In my jurisdiction, it's against the law to have sump pump water directed to public sewer. Depending on the 'flow of things', if your home is inspected by a Municipal Inspector, it's possible you could be cited AND asked to remove the diversion. You need to find out what the 'requirements' are in your jurisdiction before you have the home inspected by ANYONE. For all I know, you may be OK to do what you're doing. Then again, maybe not. It's not the Buyer's H.I. you really need to worry about - It's the Municipal H.I. you need to worry about.