Find the filter that fits your jug

Almost always because you have crossed the transatlantic divide. Brita is two separate companies sharing a brand: Brita GmbH of Germany sells MAXTRA+ and MAXTRA PRO cartridges to Europe, the UK, Australia and most of the world, while Brita Products Company, owned by Clorox, sells Standard, Elite and Stream cartridges to the United States and Canada.

The two cartridge families are physically different shapes and there is no adapter. A US Brita Standard filter will not go into a European Marella, and a MAXTRA PRO will not go into a Brita Everyday. This happens most often when someone orders from an international marketplace listing without noticing which market it ships from.

The second most common cause is a Brita Stream pitcher. Stream filters fit only Stream pitchers, and Standard and Elite filters do not fit them at all — that is a fitting difference within the American range itself.

Yes, in both directions. Brita kept the fitting identical when it replaced MAXTRA+ with MAXTRA PRO, so any jug that took one takes the other, and cartridges left in the cupboard are not wasted.

What changed is the range rather than the fitting. MAXTRA PRO is sold in grades — All-in-1, Limescale Expert, Pure Performance and Extra Lime Protection — so the decision shifted from which cartridge to which version of it. All-in-1 is the sensible default.

Yes. Every American Brita pitcher and dispenser that takes the white Standard filter also takes the blue Elite filter, with no modification.

It is usually the better buy. Elite runs for 120 gallons against the Standard's 40, and it is certified to NSF/ANSI 53 for lead reduction, which the Standard filter is not. Three Standard cartridges cost more than one Elite and do less.

The exception is the Stream range, which takes neither.

For taste, generally yes. The MAXTRA fitting in particular has a large market of compatible cartridges — Dafi Unimax and the supermarket and Amazon own-brands among them — that are made to the same shape and contain the same basic activated carbon and ion exchange media, at roughly half the price.

What you give up is any independent statement of what the cartridge reduces. There is no certification behind a generic, so if you are filtering because of a specific contaminant rather than because the water tastes of chlorine, the generic is not a substitute.

There is one practical failure mode worth knowing. Third-party fit tolerances are tighter than the original, and a cartridge sitting a millimetre proud of its seat lets unfiltered water run straight past the filter and into the reservoir. It looks like it is working. Seat the cartridge firmly and check it is flush.

Take the cartridge out and look at its shape rather than at the jug. A tall cartridge with a keyed collar and a wide flat top is the MAXTRA family. A squat round white cylinder is the discontinued Brita Classic. A tapered cone with a mesh base is the American Brita Standard fitting.

If it is a Classic, you are at the end of the line: the range is shrinking and a new jug plus a year of cartridges usually costs less than stockpiling a discontinued part.

Most jug bodies also carry a moulded model name on the base or under the handle, which is the fastest route to certainty.

Almost none of them do. Fluoride is a very small, very stable ion and activated carbon — the medium in nearly every jug cartridge — does essentially nothing to it. Brita, PUR, Philips, BWT, Laica, Aquaphor and every generic make no fluoride claim, because there is none to make.

The exceptions are ZeroWater, whose ion exchange resin reduces fluoride as part of stripping dissolved solids generally, and Clearly Filtered, which publishes specific fluoride reduction figures from third-party laboratory testing. Both are more expensive to run than a conventional jug.

Serious fluoride removal normally means activated alumina, bone char or reverse osmosis, none of which fit in a gravity jug.