Start with the problem you're solving.
It's sensible to ask what you want a filter to improve. If you dislike the taste or odour of otherwise compliant mains water, you may not need the expense and complexity of reverse osmosis. A suitable activated-carbon filter can help with certain taste and odour issues, depending on its certified capabilities.
Activated carbon filters
Often fitted as jugs, taps or under-sink cartridges, these are generally simpler than RO systems. Their performance is contaminant- and cartridge-specific: do not assume every carbon filter treats every substance.
Reverse osmosis systems
RO systems force water through a membrane and discharge a separate stream of water. This can address a different set of water-quality preferences, but involves more complexity, filter changes and running costs. Whether an RO system is suitable depends on the actual water and the device's verified performance data.
Which approach makes sense?
| Use case | Start here |
|---|---|
| Prefer the taste or odour of filtered water | Consider appropriate carbon filtration first |
| Want a dedicated RO membrane-based system | Compare RO certifications and replacement costs |
| Cloudy water, sudden discolouration or official supply notice | Contact water provider; do not self-prescribe a filter |
| No meaningful water issue | Consider not buying a filter |
Ask for evidence
Check certified contaminant-reduction claims, replacement frequency and model-specific performance data, not vague statements about “pure” or “alkaline” water. A certification number alone is not proof that every possible contaminant is covered.
Sources & verification
Facts below are taken from the linked sources; product information may change. Last editorial check: 13 November 2026. No hands-on product testing was performed.