A popular solution in Bulgaria involves tee junctions on the cistern water input and specially made "gun" thing like you may be familiar with for some garden hoses, with the lever on a clamp that you open by squeezing it closed.

A friend who is familiar with these items from his time in Asia calls them "butt guns".

They are also really nice in Bulgarian bathrooms because it is standard practise in Bulgaria to tile the bathroom to the ceiling, the rooms are often quite small and shower, toilet and sink all jammed together in a tight space, you can use the hose to spray everything down quite safely without damaging any paintwork.

<3 bulgarian bathrooms. The best.