Modeling sides of water tank

how I can model the sides of this tank (the sides I marked by red)?
which tool I must use?

I try different tools but no good result.

Initially, you could use the top face of the cylinder, inset it a few times, turn on proportional editing and pull out the very centre poly, which would give you the bulge. Then use boolean to add the two sqaure sections.

You could also try: Make a UV sphere or a round cube, flatten it to the proper shape, then chop off one half. See image.

Did a quick video, hope it’s of help:
https://youtu.be/2P6aAaZnCQ0

thanks.great help.

Glad it helped. :slight_smile: