a smooth wall were provided the water sprayed on top of the container would flow to the wall container interface and stop the ribs allow the water to flow smoothly around the bottom of the container and then neatly collect back in the reservoir ribs 38 are preferred but not required a flat or curved wall or additional roller s could be used to provide support for the container as well as shown in fig2 c convex wall 37 a can be used if the container is rotated in a manner that it is pulling away from the wall and conversely concave wall 37 b can be used if the container is rotated in a manner that it is pushing into the wall both the concave and convex wall will position the container directly at the center of mass alternatively as shown in fig2 c both convex wall 37 a and concave wall 37 b may be used together for positioning the container further additional support structure may be provided to secure the container and prevent it from falling into the reservoir for example a clamp or netting may be provided which keeps the container in contact with roller 34 may be provided in the interior volume of the housing either attached to a side wall or from the underside of lid 50 for example.