I use PLA and am able to get pots watertight, but not always..
My knowledge base on 3D printing is still what I would consider novice, but I know some basic calibration steps that help. Calibration of E-steps should get your extruder outputting the appropriate amount of filament, and to further calibrate I use those calibration cubes that can be measured with a micrometer for accuracy.

If all else fails, increasing the flow % in your slicing software might help.

I've heard there's certain types of paint sealers you can get that will work too but I've never tried them. I would however, perfectionism is not super important for pots, so using a sealer instead of wasting filament is a good choice, because filament can get expensive quickly, as I'm sure you know.

I successfully printed some robotic arms with actuating print in place gears. That took some serious calibration work, but machines with moving parts need constant tweaking.

What kind of printer do you use?

I'm on the Ender 3 V2.