Outlet size for a 3/4" Garden tap?

[GCM]

I'm trying to replace an old outdoor tap that is connected to some MDPE piping (the house is built on an old road depot and it was an existing installation). It has a "Round Mixer Tap Connector" for the hose but it leaks like crazy and when I took the tap off to have a look, I was sure there wasn't a double check valve. The tap says BS1010 3/4" but that's only for the inlet; the outlet is something like 7/8".

The trouble is that while looking for a replacement, a lot of sites give me the impression that a 3/4" tap won't fit a hozelock type adapter, regular garden taps seem to have 1/2" inlets, and most suppliers don't specify an outlet size.

I was wondering if there is a standard corresponding tap outlet size (like how a 1/2" inlet tap usually has a 3/4" outlet/hose union)? Secondly, the tap is currently used with a sprinkler and I was wondering if the check valves, or if I were to try find an adapter to 1/2", would cause a significant decrease in the water pressure?

 

[JCplumb]

Standard bib tap has a 1/2'' connection to the wallplate and a 3/4'' threaded spout that hoselock fittings are designed for. A hoselock adapter will fit a standard bib tap.

 

[Best]

Your tap is perhaps a 3/4" tap. Most new standard outside taps are 1/2" inlet, but 3/4" outlet thread for standard Hozelock fittings and any other brands.
You can get adapters (usually plastic bushings) to change from your tap thread to the modern 3/4"
You can get 1/2" or 5/8" or 1" that all change you over to 3/4"
If your tap is 3/4" thread, then you need an 1" adapter available from some DIY kits

 

[Best]

Here is a 1" to 3/4" one,

1 Inch to 3/4 Inch Threaded Adapter | Easy Watering

 

[GCM]

Your tap is perhaps a 3/4" tap. Most new standard outside taps are 1/2" inlet, but 3/4" outlet thread for standard Hozelock fittings and any other brands.
You can get adapters (usually plastic bushings) to change from your tap thread to the modern 3/4"
You can get 1/2" or 5/8" or 1" that all change you over to 3/4"
If your tap is 3/4" thread, then you need an 1" adapter available from some DIY kits

So a 3/4" tap is likely to have a 1" outlet? I shouldn't reuse the existing tap because it can't stop a backflow but it's a bit easier if I know a new tap's outlet will be 1".

 

[chris watkins]

So long as the sprinkler is an above ground type (i.e. not a pop-up) you should ensure that a double check valve is installed pryer to the new tap.

If you can get this inside your house to provide it with protection then that is the best option as required by the Water Regulations 1999 if it has to go outside as the tap is on a post it needs to be protected & insulated against frost damage.

Taps with the check valves built-in are for replacement purposes only I am afraid.