The simple fact that your water hose is designed to attached to water sources ONLY outside of your home not inside. So, you must find the right adapter to access water inside your house.
The easiest location is your kitchen sink. We recommend using the “Y” adapter as well so that you can leave your water hose attached and still get water from your kitchen sink by opening and closing the valves on your “Y” adapter. The end cap goes on the pool end of your hose so you can set your hose outside of your pool and not worry about water draining from the hose onto your floors.
You can also use a shower adapter to access water from your shower pipe (the pipe coming from your wall that your shower head attaches to) for filling your pool but keep in mind that this water source is more complicated. You will need to remove your shower head and have the right tools to do this. You will also need plumbers tape and plumbers putty to put the shower head back on to not have leaks.
Blessings in birth,