50 metres is just an example, tank may only be 2 metres from house, depends on the owners choice, size of tank, slope of land whatever. Not one has said how they clean, drain these pipes that are underground.
As for a 'wet area' that slows the water to allow sediment to fall out of suspension,
would have to virtually stop flowing for that system to work.
If it's so efficient, even in heavy rain, they should patent it, and sell it to the water corp.
Forgot to tell old mate, a horizontal downpipe, is just that. Runs under the eaves,
or the side of the garage wall, like I did, with around 75 mm fall, in 6 metres.
