The part that is actually running, not the whole cistern
A toilet that runs is almost never a toilet that needs replacing; it is a five-euro seal on one of two parts. The fill valve lets water in and stops at a level; when it fails the cistern overflows quietly into the pan. The flush valve holds water back until you press; when its seal hardens the water trickles through continuously. Telling them apart takes a pencil mark on the water line and ten minutes. Buying the replacement then comes down to fit: the cistern opening diameter for the flush valve — 50 to 63 mm covers most — the adjustable height range, because one valve is sold to fit many cisterns, and for the fill valve, whether the inlet enters at the bottom or the side and at what thread. Dual-flush valves add a flush volume pair, usually 3 and 6 litres, which is adjustable on better units. We compare valve type, cistern opening diameter, adjustable height range, inlet connection and position, and stated flush volumes.
Fill valve · universal · telescopic outlet tube · stepless adjustment · stated quiet and fast filling
A sixteen-euro universal fill valve with a telescopic tube and stepless height adjustment — and a listing consisting of five hashtags.
Best for: A quick, cheap replacement in a common surface-mounted cistern, by someone who can see what they are replacing.
≈ £15 / 16 €
Fill valve · Geberit Type 380 · for surface cistern no. 240.700 · side entry 3/8 in · fill height set by turning the spindle · noise group I, DIN 4109
The manufacturer's own valve for one specific Geberit cistern — which is either exactly right for you or completely wrong, and the listing says which.
Best for: A Geberit surface cistern number 240.700, where a genuine part is worth paying for.
≈ $36 / £29 / 30 €
Fill valve · horizontal (side) entry · 3/8 in inlet · dirt filter · anti-water-hammer system · two seals supplied · 10-year warranty stated
A side-entry fill valve that states its thread, its inlet position and a ten-year warranty — plus a dirt filter and an anti-hammer feature.
Best for: A side-entry cistern where the mains supply is noisy or dirty, and where the person fitting it has never fitted one.
≈ 17 €
Fill valve · 3.6 l/min fill rate · 13 dB(A), noise group I · brass connection spigot · fits surface and concealed cisterns · NOT for TECE
The only fill valve in this catalogue that publishes a fill rate and a noise figure — and the only listing that tells you which cistern it does not fit.
Best for: A bathroom next to a bedroom, where the noise of a refilling cistern is the actual problem being solved.
≈ 17 €
Cistern set · TECE F10 fill valve, works 0.5–10 bar · armoured 3/8 in hose to 2019 · TECE A2 outlet valve for 13 cm cisterns · NOT for Uni 750
A three-part TECE service kit that publishes an operating pressure range and states, twice, exactly which cisterns it does not suit.
Best for: A concealed TECE cistern being serviced properly, where opening the wall twice is not an option.
≈ 94 €
