What is urine composed of?

Water ,waste,salts: Urine is made from blood filtering through the kidneys.Waste which are several chemicals generated from what you eat are eliminated , also excesss water and salts such as sodium and pottassium are also regulated.Acid base balance is also one of the many functionsof the kidney acheived from making urine.

Mostly water: Urine is mostly water (about 95% water), however, the rest of the contents of urine can vary depending of what you've eaten, drank, breathed or been exposed to. The remainder of urine usually consists of urea, uric acid, ammonia, hormones, dead blood cells, proteins, salts and minerals, and toxins.