12 inches.
According to brunner and suddarths and saunders, the height of the colostomy irrigation bag should be hanging above the clients shoulder at around 18 inches. According to mosby, 12 inches should be the maximum height. According to lippinncots, 18 inches is the maximum height. According the the board of examiners, 12 inches should be the maximum height and an 18 inches irrigant height would cause rapid flow of the irrigant towards the colostomy. Therefore, answer in the local board should only be at 12 inches.