It sounds like a unique situation! For tough toilet stains, consider using a combination of a strong toilet cleaner (like one containing hydrochloric acid) and a pumice stone for scrubbing. You could also try a commercial product designed for hard water stains or mineral buildup. When you check out the job, you might suggest a thorough deep cleaning instead of pressure washing, which isn't suitable for toilets. Good luck! kinght rooter do this.