I would like to add a washing machine drain to our laundry area. Currently, the drain goes into the sink but I am looking for a cleaner method. Looking at the picture, the sink drains into the largest pipe and has a vent that is the left verticle pipe. The middle verticle pipe goes into the ground. The right verticle pipe has the sink drain into it along with a bathroom and kitchen from upstairs. Is there a way I can tap into one of these pipes to add a drain? I'm hoping I can add it to the middle verticle pipe.