Drinking less water and having foamy urine may be due to infection, diabetes, kidney disease and normal physiological phenomena. 1. Infection: urinary tract infections can lead to foam in the urine, accompanied by frequent urination, urinary urgency, painful urination and other symptoms. 2. Diabetes: When you have diabetes, you will have foam in your urine if you drink less water, and the foam is big and easy to disperse. 3. Kidney disease: primary and secondary glomerulonephritis, nephrotic syndrome, renal tubular disease and other diseases, renal function is impaired, can appear to drink less water, proteinuria and other symptoms, of which proteinuria is more often manifested as foam in the urine and long-lasting. 4. Normal physiological phenomenon: the formation of urine foam is related to the surface tension of urine. Drinking less water, will make the urine in the formation of fraction concentration, that is, the urine contains protein, glucose, a variety of secretion concentration, and then the urine surface tension increases, it is easy to have foam in the urine. There are many reasons for drinking less water and having foamy urine, it is recommended to go to the hospital for a clear diagnosis and follow the doctor’s instructions for treatment.