i have a removable bottle on mine so i just pour it into that, i didnt see the point of having 1 where i needed to have a bucket as well.
however i then realised even with this i needed a bucket to rinse the sponge, after id gone over the foam before i washed it off.
in the end i bought agallon of turtle wax, wash and wax for pressurewashers so ill just top the bottle up with it and when it stops foaming top it up agen.