Tools and calculators

Convert between the five hardness units in common international use, with the resulting classification.

Calculate total hardness from measured calcium and magnesium concentrations, as laboratories report them.

Estimate total dissolved solids from an electrical conductivity reading — and see how wide the uncertainty really is.

Convert between pH and hydrogen ion concentration, and see what a given pH change actually means.

Convert between mg/l, µg/l, ng/l, ppm, ppb and ppt, and between nitrate reported as NO₃ and as N.

Convert between litres per second, cubic metres per day, megalitres per day and other flow units.

Convert between litres, cubic metres, megalitres, cubic kilometres, and imperial and US gallons.

Convert between Celsius, Fahrenheit and Kelvin, with the key water reference points marked.

Enter a set of test results and see how each compares with WHO, EU, UK and US reference values, with the interpretation for each.

Estimate your household’s daily water use from how you actually use it, and see which change would matter most.

Work out what a shower actually uses, what it costs, and how much energy goes into heating it.

Which uses less water depends entirely on how long the shower is — this finds your crossover point.

Estimate annual water use and cost from toilet flushing, and what a modern cistern would save.

How much water a dripping tap or running toilet wastes over a year, and what it costs.

Estimate a metered water and sewerage bill from consumption, and compare it with an unmetered charge.

Compare an estimated metered bill against your current unmetered charge.

The cost multiple between mains water and bottled, for your own consumption and prices.

Convert a rainfall depth over an area into a volume — the calculation behind every catchment yield estimate.

Estimate annual yield from a roof and size a storage tank against your intended use.

Size a storage tank from daily demand and the number of days of autonomy you want.

Estimate the volume of a reservoir, pond or tank from its dimensions.

Estimate how much water a reservoir or pond loses to evaporation over a season.

Volume of water held in a length of pipe — needed for flushing, disinfection and dead-leg assessment.

Calculate recovery ratio, concentrate flow, concentration factor and salt rejection for an RO system.

Size a softener from hardness and water use, and see how much sodium it adds.

Match a water problem to the treatment technologies that actually address it — and see which do not.

Estimate energy demand and energy cost for a desalination plant of a given capacity.

Estimate crop irrigation need from reference evapotranspiration, crop coefficient, rainfall and system efficiency.

Compare the water footprint of foods and products, with the green, blue and grey components separated.

Calculate renewable freshwater per person for any resource volume and population, and see which scarcity band it falls in.