The feeling of swelling and pain in the lower back after drinking too much water may be related to hydronephrosis, pyelonephritis, renal insufficiency and other factors. It is recommended to consult a doctor in time to clarify the cause of treatment.1. Hydronephrosis: Drinking a lot of water will increase the amount of urine, which will aggravate the situation of hydronephrosis, and there will be swelling and pain in the lower back, accompanied by a decrease in the amount of urine, and ultrasound is needed to further clarify the situation. If there is hydronephrosis, it is necessary to limit salt intake, and early surgical treatment to relieve hydronephrosis, such as extracorporeal shock wave lithotripsy; 2, pyelonephritis: pyelonephritis is caused by infection of pathogenic microorganisms, and the disease itself can be symptoms of low back pain, and a large amount of drinking water may appear after the back of the distension, and in severe cases, patients may have a rise in body temperature, blood in the urine, and so on. After the cause is clear, after excluding contraindications, you can use quinolone antibiotics such as ofloxacin and ciprofloxacin to treat the disease, and encourage more drinking and urination; 3, renal insufficiency: water needs to be filtered through the kidneys, and when there is renal insufficiency, drinking a large amount of water will increase the burden on the kidneys, and it may cause the water to be retained in the body, which may result in oedema, lumbar bloating, waist sleepiness, and increase in urinary foaming, and so on. There may also be a feeling of distension and pain in the lower back. Further examination of renal function is needed. If the presence of renal insufficiency is diagnosed, it needs to be treated for the specific cause of the disease, and dialysis therapy, kidney transplantation and other treatments may need to be given if necessary, and sodium, potassium and phosphorus intake needs to be restricted in daily life. In addition to the above reasons, the feeling of swelling and pain in the lower back may have nothing to do with drinking water, but is caused by lumbar disc herniation, lumbar muscle strain and other diseases, and it is recommended to consult a doctor in time so as not to delay the treatment. In addition, the amount of water consumed should be controlled in daily life, and it is not recommended to drink a lot of water for a long time.