1/4 cup bleach to 15 gal H2o.
Run thru all lines (including water heater, ice maker, washer, head, shower etc.), slosh in 1/3 full fresh tank by moving.
Let sit minimum 2 hrs (we do 4)
Drain and flush.
We flush second with straight vinegar (thru winterizing port) and let sit 8 hrs to dissolve the minerals. We don't put much vinegar in the fresh tank just to fill the bottom and let splash around before draining. Yes we use 13gal total of vinegar to also allow filling the (drained) water heater as well.
Don't forget to remove any filters that will pass the "juice"
Don't forget to turn off the water heater whenever empty.
The vinegar offsets/neutralizes all bleach residual smells so first flush is minimal.
We let the flush water stay in the balck/grey tanks until ready to dump later when full. We drain the water heater before adding the "juices"
1999 Newmar Mountain Aire MADP 4080, Cummins ISC 8.3L, Allison, Spartan MM IFS, Howard Power Center, Chev Trailblazer LTZ Towed w/ BlueOx rigging, Segway X2.