I have a congenital bicuspid aorta and moderate regurgitation. i am 61 and have no symptoms. does taking niacin and drinking a lot of water help?

No: Drinking 'a lot' of water is not recommended. You're valve is abnormal (and has been since birth), in the future you may need a replacement but it sounds like you don't need one now. You will need a new valve when aortic regurgitation becomes severe or when you develop symptoms. Niacin and other medications to control the cholesterol have been studied and don't prevent disease progression.