WANTED: Washed gravel for reed bed (grey water project) (Nunnery Wood WR5)

Washed gravel for reed bed (grey water project)
WANTED
Washed gravel for reed bed (grey water project)
Nunnery Wood WR5
DESCRIPTION
We are installing a vertical reedbed 660mm deep (860 long x 450 wide) to cleanse bath water prior to watering lawns, any surplus washed gravel (10mm and 20-30mm) or sand to create the necessary three filter layers, thank you!