When you're running dual wands, the waste tank fills up quickly.
We cleaned our church carpet last Friday, dual wands ( one wand with a #8 flow, and the other was a 15" Zipper SS). Our truckmount ran for 4.5 hours without a stop because the APO kept us movin'. With this setup, we are able to use a smaller waste tank giving us more room in the van. We are not using extra fuel driving around with a full waste tank either.
How can some of you make it all day out cleaning and not have to dump your waste tank?