Can I clean my sport loop watch band with soap and water?

I think it would be ok to do as long as you use mild soap. You may want to visit the below link on iWatch care:

Cleaning and wearing Apple Watch(Document Type: Document) Nov 18, 2016Learn about materials in your Apple Watch, and how to clean it. Get helpful tips on avoiding skin irritation...https://support.apple.com/en-us/HT204522

You might want to remove the band from the  Watch before giving it a thorough cleaning. When the bansd is dry, put it back on the  Watch.