Is it ok just to clean my new pierced ear with water?

City water, yes: If municipal running water, in general, yes--studies have shown it can be better for the wounds we see in the er, due to volume available, so don't be stingy. If scab/crust, should use half hydrogen peroxide and water to help prevent the build up.

Use a salt solution: Use a sea salt solution as an alternative to a store-bought cleaning solution. Use 1/8 teaspoon of salt per 8 oz water. Wash hands before and use a cotton applicator to clean the pierced ear.

Options: Hydrogen peroxide, chlorhexidine, or sterile water and soap may be better.