Roof Drainage

I am in the process of drawing plans for a roof over my new deck. Can anyone give me some advice regarding the requirements for the disposal of water from the down pipes? Do all the down pipes need to go to storm water drains (this would mean a lot of digging which I would like to avoid) or can the discharge be used to water the garden (in Brisbane we are under very strict water restrictions)? Someone was telling me that a certain size pit full of certain size rocks was required to disperse the water over a larger area. Any suggestions would be greatly appreciated. I looked up the BCA and it didn't tell me anything.

May be different in your area but down here, you either need to connect to the stormwater drain, or you need the pit. Or you could put it into a tank. But then you have to do something with the overflow. Give the local council a ring and they should be able to tell you.

If you go the way of the pit, you can make one by digging a hole, cut a plastic drum in half and attach the stormwater to the top of it, then suspend it in the hole and back fill it with blue metal. It depends how well your soil drains though. Probably something in the order of a cubic metre would be plenty if it's a smallish roof.

The regulations require 'all storm water drainage to be held within the property or directed to a legal point of discharge' - i.e. council storm water line.

You can use whatever system you wish but at the end of the day you have to show [if required] that the system does permit water to end up in your neighbours property.

Hi Garves,

If your looking at installing a storm water pit then it needs to be a metre cubed and back filled with stones. As well as that it will an overflow point built into it. I looked at all this when we put in storm water run off when we bought our place a couple of years back. I got my info from the local council, same goes if your putting in a water tank. the run off is supposed to go into your storm water system. If you dont want to dig you could get the job dug out for you. Do you have access to the back yard from the the front of the house? A bobcat and chain digger could do it in no time for a couple of hundred dollars. Save you all that back breaking work all you need to do is to back fill.