It seems to me
That you might be able to deal with the problem through an overhead water tank.
Just, at 1Kg/l...well, let's see. That's about 175Kg per machine per load...X50...8,750Kg...is 19,250lbs.
Heavens. That is a bit of a load, though the volume needed would not be so dreadful.
Drains, oh, my....
Electrically, hmm. Lee has it right. Now, to save copper, you could run split phase outlets like in kitchens back in the 1950's began doing. Still, if we assume 1KW per machine and you run all 50 at once, you are in the range at which power companies require the installation have active power factor control and be subject to remote cut off by the electrical company (rolling black outs)....
Silly question, but what's the direction you want to go here? It sounds interesting...I'd love to see and hear 50 thumpers thumping (in PANK!)