Sources & filtration claims

Manufacturer manuals and current product specifications establish model fit, capacity, operating limits and maintenance. We favour the original document over copied retailer descriptions.

Water and installation guidance

We use the relevant water regulator, supplier and UK fitting guidance for the location and task. The Drinking Water Inspectorate consumer guidance cited on this site applies to England and Wales; readers elsewhere should consult their local supplier and regulator.

Independently checkable claims

A certification needs an exact model, named reduction and stated conditions. A test to a standard is not automatically a current product certification. We do not imply that certification applies to every cartridge in a manufacturer's range.

Calculations and comparisons

We combine published inputs into practical calculations and decision tables, with the sources, assumptions and formulas alongside the result. Our cartridge-cost analysis shows how daily use changes replacement intervals and effective costs, with downloadable calculation rows. The cartridge replacement decisions turn published fit rules into next steps, while the fridge-fit analysis combines dimensions with serving capacity and illustrative storage spaces. The dispenser-versus-kettle energy analysis separates ideal water heat, background electricity and hypothetical portion-control costs. The inputs and decisions are downloadable. A calculated result remains conditional on its inputs; it does not establish a separate filtration claim.

Retailer information and images

A retailer listing establishes a purchase option and selected pack, rather than authority for every filtration claim. Amazon product images are supplied through the authorised Creators API. We do not scrape or re-host retailer product photographs.

Important sources are linked in the relevant guide. See our editorial standards.