There is no holding tanks except the water tank under the sink. The gray water from the sink empties on the ground. There is no use for black tank due to not having a bathroom. They are great basic trailer, tows like it's not there. The only problem with it is that there is no outside electric plug and no outlets on the right side (inside). The only light
inside is over the rear door which means you have to get out of bed to turn it off. On mine I installed 6 led 12v lights
under the upper cupboards which gives us lots of light
. I also installed outlets on the side of the cupboard. I have never seen another one like it so it draws a lot of attention where ever we go.