Can a long refill tube can cause the toilet water to run?
One cause for a running toilet is that the refill tube continuously pumps water into the bowl. This happens when the tube is too long. It isn’t positioned correctly in the overflow tube. To shorten a refill tube, pull the tube out of the overflow. Hold it just above the opening of the overflow. Trim it off there. Clip it to the side of the overflow tube to keep it in place.