Teresa, there is no maximum distance for a septic tank separation from the house. Just remember, “SEWAGE RUNS DOWNHILL.” Also remember to install cleanouts in the sewage pipeline when the distance between the house and the septic tank exceeds 100 feet. So if the new septic tank will be 150 feet from the mobile home, then a cleanout should be installed within 3 feet of the mobile home, and another cleanout should be installed at about 75 feet.
John Aldrich (Septic Tank Yank)
Septic System Consultant
Timnath, Colorado USA