Basically you must dispose of your surface water within your property and not divert into drains or run-off into the road. All good in theory, but I'd like to see the powers that made these rules try and get water to soak away in our area, which has thick impermeable clay and any hole dug between December and April soon fills with water! Just another annoyance for us landscapers and a smoke screen blaming the public for flooding..........rather like us being blamed for 'global warming' I suppose!