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RO System Maintenance: When to Change Filters and Membranes
Quick answer: Change sediment and carbon pre-filters every 3–6 months (sooner with dirty borehole water), and replace the RO membrane every 1–3 years or when the product-water TDS rises and output drops even with new pre-filters. Check TDS weekly so you catch problems early.
Key facts
- Pre-filters: every 3–6 months, or when pressure drops
- Membrane: every 1–3 years, or when TDS rises and flow falls
- Weekly: check product TDS and flow; write them down
- Softening or antiscalant protects membranes from scale
On this page
A simple maintenance schedule
| Part | When | Why |
|---|---|---|
| Sediment filter | Every 3–6 months | Traps sand and rust that would block the membrane |
| Carbon filter | Every 3–6 months | Removes chlorine that damages RO membranes |
| RO membrane | Every 1–3 years | Wears and scales, letting TDS rise |
| UV lamp | About every 12 months | UV output falls over time |
| TDS and flow check | Weekly | Early warning of problems |
Signs your membrane needs attention
- Product-water TDS has risen steadily for weeks.
- Output (litres per hour) has dropped even after new pre-filters.
- The pump runs longer to fill the same tank.
Sometimes a membrane only needs cleaning; if TDS stays high after cleaning, replace it.
Filter, housing and membrane prices
Polypropylene Sediment Filter Cartridges 10″ Big BlueKSh 350
Polypropylene Sediment Filter Cartridges 20″ SlimlineKSh 700
Taste & Odour Removal CartridgeKSh 1,200
Carbon Block Coconut Shell Big Blue Cartridges (1um)KSh 1,300
Standard/Slimline Clear Plastic Filter HousingsKSh 1,600
Standard/Slimline Blue Plastic Filter Housings 10″KSh 1,900Current listed prices incl. VAT (updated 30 September 2026). Full range: Water treatment components.
Protect the membrane
- Hard water scales membranes: fit a water softener or dose antiscalant.
- Iron-rich borehole water needs an iron filter first (see borehole water treatment).
- Never run the RO pump dry.
Frequently asked questions
How often should I change RO filters?
Pre-filters every 3–6 months, sooner for dirty borehole water; the membrane every 1–3 years depending on water quality.
How do I know my RO membrane is bad?
Product-water TDS rises and output falls even after new pre-filters.
Can an RO membrane be cleaned?
Yes, scaled or fouled membranes can often be chemically cleaned; replace it if TDS stays high afterwards.
Do you supply replacement membranes and filters?
Yes. See the price table, or ask us to match your existing housing sizes.