Be careful with well water...increased risk of parasites.
I'd stay away from Colace... it contains ducusate sodium which can increase the toxicity of any other drugs you may be taken, and can itself cause damage to the liver when used on a regular basis.
Yes, niacin is good for the digestive system...along with other B vitamins. Make sure that you are taking a B complex along with the added niacin... you need all of them. Other steps to lower cholesterol include garlic and psyllium fiber.