A white sediment underneath the urine for a while may be pus, celiac disease, crystallized urine and so on. 1. Pus urine: pus urine is often milky white, turbid, serious pus, most often seen in urinary tract infections. Urinary tract infections that cause pyuria are often divided into two categories: non-specific infections and specific infections, and are most commonly seen in renal abscesses, glomerulonephritis, urinary tract stones and other diseases. 2. Celiac disease: Celiac disease is a condition in which the urine is mixed with celiac fluid and makes the urine milky white or rice soup-like, containing a large number of fats, proteins, erythrocytes and fibrinogen. The common cause is filariasis, followed by retroperitoneal tumor, tuberculosis or trauma. 3. Crystalluria: Crystalluria refers to the phenomenon of salt crystals precipitating out of the urine and producing sediment. Causes may include concentration of urine due to recent decrease in water intake, decrease in solubility due to colder weather, and change in pH of urine. It can also lead to a white precipitate at the bottom of the urine. Urine put a while under a layer of white sediment may also be other reasons, patients should go to the hospital to take the correct method of treatment.