Urinalysis is not recommended to use tap water as a substitute for urine, as it can affect the test results. Urine is a mixture of which 91-96% is water and about 6% solid components. The components include: organic matter (nitrogenous wastes: urea, uric acid, toxins, pigments, hormones, proteins, glucose, and other abnormal components), electrolytes (ions), inorganic matter (solids), and bacteria. And the test mainly measures solid components other than water. The main purpose of a routine urine test is to find out if the urinary system (kidneys, ureters, bladder, urethra) is damaged or inflamed and functioning abnormally. When there is an abnormality somewhere in the body, it will not be able to excrete the waste, or it will be mixed with the substances that should not be discharged in the urine, so through the urine test, you can assess the health status of the body such as sugar in the urine can assess the degree of diabetes, bilirubin in the urine can predict the inflammation of the liver and gallbladder obstruction, ketones in the urine can know whether metabolic acidosis occurs. If the patient is not feeling well, he should consult the doctor for examination and early treatment.