This has been on the "I need to do that one day" list. The extra time I have on my hands at the moment finally gets it off that list.
This water outlet feeds water to my back gardens. It was a single 15mm tap that had seized open, something I'm sure I could have repaired but I wanted a separate outlet for the drip irrigation system and a general hose outlet.
The solution was to fit a 20mm tee with a 15mm/20mm threaded adapter to the existing outlet. I then went with two new 20mm taps, one fitted with a automated timer for the drip system, the other as a general hose outlet.
This is the full extent of my plumbing ability.