Am trying to find way to plumb washing machine into rented premises with no existing w/m plumbing. Have to do it temporarily into kitchen sink (kitchen plumbing is hidden behind existing cupboard) and want to plumb w/m inlet from kitchen tap (it doesn’t have a thread) with a rubber tap connector. AT one time these were fairly common place but can’t find where to locate them.
You can still get these piercing valves, ask at your hard ware store for a kit to install an ice maker fridge.
But piercing valves leak, and the tiny hole they make won’t pass much water, it will take a long, long time to fill a washer.
I suspect that if you unscrew the aerator form the faucet, you’ll find a set of threads where you can attach a hose adaptor, also available from the hardware store.