Question: What are the physics behind the making of pee

Carly Bingham answered on 7 Apr 2026:

The most important organs for making pee in the human body is the kidneys! Most people have two kidneys, which sit just below your ribs, towards the back of your body. All the blood in your body passes through your kidneys about every half an hour via your arteries. Your kidneys act as a filter, removing any things that aren’t supposed to be there (waste) as well as any extra water. The waste and water together make urine (pee) which is transferred to your bladder via tubes called ureters, ready to be peed out. The newly cleaned (filtered) blood returns to circulation via your veins.

Fun fact – often when people have a kidney transplant, unless there is a problem, the old kidneys aren’t removed so some people have more than two kidneys inside them!