If she is playing in the garden, going on aparatus in the park, crawling around the floor, playing with presumably non-steralised toys and putting them in her mouth then you don't need to steralise anymore.
My baby had formular up to two as she was lactose allergic and I have to say while I didn't steralise her cup, I did boil the water purely because I could never get it to mix properly if I used cold water.
No one should drink water from the hot tap as it doesn't come off the rising main, you can only drink from the cold tap and like I say, I could never the milk to mix up properly with cold water and the thought of drinking cold formular made me feel sick so I always warmed it for her anyhow.
good luck with the change, I know it's always hard. I hope you had lots of fun at the birthay.
love
mimi