If you had the covers fitted would you have noticed the 3" of water? or would you have missed it and had a flood costing hundreds of pounds to rectify (if indeed you can ever recover the electrics)?
I have had 3 floods in the past in Passats, these have very good coverage of the plenum chamber as the cover is one complete unit, it also has a soft rubber seal on it, but they still flood as the stupid valves get blocked with silt.
I advise removing the valves and not wasting money on covers that perform no useful function, but get in the way!