Abstract: Improvements in methods of and apparatus for recarbonation of lime-treated water with an oil fired submerged combustion burner; establishing a smaller reservoir adjacent a larger primary recarbonation reservoir with the oil fired burner in the former, passing the combustion products out of the smaller reservoir water into the primary reservoir water to recarbonate the latter, flowing water through the smaller reservoir in quantities to cool the burner and remain below boiling point, and passing the smaller reservoir water to one of:1. waste or a sewer; or2. the larger reservoir; or3. part to each of (1) and (2);Apparatus for carrying out such improved recarbonation process.