I had been using Milton and found it fine but everyone urged me to get a "proper" steriliser so we bought a microwave steam steriliser. It sterilises 4 bottles at a time and says that they stay sterile for up to 5 hours. If you are only meant to make up feeds as and when they are needed, and a baby is feeding every 3-4 hours, you will never need four sterile bottles in five hours... Or, if immediately after sterilisation you assemble and close the bottles, do they stay sterile for longer? If so, how much longer? Also, it's in the microwave for 5 mins, then it says to leave it sit for 3 mins.... is that 3mins just to give the equipment time to cool so that you don't scald yourself while removing it, or is that part of the time needed for the steam to do its work and sterilise the stuff? Sometimes I don't wait the 3 mins as baby is screaming for a feed.