I do not know where the 8m water column to hide in the jacket, because:
This explains Wikipedia under point 'meter water column':
"According to European standard EN 343: 2003 (Protective clothing against rain) is a product with water column 800 mm waterproof (Class 2) and from 1,300 mm waterproof (Class 3) The Federal Laboratories for Materials Testing and Research (EMPA) in St. Gallen. in Switzerland expects that a functional material from a water column of 4,000 mm is waterproof. When sitting on damp surfaces, a pressure is built up, which corresponds to about 2,000 mm of water column. At the knees in a squatting position before pressing about 4,800 mm water column on the clothing.
Upper tents apply from 1,500 mm and tent floors from 2,000 mm according to DIN as waterproof. "
If the jacket with 8000mm of water column (really at little slips on the inner seam!) But already let rainwater in normal cycling, the information contained in the jacket can not vote.
No recommendation to buy, if you want to stay dry.