A whole-house water filter must handle the property’s peak flow while delivering the specific verified treatment claim. Select media and stages from the water analysis and objective, then check pressure loss, drain and power needs, installation access, cartridge or media life and verification testing.
The seven-step selection method
- Identify the water source and obtain representative test data.
- Write the treatment objective in measurable terms.
- Measure static/dynamic pressure and estimate peak flow.
- Select technology with certification or performance evidence for the exact claim.
- Calculate pressure drop and service flow in the final configuration.
- Plan bypass, isolation, drain, power, leak protection and maintenance access.
- Budget replacement media, consumables, testing and service over several years.
Common technologies and limitations
| Technology | Often used for | Do not assume |
|---|---|---|
| Sediment filtration | Particles above a rated size | That it removes dissolved chemicals or hardness |
| Activated carbon | Specified chlorine, taste, odour or organic-compound claims | That all carbon products have the same capacity or certification |
| Softening / ion exchange | Hardness reduction | That softened water equals broad contaminant removal |
| Reverse osmosis | Specified point-of-use dissolved-contaminant reduction | That it is always the correct whole-house solution |
| UV | Microbiological treatment under defined feed-water conditions | That UV removes sediment or chemicals |
How to read certification
Look for the certifier, standard, exact model and exact contaminant-reduction claim. NSF notes that the number is not a ranking and that a certified filter does not automatically reduce every contaminant. Review the NSF standards summary before comparing proposals.
Maintenance is part of system sizing
A neglected filter can create pressure loss, bypass risk or poor performance. Record differential pressure, replacement intervals, media volume, sanitation procedure and spare-stock responsibility. Where the system makes a health-related reduction claim, include periodic verification appropriate to the risk and local requirements.
Next step
Return to the water filtration systems hub and send the feed-water data, treatment objective, flow and installation photos for a scoped response.