Bathroom fittings: what CP, brass and stainless steel actually mean

CP means chrome-plated, which describes the surface and not the body. A chrome-plated brass tap and a chrome-plated zinc-alloy tap look identical in the showroom and behave very differently after four years of hard water.

Brass bodies are the durable choice for taps and mixers and cost more for that reason. Zinc alloy is common at the budget end, and its failure mode is cracking at the threads rather than leaking at the washer — which means replacement rather than a new cartridge.

Stainless steel fittings resist corrosion better than plated finishes in coastal and hard-water conditions and have become common for sinks and increasingly for taps. Matt and black finishes are usually PVD-coated; PVD is genuinely hard-wearing, but a cheap painted imitation of it is not, and the two are hard to tell apart on a shelf.

Ask for the cartridge specification and whether spares are available separately. A tap whose cartridge can be replaced in ten minutes is a fifteen-year fitting. One that cannot is a disposable object with a warranty.

A tap whose cartridge can be replaced is a fifteen-year fitting. One that cannot is disposable.