The flow sensor will pick up the flow of the garden hose as long as the hose is downline of the Wireless Flow Sensor. This will cause an alert that “Flow is detected without a program running”.
When you get that alert, take a look at the flow rate. If it is withing your anticipated amount used on your hose, you can usually ignore that alert. When you see something that is under .10 gpm then you can usually suspect a valve leaking.
There are other wired flow sensors that you can tie into your house that are rated for potable water. You can let the Rachio sensor do its job on the irrigation and add the other sensor just for your house.