Based on your description, you seem to have gross hematuria, in which blood is visible to you. There are many possible cause of blood in urine (Hematuria), some of the common causes are: Urinary tract infections, stone, prostate enlargement, Kidney disease, Cancer, Medications (Common drugs that can cause visible urinary blood include aspirin, penicillin
, the blood thinners warfarin and heparin), Strenuous exercise.
Most commonly, the causes are simple and minor like infection but still the exact cause of hematuria needs to be ruled out. You will have to visit an urologist, they will do series of test such as urine test, IVP, ultrasound or CT to pin point the exact cause. It is not possible to predict the cause just on the basis of hematuria, further investigation is the only reliable way to make the final diagnosis. Since you do not have any urinary symptoms, uti is less likely, but prostate issues can present like that.
Please let me know if you have any other question.