What is the max height a washing machine can pump the water out at before it causes a strain and the wahers pump?
Each design/manufacture is sligtly different. Most say 5 feet is max, some will go up to 8 feet before crapping out. The one thing is the water in that hose will likely drain back into the machine once the washer shuts off, some have a small back check valve to help prevent that, some do not. Some washers ( Maytag is one ) have high volume pumps that can be purchased so they will do the 8 feet easily.
Another consideration is the washers speed, regular ( high speed ) moves the water out easier than the delicate ( slow speed ) does.