain and refresh.
- Keep the unit out of direct sunlight to discourage growth.
- On UV models, ensure the UV lamp is working — it helps keep stored water safe.
- Service the unit on schedule.
When to call a technician
Call service if the smell or film returns quickly after cleaning, if the tank is cracked or leaking, or if you suspect the UV lamp has failed. Persistent contamination may need professional sanitisation. If taste problems continue, verify purification is working by checking output — see our guide on how to check RO TDS output at home. To understand what each technology removes, see our RO vs UV vs UF guide.
Frequently asked questions
Can I use bleach to clean the tank?
Avoid bleach near drinking water surfaces. Use diluted vinegar or baking soda and rinse thoroughly.
How often should I clean the tank?
Every 3–6 months, or sooner if you notice smell, film or off taste.
Why does my purifier water smell musty?
Usually biofilm in the tank; cleaning and discarding the first refill normally fixes it.
Do I need to remove the tank?
Not always — many tanks can be cleaned in place if they do not detach.
Should I discard water after cleaning?
Yes, drain the first full tank after cleaning to remove any cleaner residue.