Steam steriliser but wonder about the residue water.. my question is..?

You don't need to sterilize, but water left in bottles for a long time (more than just a couple days) is definitely a hazard. you are better off washing them in the dishwasher and letting them dry.

I worked with a guy who was permanently mentally handicapped do to an infection he got as a baby from a plastic container of some kind not dried completely. This is a rare case obviously, but those sterilizers don't really sterilize, and what is left grows in water. Esp. water with formula stuck to it.

Bacteria mold fungus etc. don't grow unless water is present. But once a bit of moisture is added to formula they go wild. They LOVE formula. Breastmilk not so much.

I'm just trying to tell you that you don't have to use a sterilizer, there is no reason to reduce the germs that much. But trapping water in a bottle and not letting it dry allows slow growing bacteria and fungus to reach very high numbers over time. Not a day, but say a couple weeks, a couple months and it becomes a real hazard. Esp. if a speck of formula was also trapped in the container, which is likely to happen sooner or later.

I would concentrate more on drying, less on sterilizing. Drying is FAR more important, since bacteria and mold simply can't grow on very dry things.

Don't worry too much about something being 'sterile'. In reality, few things in this world are sterlie. A breast that a baby feeds from is not sterile.

If you have washed and sterlised a bottle and then put it back together with clean hands then it is fine to leave it for a few days before you use it.

It's fine to dry your formula holder with kitchen towel.

Items stay sterile in a steriliser for 6 hours but as soon as you take the lid off then those items are no longer sterile. But as I said, it's not the case that only sterile items should be used to feed you baby. As long as they have been sterlised and then protected from contamination (i.e. by putting the lid on a bottle) then it is fine.

After you steralize your bottles, I would shake out any excess water and let it air dry. (doesn't take too long) Don't worry about keeping everything hospital room sterile...baby's need a little germs for their immune system.