What are the requirements for hooking into the City of Omaha's sewer system as opposed to replacing an old septic tank with a new septic tank?

We are considering buying a house that currently has a functioning 1000 gallon septic tank that was homemade from concrete cinder blocks at an unknown date prior to the establishment of city codes regulating septic tank specifications. It is currently functioning, the appropriate size for the house it services, and has an excellent 20 year history of annual pumping and propolateral testing as verified by the service provider.
It will at some point however reach the end of its useful life and need to be replaced. We are wondering if at that time we will be looking at the cost to replace it with a new septic tank, or if the city will require us to trench lines and go into the public sewer system. I believe this varies with property proximity to city sewer lines but have been unable to determine what the distance and/or other requirements are. The house is within city limits; its street address does not have city sewer, but Fort Calhoun Road does which is approximately 400-600 feet from the property.

All of your questions should be directed to the city of Omaha.

See this web site.

City of Omaha Planning Department - Permits and Inspections - Home (http://www.ci.omaha.ne.us/planning/permits/)

Click on the "What Agency do I pull a permit with" at the top center.

Thank you for your answer. I have talked to several people with the city sewer and plumbing departments. They are looking at this specific lot to determine what our obligation will be. There is some uncertainty because only a very small corner of the lot abuts with Calhoun road where the sewer lines are.