This depends on how large the soakwells are that you wish to allocate to each downpipe and how much roof area is being drained into each particular downpipe. The industry standard requires that a downpipe with 100sqm of roof area should drain into 1000 litres of soakwell drainage. If your downpipe caters for 50sqm of roof area then you require s soakwell of at least 500 litres. These guidelines are based on sandy soil areas, in the absence of clay, rock and high water tables.
How deep should soakwells be?
Soakwells can be at surface level or buried. Buried soakwells are generally 300mm to 600mm deep to lid level. Generally soakwells that are at surface level are soakwells with grates, to allow surface drainage.
The depth of a soakwell hole will vary to compensation for the various dimensions of different sized soakwells.
What is the purpose of soakwells?
How big should my soakwell be?
Soakwell capacity and soakwell sizes are determined by the amount of rain water expected to flow into them. The soakwell size would also be impacted by the soil type, since sandy soil will drain water away much quicker than clay type sites. Soakwells and stormwater tanks should provide at least 100 litres of volume for every 10 square metres of drainage area. As an example, a roof space of 100 square metres would require a minimum of 1000 litres of stormwater drainage in sandy areas.
Are Plastic soakwells any good?
What are concrete soakwells?
What size soakwell do I need?