An enema includes a liquid in a dispenser having a bottle, a nozzle attached to the bottle, and a valve. The valve may be a membrane having a slit and a thickness of at most 0.90 mm. The valve may be attached to the bottle or it may be attached to the nozzle. The enema can be administered more easily, with a lower amount of force. A method of bowel cleansing includes inserting the enema into a rectum and applying a compression force to the enema bottle.