Really Odd San Juan Express Question

Okay, so this question can either have a really simple, simple answer or could open up a discussion into the behind the scenes of Rio Grande narrow gauge operations. I was working as a brakeman on the Polar Express tonight in Durango and we had to service the restrooms before we could switch and tie up. Earlier while discussing our plan for switching in the "hot chocolate factory" (aka RPO #64) we began to wonder... where did the Rio Grande do the basic servicing of the restrooms on trains like the San Juan or the Silverton Branch and how?

How late did the restrooms just empty out onto the tracks and were tanks ever installed for the restrooms? If tanks were installed, when and where were they dumped? Durango, Chama, Alamosa... points in between. I know... this is a really odd question and not one that people think about normally, but it does come up. Thanks!