I believe duplication is allowed in this Plumbing Wood category and I have now installed a second septic tank and a second drain field. In this case, both were replacements of existing failed systems, and they are two separate systems (replaced the tank at the rental and replaced the drain field at the south restroom). The failed septic tank was a 400 gallon single compartment corrugated steel tank that had rusted through and was acting more like a drain field than a septic tank. I replaced it with a 1250 gallon two compartment concrete tank that was less than one year old that I recovered from a demolition site and hired the original manufacturer to move for me. The drain field was a replacement for an existing drain field that either I couldn't find or never really existed. A new 1000 gallon two compartment septic tank had already been placed by the previous owner, but never backfilled or hooked up, so I installed a new drain field and hooked it up to the tank and connected the new tank to the building.