Water Treatment Calculators
Process calculation tools for clarification, media filtration, chemical dosing, ion exchange, and softening.
Plant Mass Balance
Assemble the whole plant as an ordered chain of unit operations: raw intake to product and waste, stage-to-stage product flow, external make-up, derived concentrate TDS by salt conservation, and plant-wide water and salt balance checks.
product = feed × recovery/100 · waste = feed − product · Cw = (Qf·Cf − Qp·Cp)/Qw · intake + make-up = plant product + plant waste Water Analysis & Treatment Selection
Enter a feedwater analysis once: derive hardness, cation–anion charge balance, TDS by summation, ionic strength and saturation indices (LSI/RSI), then compare water-quality drivers against the treatment surfaces already built on the platform — a qualitative start, not a diagnosis.
hardness = 2.497·Ca + 4.118·Mg · balance% = 200·(Σmeq+ − Σmeq−)/(Σmeq+ + Σmeq−) · LSI/RSI via existing saturation engine Filter Sizing Calculator
Size a conventional rapid-gravity multimedia filter from design flow, filtration rate, bed depth and media effective size: required filter area, design area after the engineer's safety factor, and media volume. The unit count needs a stated catalogue unit area, and no clean-water head loss is invented.
A = Q/v · design area = A × safety factor · units = ceil(design area / unit area) only when a catalogue unit area is supplied · media volume = design area × depth · no head loss is computed Cartridge Filter Sizing Calculator
Size cartridge and bag filter elements and housings from design flow, feed solids and the manufacturer's element flow rating: hourly solids load, element count and housing count. No element size is assumed and no differential pressure is invented.
solids load (g/h) = Q × feed solids · elements = ceil(Q / element flow rating) × safety factor · housings = ceil(elements / elements per housing) · no differential pressure is computed Disinfection CT Value Calculator
Compute the achieved CT value from residual disinfectant concentration and contact time, compare it against a required CT you state from your disinfection reference, and get the contact time the design needs to reach it.
CT = residual concentration × contact time · margin = (achieved − required) / required · contact time needed = required CT / residual · no required CT and no UV dose are built in Ultrafiltration (UF) Membrane Engineering
Size UF membrane area from permeate flow and design flux, compute transmembrane pressure from the feed/filtrate/concentrate pressures, and read normalised flux against the reference condition to expose fouling.
A = Qp/flux · TMP = Pf − (Pfilt + Pc)/2 · normalised flux against reference temperature Nanofiltration (NF) Membrane Engineering
Close the NF water and solute balance from a stated recovery and rejection to get permeate and concentrate flow and TDS, then size membrane area from the permeate flux.
Qp = Qf·Y · Qc = Qf − Qp · solute balance Qf·Cf = Qp·Cp + Qc·Cc · A = Qp/flux Ion Exchange (IX / IER) Bed Sizing
Size an ion exchange bed from service flow, resin volume and empty-bed contact time, and compute stoichiometric regenerant demand from the ionic loading.
V = Q·EBCT · service flow = Q/A · regenerant mass from stoichiometric ionic loading Sodium Metabisulphite Dosing Calculator
Dose sodium metabisulphite from the chlorine residual it must neutralise or the sulphite level it must hold, using the stoichiometric ratio and your product strength. No chlorine residual and no product strength are assumed.
SMBS = Cl₂ demand × 190.12/70.90 (1 mol each), or sulphite target ÷ 2 (1 mol SMBS yields 2 mol SO₃²⁻) · product mass = active ÷ the certificate assay when one is given, else ÷ nominal strength — the assay replaces the strength, never both · no finished pH is predicted Coagulant Dosing Calculator
Turn a jar-test coagulant dose into active metal and product mass per day, from the dose basis you measured and the product active content. The dose is your jar test and the pH outcome is not predicted.
active metal (kg/h) = Q × dose ÷ 1000 · product (kg/day) = active ÷ active content · safety factor applies to both so they cannot disagree · no pH is predicted Clarifier Sizing Calculator
Size a circular or rectangular clarifier from the surface overflow rate, then check it against the solids loading when you state both. Reports which criterion governs and never predicts a solids removal.
area = Q ÷ SOR · load-based area = (Q × 24 × SS × removal%) ÷ (1000 × capacity) · governing criterion is reported · detention time is a consequence, not a criterion Activated Sludge Sizing Calculator
Size an aeration basin from the applied COD load, the F/M loading and the MLVSS, then audit your stated SRT, HRT and volume against each other. Reports oxygen demand as demand only, never as air flow.
load = Q × S₀ ÷ 1000 · V = load ÷ (F/M × X) on the APPLIED load · Px = Yobs × load removed · θc = VX ÷ Px · wasting = inventory ÷ θc · O₂ = 8/7 × COD removed, +4.57 per kg NH₄-N removed · air flow is not calculated GAC Contactor Sizing Calculator
Size a granular activated carbon bed from the empty bed contact time you selected, giving the bed volume, media mass and backwash shell volume. Breakthrough and contaminant removal are not predicted.
bed volume = Q × EBCT ÷ 60 · media mass = bed volume × bulk density · backwash shell = bed volume × (1 + expansion) · breakthrough and removal are NOT predicted UV Disinfection Sizing Calculator
Size a UV reactor bank from the required dose and design flow, then count parallel reactors against the out-of-service allowance. The ideal power is stated separately from the validated reactor power.
required power = Q × dose (1 mJ/cm² over 1 m³/h is 1 W) · reactors = ceil(required ÷ (module power × duty factor)) · annual energy is nameplate × availability CIP Tank Sizing Calculator
Size CIP cleaning and storage tanks from your cleaning protocol volume per element and the heel the tank retains, with separate alkaline, acid and neutral volumes and optional annual chemical consumption.
cleaning volume = elements × protocol volume per element · tank volume = cleaning volume ÷ (1 − heel) because the heel is retained · annual chemical = mass × cleanings per year Brine Volume and Mass Calculator
Annualise the brine volume and salt mass from the concentrate stream, with optional disposal cost and the dilution arithmetic against a stated permit limit. No compliance verdict is issued.
annual volume = brine flow × operating hours · salt mass = TDS × volume ÷ 1e6 to tonnes · dilution = Q × (C − limit) ÷ limit · no compliance verdict is issued