General question.

in the new update water blocks are announced so maybe... but for now, why do you mine near your base??? never near the base... far away, or on different island..

i think, in creative mode you can place "static" water. For survival no. For destroyed base with a bit of work you can save them. First you can place some raw materials (stone, dirt,sand, etc,,) to block water. After make a cavern under base and drill a hole to water go under base. All work depends how big is base. So for a relative small base it's easy to fix. For big base ...

When do mining what careful what hit. If reach gravel/sand and deep is under 90 height, stop asap! Keep a rake on hot bar. If fast and have a bit of luck, you can ''repair" accidentally hole if you are fast enough before water fill all.

I don´t think the Blocks in the Java version could hold back water. But then again, in Java you had 2 very different types of Blocks. One was a static one that you could not rotate, place or resize freely. And then there were planks and beams, which you could rotate, place and scale freely.

And in Java the water behaved different. Wasn´t it like Jelly? It´s too long ago i played Java

If you want water against regular blocks use creative static water blocks, they will function as a dam that looks like water fooling you into thinking it is the regular blocks acting as a dam.

I also used static water blocks to give the appearance that a pond is flowing down hill, will need to update when the area block placement can be rotated next patch as it looks a bit unnatural.

I have rebuilt my mega dungeon several times and finally buried the entire thing in stone using creative block area cutout to make sure the rooms are encased in stone within the walls. Still have not taken down the dam down as I fear a hidden missed leak somewhere from an errant pickaxe.