Water treatment calculations

Practical calculators for RO, softeners, flow, and tank checks

Quick reference tools for engineers, contractors, site teams, and water treatment companies. Results are guide calculations and should be checked against equipment manuals, site conditions, and project specifications.

RO Recovery

Enter any two flows to calculate the third, recovery percentage, and permeate/reject ratio.

Feed flow Permeate flow Reject flow Recovery: -

Recovery % = permeate / feed x 100. Feed = permeate + reject.

RO Salt Rejection

Feed conductivity Permeate conductivity Salt rejection: -

Salt rejection % = (1 - permeate conductivity / feed conductivity) x 100.

Softener Capacity

Resin volume, litres Exchange capacity, grams CaCO3 per litre resin Raw water hardness, ppm as CaCO3 Estimated throughput before regeneration: -

Throughput m3 = resin litres x exchange capacity / hardness. Hardness in ppm as CaCO3 is equivalent to grams per m3. The default 60 g/L is a rough estimate only.

Hardness Conversion

Hardness, ppm as CaCO3 Clark: - | dH: - | fH: -

Flow Conversion

Flow, m3/hr L/min: - | L/sec: -

Tank Volume

Length Width Height Water volume: -

Enter the tank length, width, and height in metres to estimate the water volume in litres.