Can I have polished concrete in my bathroom and shower?

Technically yes, and many people do. Depending on the system you are wanting and the finishing options you would like there may be some considerations for slip, consistency of exposure or ensuring council approval, however with the co-operation of your builder and forward planning, generally we can achieve the outcome you are after. Keep in mind polished concrete should not come into contact with acidic or alkaline agents so consideration may need to be given to what products are used in these areas such as soaps and shampoos etc.