How much water is wasted waiting for hot water?
Estimate hot-water waiting waste and water/sewer cost from measurements or pipe dimensions.
Estimate hot-water waiting waste and water/sewer cost from measurements or pipe dimensions.
Prefer measured waiting time. Pipe mode estimates stagnant-water replacement only; excludes heater ignition, mixer internals, actual bends, temperature arrival and pipe heat loss. Costs cover entered volumetric rates, excluding fixed/tiered charges and heating energy.
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Method
Waste per event = L/min × s ÷ 60
Pipe water volume = π × (mm ÷ 1000 ÷ 2)² × m × 1000; Estimated replacement time = L ÷ (L/min) × 60
Daily average water (L) = Waste per event × Hot-water draws per day; Annual wait (h) = s × Hot-water draws per day × 365 ÷ 3600
1 US gal = 3.785411784 L; 1 mL = 0.001 L
Annual water (L) = Daily average water (L) × 365; Monthly average water (L) = Annual water (L) ÷ 12
Annual cost = Annual water (L) ÷ 1000 × (Water rate + Sewer rate (optional)); Monthly average cost = Annual cost ÷ 12
Notes
Prefer measured waiting time. Pipe mode estimates stagnant-water replacement only; excludes heater ignition, mixer internals, actual bends, temperature arrival and pipe heat loss. Costs cover entered volumetric rates, excluding fixed/tiered charges and heating energy.