A few months ago our water was turned off to repair our sink. When it was turned back on, the water brought up some dirt from the pipes and sputtered out some air along with it. Each sink and shower had a few seconds of loud noises and dirty water, which would change the course of baths, showers, and hand washing forever. Each time we turned on a sink or bath, Lilli ran screaming from the room in terror. 
It took a LOT of convincing to take baths, wash hands and finally take showers. After what seemed like years, we got back to normal. No more cups at the sink to wash hands, no more bath only fights, no more bribery of new bath toys, paints and various other desperate attempts to get back our regular scheduled hygiene routines (see giant mixing bowl, plastic cups, and lots of bubble baths).
Recently, after a shower and a few curious questions about the differences between showers and baths, I decided to try and explain things a little better. With the help of some sandwich bags, building block cups, spoons and straws we filled up said giant mixing bowl in the sink and set out to explore. 
First, I filled two sandwich bags with water and sealed them tight. The first, we poked holes in and the second we cut a big hole in the corner. We talked about how the water comes from the same place but just comes out differently because of the holes. Next, we broke out some of her IKEA building cups, some of which have lots of holes, others just one. Same lesson, different methods.
Then, ice. We learned about how the ice melts, it makes the water colder, and it's very hard to catch as it floats on the water.
Finally, I took the floating conversations as an opportunity to talk about floating and sinking. How come the metal spoon floats and the plastic one doesn't? Why does the water bottle float empty and sink when it's full? What about quarters? And this straw? What about anything else within reaching distance?! I nearly had to drag her away from the sink, she had so much fun. While it was messy, two full towels of clean up, she learned a lot in what took only a few extra minutes to explain. Totally worth it.
