WaterCalcLabCalculators
Practical tools and clear methods for your next water decision.
Rainwater Harvesting Calculator
Estimate catchment yield from horizontal roof area and period rainfall. One millimetre on one square metre is one litre.
Open calculator ↗Rainwater harvestingRoof Rainwater Collection Calculator
Measure the horizontal roof footprint draining to the connected downpipes, not the sloping roof surface.
Open calculator ↗Water storageRainwater Tank Size Calculator
Size usable storage for a chosen rainless interval and compare annual supply with constant annual demand. Rainfall here must be annual.
Open calculator ↗Water storageRainwater Storage Duration Calculator
Divide usable storage by a constant daily demand to estimate rainless supply duration.
Open calculator ↗Rainwater harvestingRain Barrel Calculator
Estimate how many empty barrels could contain one specified rainfall event.
Open calculator ↗Costs & savingsRainwater Savings Calculator
Bound potential mains replacement by both available rainwater and eligible demand in the same period.
Open calculator ↗Garden irrigationGarden Water Requirement Calculator
Apply an ET?/Kc water balance for a garden hydrozone. ET? is a daily input, not calculated weather data.
Open calculator ↗Garden irrigationIrrigation Water Calculator
Convert a chosen net application depth into gross water volume with an explicit efficiency.
Open calculator ↗Garden irrigationDrip Irrigation Calculator
Calculate nominal zone flow and delivered volume from emitter count, measured emitter flow and runtime.
Open calculator ↗Garden irrigationSprinkler Runtime Calculator
Estimate runtime using the measured total flow of one zone and a chosen net dose.
Open calculator ↗Garden irrigationLawn Watering Calculator
Subtract effective rainfall from a locally chosen lawn dose before converting to volume.
Open calculator ↗Garden irrigationRaised Bed Water Calculator
Convert a selected water depth over the rectangular bed surface into a water volume.
Open calculator ↗Garden irrigationIrrigation Flow Rate Calculator
Use a timed bucket or meter measurement to calculate average flow.
Open calculator ↗Garden irrigationIrrigation Frequency Planner
Estimate root-zone depletion time using a simplified FAO-56 soil-water balance.
Open calculator ↗Water storageWater Tank Volume Calculator
Calculate exact geometry from internal dimensions for a vertical cylinder, box or sphere.
Open calculator ↗Water storageWater Tank Fill Time Calculator
Estimate refill time from current contents and a constant inlet flow.
Open calculator ↗Water storageWater Consumption Calculator
Scale a measured or selected per-person use over a period.
Open calculator ↗Water storageWater Pump Flow Calculator
Convert electrical power into a theoretical flow at specified total dynamic head and overall efficiency.
Open calculator ↗Costs & savingsWater Cost Calculator
Calculate a single volumetric tariff plus a fixed charge in the same billing period.
Open calculator ↗Costs & savingsRainwater ROI Calculator
Estimate simple annual payback using eligible annual demand and actually available annual supply.
Open calculator ↗Costs & savingsAnnual Water Savings Calculator
Calculate annual replacement potential for a specified number of active days. Enter annual usable supply.
Open calculator ↗Costs & savingsWater Usage Comparison Calculator
Compare two measured or modeled volumes for the same period, population and use case.
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