That’s what I’ve done…
- Put a compression tee valve with washing machine fitting (3/4 bsp) in the cold water supply under the kitchen sink
- Connected a 3/4 bsp solenoid to it
- Powered the solenoid via an Aeotec smart switch with an isolator switch from the dishwasher plug socket
- Put a reducer in the other side of the valve down to a 4.6mm barbed fitting
- used the Gardena micro drip irrigation system with their 4.6mm hose connected straight in via a hole through the wall and used the micro drip hose for ~20m of flower beds
I’ve written a few pistons in CoRE using a weather Device Handler to turn the switch on in the morning unless it’s rained more than 1mm the day before or that morning. I’ve got one that ensures it’s switched off after an hour no matter how it was switched on.
Works great all for about £150 including all the hose, fittings, isolator switch, clips, etc