Water Turns To Source Blocks When Deactivating Bubble Column

I use a Samsung Galaxy Tab A 8.0- and I was experimenting with bubble columns thinking of a way to create a two way elevator. Anyway, I started with only one source block placed at the top of the water tube, then added the soulsand. I removed it and replaced it with a regular solid block. I then removed the top water source, but the rest of the water didn't disappear. Apparently the were all source blocks.