What Adapter For

What thread is a washing machine hose in the UK?

Bosch gives the UK tap a washing machine hose screws onto as 3/4" (26.4 mm), the width of a 3/4" BSP thread, and Kuterlite’s washing machine valves have 3/4" BSP outlets. A rubber washer in each end of the hose makes the seal.

The washing machine valve

The washing machine valve sits on the water pipe behind the machine, and the hose screws onto its outlet. Kuterlite’s appliance valves have 15 mm inlets and 3/4" BSP outlets: the 15 mm end joins the pipe, and the 3/4" BSP end takes the hose. Kuterlite supplies blue and red discs to mark which valve is cold and which is hot.

What the makers’ manuals say

The machine makers call the valve the tap:

To check a thread with a ruler, outside tap thread size has a chart of BSP widths in mm. For how BSP differs from the US pipe thread, and which joints seal on a washer and which on tape, see BSP vs NPT.

The rubber washers, and how tight

Beko says to check that both hose connectors have a rubber seal in place, because the seals stop the machine and the hose leaking. Hotpoint’s manual says that if the fill hose is tight but still leaks, the rubber washers need replacing, or one is missing.

Beko says to do up both ends by hand, turning clockwise, and if a connector leaks once the water is on, to keep turning it clockwise until the leak stops. Bosch says to open the tap carefully, check for leaks and tighten if necessary.

Turn the washing machine valve off before you take a hose off, and check that a washer is in each end before you turn it back on.

US washing machine hoses

For US washing machine hoses, which are 3/4" female hose thread, see washing machine hose size (US). Before you fit a hose made for another country, check that its nut screws onto the valve by hand.

Common questions

Should I turn the washing machine valve off after each wash?

Hotpoint's BHWM 129 manual says to turn off the water tap after every wash cycle, to limit wear on the machine's water system and help prevent leaks.

How often should I check a washing machine fill hose?

Hotpoint's BHWM 129 manual says to check the inlet hose at least once a year and replace it at once if it has any cracks. It also says never to use second-hand hoses.

What water pressure does a washing machine need?

It depends on the machine. Hotpoint's BHWM 129 manual gives a minimum of 0.05 MPa (0.5 bar) and a maximum of 1 MPa (10 bar) for the water supply. Check your own machine's manual for its range.

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Washing machine fill hose, 3/4" BSP Washing machine hose washers 15mm washing machine valve

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Keep going

Washing machine hose size (US)BSP vs NPTOutside tap thread size (UK)Washing machine drain (US)

Where we get our information from

The valve size comes from a UK fittings maker’s brochure, the 3/4" BSP width from a fittings maker’s thread guide, and the hose thread and washers from three washing machine makers’ UK installation guides and manuals, and the US hose size from a US hose maker. Checked against published data from Swagelok, BrassCraft, Kuterlite, Bosch and Hotpoint (plus 1 more).

See all 6 sources
  • Swagelok, Thread and End Connection Identification Guide (MS-13-77)
  • BrassCraft, washing machine connector BL12-WA
  • Kuterlite compression fittings brochure (Aalberts IPS UK, 2024): appliance valves with 15mm inlets and 3/4" BSP outlets, blue and red discs
  • Bosch UK, How to Install a Washing Machine (installation hub): water supply hose to the water tap, 3/4" = 26.4mm
  • Hotpoint, BHWM 129 instruction booklet (19510952800_GB): 3/4 gas threaded connection, rubber washers, water pressure, inlet hose checks
  • Beko UK, How to connect your washing machine water hose to the mains supply: a rubber seal in both hose connectors, tightened by hand

General guidance from manufacturer and standards data. Parts vary by brand, so check the size printed on the package against what you measured. For gas lines or anything inside a wall, use a licensed plumber.