Bleach disappears fairly quickly. Leave a jug of tap water in the frig overnight and the chlorine will be gone in the morning. Municipalities actually have to inject extra chlorine to water lines that run too far from the wwtp so there is still some chlorine at the tap. There has to be around 2 or 3 ppm chlorine all the way to the customer. Your well will be fine in a day or you can buy some sodium thiosulfate to neutralize the bleach.