Like said above, it depends on where YOUR drain(s) is/are located. Most sites I have been on the sewer drain is within 10 feet laterally of where you are expected to place your unit. From there it can either be forward toward the middle of the site or back in the site further than you can get the unit. Generally if you measure the distance from your drain to the rear of your unit and add 10 feet you will have enough to reach most sewer hook-ups. Unless of course your drain is right at the rear of your unit. Then I would go at least half the length of the unit.