While startling, seeing crystals in the toilet isn't always a sign of disease. Here’s what you need to know.
Urine naturally contains dissolved minerals and salts. When urine sits in the toilet bowl for hours (overnight, for example), the water evaporates slightly and the temperature drops. This causes those dissolved substances to solidify—or crystallize.
A tiny bit of crystal sediment in the toilet, with no other symptoms, is rarely a concern—especially in the morning or after a hot, low-water day. But if you consistently see sand-like grains, or if you have any pain or urinary changes, call your doctor. A simple urine test can determine the crystal type and whether you need to make dietary changes or be evaluated for kidney stones.