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How to connect a 3/4 hose to an outside tap

Updated: 22 October 2026

The nut is cross-threaded, the gun end has blown off, or the hose is sitting in a bucket under the tap. How to connect a 3/4 hose to an outside tap is a joint, a washer, and a tail that matches the bore, then a hose you disconnect when you finish. Hand-tight on a flat washer is the tap end. A 19 mm wall needs a 19 mm tail, not the 12.5 mm click fitting already in the shed. Updated on 21 October 2026, the steps follow Hozelock's measuring guide, HomeServe's leak advice, and Water Regs UK and WaterSafe notes. Which hose you bought is the [garden hose 3/4 inch comparison](/hub/garden-watering/garden-hose-3-4-inch).

The nut is cross-threaded, the gun end has blown off, or the hose is sitting in a bucket under the tap.

Our top picks

Faithfull Faithfull 19 mm 30 m

Best overall

Faithfull Faithfull 19 mm 30 m
6.1/10about £43.00
View offer
Flexi Hose Flexi Hose 50 ft expandable

Rank 2

Flexi Hose Flexi Hose 50 ft expandable
7.4/10about £19.99
View offer
Lukiegale Lukiegale 50 ft expandable

Alternative

Lukiegale Lukiegale 50 ft expandable
6.4/10about £23.79
View offer
On this page
  1. 1.Measure the tap before you buy another nut
  2. 2.Fit the connector and stop the drip
  3. 3.A 19 mm hose needs a 19 mm tail
  4. 4.Backflow, draining, and when to stop

Measure the tap before you buy another nut

BSP sizes are nominal. Hozelock's guide puts about 26.44 mm across the thread at 3/4 inch BSP, and about 20.99 mm across the thread at 1/2 inch BSP. About 26.4 mm is the tap thread, not a 19 mm hose. Their 2175 connector includes a 1/2 inch adaptor. A listing that mentions US taps, as Flexi Hose's bullet does, is a reason to measure. Lukiegale's bullet tells you to remove an adaptor for the larger tap. About 21 mm is a 1/2 inch BSP tap. About 26 mm is 3/4 inch BSP, and the adaptor has to come off. The bore is a different decision, set out in the 19mm garden hose buying guide.

Fit the connector and stop the drip

Seat a flat washer in the nut so it lies flat, then screw the connector on by hand until it is firm. A drip at the hose joint is often the washer or the O-ring, which is HomeServe's account of this leak. Tightening further crushes the washer and the drip stays. Do not wrap PTFE tape around that joint. Open the tap with the gun closed and look at the nut for a minute. If water appears between the nut and the tap spout, turn the water off and replace the washer rather than adding another half-turn. A drip from the tap body, with the hose taken away, is a different fault. HomeServe treats that as the gland or the tap washer. It is not cured by a new hose.
Faithfull Faithfull 19 mm 30 m

Testsieger

Faithfull Faithfull 19 mm 30 m
6.1/10about £43.00
View offer

A 19 mm hose needs a 19 mm tail

The hose-end fittings in the Hozelock system that includes the 2175 are for 12.5 mm and 15 mm hose. They are not a 19 mm tail. A 12.5 mm click fitting on a 19 mm wall grips poorly, and the pressure that holds a narrower hose pushes this one off. Reviews on the short RUCUDIM lead describe connectors blowing off Hozelock fittings. Faithfull's 19 mm listing is the hose only. One reviewer fitted it with a 19 mm Gardena connector. If you have bought that coil, or the Vartco coil that also states 19 mm, buy the matching tail before you open the tap onto a 12.5 mm gun. An expandable sold with a 3/4 inch nut can still have a narrow hose inside that nut. The named options are on the best 3/4 inch garden hose page.

Backflow, draining, and when to stop

A hose left in a butt, a pond, or a bucket can pull dirty water back toward the main if the pressure drops. WaterSafe's advice is to keep the end out of stored water, disconnect when you finish, store the hose out of the sun, and run stale warm water to the ground before you spray. Water Regs UK note that on many post-1999 installations the double check valve is indoors. Do not assume your tap already has one because the house is fairly new. Call a WaterSafe plumber if you cannot find a double check valve, if the hose must sit in fertiliser or a pond, or if the tap still leaks after the hose is removed.

Common questions

How do I tell 3/4 inch BSP from 1/2 inch BSP?
Measure across the thread on the tap. Hozelock's chart puts 3/4 inch BSP at about 26.44 mm and 1/2 inch BSP at about 20.99 mm. The 2175 connector includes a 1/2 inch adaptor, so check you have not left that adaptor in the nut. About 26 mm is the tap. It is not the internal bore of the hose.
Why does the connector leak after I have tightened it?
The washer or O-ring is the usual cause of a drip at the joint, which is HomeServe's description. Turn the water off, refit a flat washer, and stop at hand-tight. Leave PTFE off that face. If water comes from the tap body with the hose removed, a new connector will not stop it.
Will a standard click fitting grip a 19 mm hose?
Not if it is the 12.5 mm or 15 mm tail used on ordinary UK click systems. Hozelock's hose ends in this tap-connector system are those two sizes. A 19 mm wall needs a 19 mm tail. RUCUDIM reviews in this set, on a 2.5 m lead, describe fittings blowing off Hozelock connectors. Faithfull is hose only, so the 19 mm connector is a separate piece.
Do I need a double check valve?
You need the protection your water undertaker expects for a hose union, and you should not assume it is already there. Water Regs UK note that post-1999 installs often have the double check valve indoors, and the undertaker judges the fluid category. If you cannot see that valve, or the hose will sit in fertiliser or a pond, stop and use a WaterSafe plumber.
Can I leave the hose in the water butt?
No, not while it is connected to the tap. WaterSafe's backflow advice is to keep the end out of stored water, disconnect after use, and flush stale water before you spray. A hose draped into a butt, still on the mains, is a path back toward the supply if the pressure falls.

Related pages

Hosepipe ban and your garden hose

Garden hose 3/4 inch

Best 3/4 inch garden hose: who the 19 mm listing is

19mm garden hose buying guide: decide bore and length

1/2 vs 3/4 garden hose: flow, weight, and fittings

Sources

Public UK sources for tap size, hosepipe bans, pressure and backflow. Shelf prices, stars and review counts are the amazon.co.uk figures captured for these nine listings on 21 October 2026. Last checked 22 October 2026.

  1. Hozelock, how to measure your tap (retrieved 21 October 2026)
  2. Hozelock, 3/4 inch and 1/2 inch outdoor tap connector (retrieved 21 October 2026)
  3. Water Industry Act 1991, section 76 (retrieved 21 October 2026)
  4. Ofwat, hosepipe bans and non-essential use bans (retrieved 21 October 2026)
  5. Ofwat, water pressure (retrieved 21 October 2026)
  6. Water Supply (Water Fittings) Regulations 1999, Schedule 2 (retrieved 21 October 2026)
  7. WaterSafe, hosepipe backflow (retrieved 21 October 2026)
  8. BBC Gardeners' World, best garden hoses (2026) (retrieved 21 October 2026)