: You realize that by piping the driveway water to the creek you are polluting it with the stuff that will wash off the driveway, and you are also violating the law in most areas that prohibits you from disposing of rain water off your property.: : I have a driveway drain to pipe 200 feet to a creek. What should be the drop per foot for the drain pipe ? And how can I estimate the needed diameter of the drain pipe ?There is no other drainage system in the area. All the water that washes across the drive flows normally into the creek. Except the local municpality has now built up the street trapping the larger flows of water that occur during a heavy storm. The water level rises flooding the drive, then the garage and then the basement of the house. The basement sump pump then pumps the water out into the creek. This driveway drain will simply bypass the house flooding which causes several hundred dollars damage each time it occurs (2-5 times a year). I dont know of any laws that might be applicable, everyones driveway wash ends up in the creek whether they realize it or not.