Check your garage, I'm pretty sure by code there has to be a filtered water pipe/hose next to the water tank. Just run a hose out side from there, and don't use the mexicans hose.
2008 M3 Sedan + catless + Tune
2012 CLS63 AMG
2014 M6 Coupe + catless + KW V3
2015 Porsche GT3