But yes, unless you spend serious money (own sewer, water from underground etc), it's basically solution for "the power pole is down", not any grid wide problems.
It is often the case (at least where I live) that having a septic system and well is far more economical than obtaining a property with access to city utilities.
You'd be better off with an air sourced hear pump for hot water anyway - the one in my house uses less power then my dehumidifier.