The most common problem that affects the urinary system organs is a urinary tract infection. It can be caused by many things. The most simple cause of the UTI is not drinking enough water. Although UTIs are very simple to identify, they can also be mistaken for other disorders. An ordinary symptom of a UTI is burning while urinating. If there is blood, a person might have cystitis, which is an infection of the bladder. UTIs can also be mistaken for urethritis. It has all the same symptoms of a UTI, but it caused by a sexually transmitted infection.