Good question, Eendhoorn. Generally speaking, Coda is about as carefree an instrument as you can get. There are lots of holes to air out the sound chambers, so they tend to dry out nicely. Also, the tough, non-porous, medical grade, food safe plastic that Coda is made from doesn't support bacterial or fungal growth well the way a more porous material might.
Yes, you can rinse your instrument with warm water. Just use common sense, so avoid boiling water, automatic dishwashers etc. And if you are a little careful so as to not to scratch the instrument, you can use the hose of a vacuum cleaner to suck out the moisture after you rinse it.
Now, I know from past inquiries that some of you tend to rinse your flute with water regularly. I'm afraid that I virtually never do. If I spill soup inside my Coda or drop it in the mud, I will though.
If you put Coda into a pocket with lint, or if you live in dusty area (near a dirt road, etc.), you can get dirt inside the toneholes. I suggest cleaning them out with a Q-tip (cotton swab) dipped in a little isopropyl (rubbing) alcohol. (Ethyl rubbing alcohol works well also.) The isopropyl alcohol evaporates right away, is a good disinfectant, and won't hurt Coda.
In the tips section at the beginning of your Coda book, I mention things like rinsing your mouth before playing Coda and polishing the windway once in a while. Rather than copy that info here, I'd rather have you review the tips in the book again. It's for your own good; you'll thank me someday! (Hey, I heard that wisecrack! Remember that this is a family friendly forum.
If you feel funny about playing your Coda after recovering from a cold, polish your windways (as indicated in the book tips), but use a little rubbing alcohol along with the folded paper sticks. Follow up with a dry polish, and blow out any fine paper dust.