Reagents and solvents used for polymer synthesis are reused or recycled rather than discarded. The outflow from each step of polymer synthesis may be collected separately in one of multiple dedicated containers. Reuse returns the outflow from a step of polymer synthesis back to an input of a polymer synthesizer for subsequent use in that same step. Recycling processes the outflow from one or more steps of polymer synthesis to restore original concentrations or purity levels for use in a later synthesis run. Quality control analysis may determine if outflow collected from a polymer synthesizer is reused or recycled. These techniques reduce reagent cost and waste quantity. These techniques may be used with phosphoramidite or enzyme-based synthesis of deoxyribonucleic acid (DNA).