My panniers, water (1 litre), tools and pump, rain gear, and lock add 13 pounds to any bike they go on... my recumbent (one of my main commuters) curbs out at 30 pounds with fenders, lights, and a handlebar bag that carries it's spare tubes.
I rarely travel light, it makes no significant difference to my commuting time and sometimes I use the Extrabike which weighs 50 pounds before it gets any added gear.... at times I just carry a small hydration equipped backpack (10 pounds with gear) and ride the road or mountain bikes which weigh 21-26 pounds.
My Moulton (the other commuter) and usual gear weighs 35 pounds, everything I need for the day fits in the Carradice bag.
A lock and water are going to add 4-5 pounds to any kit and are the most significant extra weight I carry regularly.