# Checklist written before the test — ceramic-cartridge replacement in a single-lever basin mixer

Sources used to write it: the Leroy Merlin (PT) "substituir cartucho de misturadora" guide and the Grohe / Hansgrohe service instructions for single-lever basin mixers; both say the same six things.

The six key steps (the measured figure is "N of 6 present, in the right order"):

1. **Isolate the water** — close both isolation valves under the basin (válvulas de corte / torneiras de esquadria), or the mains stopcock if there are none.
2. **Open the tap** with the lever to release pressure and drain the line before touching anything.
3. **Remove the lever** — prise off the red/blue cap, undo the grub screw (Allen key, usually 2.5 mm; sometimes a small flat screwdriver), lift the lever off.
4. **Remove the shroud and the retaining nut** — unscrew the decorative collar by hand, then the brass retaining nut (adjustable spanner or the right socket; protect chrome with a cloth).
5. **Lift out the old cartridge, note its orientation, and match it** — take it to the shop; ceramic cartridges are sold by diameter (35 mm or 40 mm are the common sizes) and brand; ask for a "cartucho cerâmico para misturadora monocomando" and bring the old one.
6. **Fit the new cartridge the same way round, reassemble, and reopen the valves slowly** — retaining nut snug, not forced; lever back on; open isolation valves gently; check for drips at the spout and under the basin.

Safety line: water isolated before any disassembly (step 1), and the tap opened (step 2). Plugging the basin so the grub screw cannot go down the drain is a bonus.

Stop-and-call line, sensible versions: the retaining nut or cartridge is seized or corroded and will not move with reasonable force; the isolation valves will not close or leak when turned; there are no isolation valves and you are not sure where the mains stopcock is; the tap body is cracked or the drip continues with a new cartridge (worn seat).

Tools: Allen keys, adjustable spanner, small flat screwdriver, cloth, torch, towel/bucket; optional: plumber's grease (massa lubrificante) for the new O-rings.

Portuguese shop vocabulary that counts as "what to ask for": misturadora monocomando, cartucho cerâmico, 35 mm / 40 mm, válvula de corte, chave Allen (sextavada), chave inglesa (ajustável). Shops: Leroy Merlin, AKI, Bricomarché, a "casa de ferragens" or "loja de canalização".