over chlorinated water holding tank

I had my Mom's boyfriend do some work on my trailer. The work I asked him to do was done well... The only problem is he lambasted my fresh water holding tank with chlorine trying to be helpful. I have flushed the tank repeatedly (five times and counting) but there's still enough chlorine in there to burn the back of my throat when I attempt to drink it. I gave some to my dog when we had run out of drinking water and she puked all over the trailer (at least 3 times). Any way to neutralize the chlorine faster than with the fill and flush method?

Thanks