We don't know what was in your system but since it was green, it's
most likely poison. Hopefully it was not in the fresh tank but just in
the plastic water lines.
I just googled Mr Clean windshield wash and it clearly says
"may be fatal if swallowed".
This is why you should never put anything in the lines except pink RV
Flush and then flush again. Sanitizing is good but that won't get out the
taste and residual what ever it was. After the unit sits a few days open
a faucet and flush the pipes again and again.
Did you purchase the unit from a dealer or an individual???
And when you think about it, they maybe saved a whole couple bucks