This is my sanke keg fermenter washer.
I used a small dish washer, took the sprinklers out and drilled a hole on the top, works pretty good, once I'll find a way to spray the water (spary ball , nozzle ,???) it will work great.
I just drpp a fountain pump in a rain barrel and pump warm soapy water up into an inverted keg (PVC wand goes up through the bung to the top of the keg) and let the pump run for about 20 minutes. As many kegs as you need to wash out, just turn the pump off and swap kegs. Once they're all cleaned, repeat with fresh water and you're ready to go.