If you are in possession of a septic system you substantially lower the quantity of waste water your system has to manage daily.
Both systems are a breeze to install and both have code approvals. The system is wholly off-grid which means it does not want power from any external source. There’s an immediate water system and storage water system.
Make sure there’s an accessible outlet close to the water heater. Many tankless water heaters include a lifetime guarantee. Oh and I almost forgot to inform you that tankless immediate water heaters are made from recyclable materials, not you will want to recycle any time soon.