On our Everest Base Camp Trek, the teahouses we use have western toilets. The rooms in the luxury lodges and teahouses at lower elevations have an attached bathroom and hot water shower. Facilities may be somewhat basic at higher elevations, and you may have to share a bathroom with other travelers. In extreme cold, the water in the sink may freeze, and you may need to use an Asian toilet outside. Always carry toilet paper rolls with you. Taking enough toilet paper rolls and hand sanitizer for the trip is best.