Breakeven costs for distributed advanced technology water-treatment systems

Breakeven costs associated with the strategic distribution of advanced treatment units in a water supply network to manage network-derived water quality degradation were investigated. Disinfections by-product (DBP) formation was used as a representative water quality degradation parameter. A basic DBP formation model was used to predict that fraction of residential service population receiving water degraded below required quality levels within a hypothetical water utility service population. The costs of upgrading centralized treatment facilities to meet DBP water quality standards were estimated and then apportioned over that population fraction to estimate breakeven or equivalent cost allowances for an alternative distributed treatment approach. Breakeven costs for single-connection treatment units were calculated for a range of service populations. A sensitivity analysis of the impacts of various network parameters on breakeven costs revealed the existence of singularities—sudden shifts in optimal technology selection—resulting from relatively small variations in required treatment levels.