There are specialize brush basin (or pot) product out there, but I prefer to make my own disposal pot. Usually, I cut the plastic water bottle in half, and use the bottom half as the water pot. I made several V cut on the rim, so that I can brush the V cut with the cleaned brush to remove excessive water from it (for round brushes). Also, I glued old tooth brush bristle inside of the bottle and use it to remove the (acrylic) paint from the brush. You could rinse the brush with the inner wall of the bottle, but it requires more effort and likely damage the brush.

Also, you may want to put some rabble or gravel in to the pot to give extra weight to prevent spilling the water.

For organic solvent like mineral spirits, I bent some aluminum wire in spiral form and put inside of the bottle like this. It's less effective than tooth brush bristle, but due to the strong solvency of the liquid, it's okay, and it's better than using the inner wall of the pot. I was not sure whether any glue, tooth brush, or plastic bottle will be inert, so I used glass bottle and metal (probably aluminum) wire. They are probably okay for odorless mineral spirits, but may be not for true mineral spirits nor for turpentine.

To protect environment, I never clean the water pot. Instead just replace the water, let the pigments (and acrylic residue) stick to the plastic surface. And once in a while, just let the bottle dry, and discard it. It will be way better for the environment rather than draining all paint to sewage. Also, for organic solvent pot, the gravity will pull all oil paint pigments to the bottom, making the most part of the solvent clear enough. Then you can transfer clear part of the solvent to the another bottle for the reuse, and discard the remaining thick liquid in a paper towel, and discard it properly.