Quick Answer: Filter Replacement Schedule
These are general guidelines. Your actual schedule depends on water quality, usage, and household size. Read on for the details.
Why Filter Replacement Matters
I've been in the water filtration industry for 24 years, and the most common mistake I see is people forgetting to change their filters. It's understandable - out of sight, out of mind. But an overused filter isn't just ineffective; it can actually make your water worse than unfiltered tap water.
What Happens When You Don't Change Your Filter
- •Reduced effectiveness: Activated carbon becomes saturated and stops absorbing contaminants
- •Bacterial growth: Trapped organic matter becomes a breeding ground for bacteria
- •Contaminant release: Overloaded filters can release trapped contaminants back into your water
- •Reduced flow: Clogged filters slow water flow significantly
- •Bad taste returns: Chlorine taste and odour come back
Complete Filter Replacement Schedule
Here's a comprehensive breakdown of replacement schedules for every common filter type in UK homes:
| Filter Type | Frequency | Capacity | Yearly Cost |
|---|---|---|---|
Jug Filter (BRITA, Waterdrop) Hard water areas may need 2-3 week changes | Every 4 weeks | 100 litres | £48-96 |
Faucet Filter (TAPP, Waterdrop) Some models have filter life indicators | Every 3 months | 1,200-1,500 litres | £60-100 |
Under-Sink Carbon (Waterdrop 10UA) Best value for families | Every 6-12 months | 8,000-12,000 litres | £25-80 |
Under-Sink RO Pre-filters Sediment and carbon pre-filters | Every 6-12 months | Varies by usage | £30-60 |
RO Membrane Longest-lasting component | Every 2-3 years | N/A | £15-40 |
Whole House Sediment Depends on water quality | Every 3-6 months | Varies | £40-80 |
Factors That Affect Your Replacement Schedule
Water Hardness
Hard water areas (London, South East, East Anglia) cause faster filter degradation. Limescale builds up on filter media, reducing capacity. You may need to change filters 25-50% more frequently.
Check your water hardness →Household Size
A family of 4 uses roughly 4x the filtered water of a single person. If the manufacturer says "100 litres", a family might hit that in 2 weeks while a single person takes 6 weeks.
Water Temperature
Warmer water (summer months) can accelerate bacterial growth in filters. Some manufacturers recommend more frequent changes during hot weather, especially for jug filters left at room temperature.
Usage Patterns
If you only use filtered water for drinking, your filter lasts longer than if you use it for cooking, coffee, and filling the kettle. Track your actual usage rather than just counting days.
5 Signs Your Filter Needs Changing Now
Don't just rely on the calendar. Here are the warning signs that your filter has reached the end of its life:
1. Reduced Water Flow
If your filtered water is coming out slower than usual, the filter is likely clogged with trapped sediment and contaminants. This is the most obvious sign.
2. Chlorine Taste or Smell Returns
If you start noticing that familiar swimming pool taste again, the activated carbon is saturated and can no longer absorb chlorine.
3. Water Tastes "Off"
A metallic, musty, or generally unpleasant taste can indicate bacterial growth or contaminant release from an overused filter.
4. Visible Discolouration
If you can see your filter (jug filters, some faucet filters), check for brown, green, or black discolouration. This indicates heavy contamination or mould growth.
5. Filter Indicator Light/App Alert
Many modern filters have built-in indicators. Don't ignore them - they're usually based on actual water flow through the filter, not just time.
Pro Tips for Filter Maintenance
- Set a calendar reminder: Don't rely on memory. Set recurring reminders for filter changes.
- Buy in bulk: Replacement filters are often cheaper in multi-packs. Stock up and you'll never be caught without a spare.
- Write the date on the filter: Use a permanent marker to write the installation date directly on the filter housing.
- Subscribe and save: Many brands offer subscription services that deliver filters automatically. Worth considering for convenience.
- Check for genuine parts: Counterfeit filters are a real problem. Buy from authorised retailers or directly from the manufacturer.
Frequently Asked Questions
How often should I change my BRITA filter?
BRITA recommends changing their MAXTRA+ filters every 4 weeks or after filtering 100 litres of water, whichever comes first. However, in hard water areas like London, you may need to change them more frequently - every 2-3 weeks - as limescale builds up faster.
What happens if I don't change my water filter?
An overused filter becomes less effective at removing contaminants, may develop bacterial growth, and can actually release trapped contaminants back into your water. You may notice reduced water flow, bad taste, or odour - all signs the filter needs replacing.
How do I know when my water filter needs changing?
Signs include: reduced water flow rate, return of chlorine taste or smell, visible discolouration of the filter, water tasting 'off', and exceeding the manufacturer's recommended timeframe or litre capacity. Many modern filters have indicator lights or apps to track usage.
Do water filters expire if not used?
Unopened water filter cartridges typically have a shelf life of 2-3 years. Once opened and installed, the replacement schedule begins regardless of how much water you filter. Activated carbon can degrade over time even without use.
About Keith
Trained engineer (toolmaker) with 25 years in industrial coatings filtration, plus 18 years refining RO/carbon/resin purified-water systems
On Filter Authority, Keith translates hands-on experience into plain-English guidance and evidence-led, certification-aware recommendations for UK homes. You won't find hype here — just clear options, honest trade-offs, and how to check claims for yourself.
Read full bio and methodology