none of this stuff actually makes your jacket/trews waterproof - the liner or bonded membrane does that. Tech wash and all its variants adds water repellency to the outer of the garment to stop the fibres soaking up water. All the tech wash stuff is really needed for is to aid breathability by ensuring the outer surface is not wetted out such that water vapour cannot evaporate through it. In doing so it makes the jacket/trews much more comfortable to wear, warmer (as water is not evaporating and cooling) and quicker to dry. Just saying.