I have a medical room with 6 sinks total. There is no available drain inlet's so I need to pump the water up, and out to the main sewer dwv which is 30ft away. I was just wondering how you plumb back to back sink pumps for water discharge. It makes no sense because if one pump engages, it would shoot the water partially through the suction line, and it would end up in the other pump on the other side instead of going up the wall and out to the sewer line. Any help???