Water Treatment · Calculate & Specify

Coagulant and Polymer Dose Calculator

You have a dose from a jar test, an engineering calculation or an established site setpoint. This converts it into litres or kilograms of the product you actually buy, on the basis you actually buy it. It performs unit arithmetic on your numbers and nothing else.

THIS CALCULATOR DOES NOT DETERMINE THE CORRECT TREATMENT DOSE.

Enter a dose you have already validated. Acceptable sources of a validated dose:

· Jar testing on the actual water, at representative temperature and mixing energy
· Engineering validation or a process design calculation for the specific plant
· Manufacturer guidance for the specific grade in the specific duty
· Established, recorded site operating parameters

Your inputs

Nothing is assumed. Leave a field blank and the result says so.

Treated flowFlow unit

Validated dosemg/LFrom your jar test, engineering validation, manufacturer guidance or recorded site parameters.

That dose is expressed as

Jar-test doses are usually recorded as product as supplied. Check which basis your record actually used — the two differ by the active content.

Active contentoptional% w/wFrom the product TDS or CoA.Solution densityoptionalkg/LOnly for products dosed or priced by volume.

Dosing hours per dayhDays per monthd

Result

Arithmetic on your numbers only.

Flow: 250 m³/h
Product as supplied per day: 108 kg/day
Active substance per day: Not calculated
Product volume per day: Not calculated
Product per month: 3,240 kg/month

Active-substance quantity not calculated: no active content (% w/w) was supplied.
Product volume not calculated: no solution density (kg/L) was supplied. Density is product- and temperature-specific and is not assumed here.

This is a chemical quantity, not a treatment outcome. It does not predict turbidity removal, residual metal, sludge production or compliance of any kind.

Definitions, formulas and unit conversions

Validated dose (mg/L) — the concentration of chemical added per litre of water treated, established outside this tool. Active basis is the mass of the active substance itself; as-supplied basis is the mass of the formulated product including water and any other components.

Quantity	Formula
Mass rate	flow (m³/h) × dose (mg/L) ÷ 1000 = kg/h
Per day	kg/h × dosing hours per day
Active from as-supplied	kg as supplied × active % ÷ 100
As-supplied from active	kg active ÷ (active % ÷ 100)
Volume	kg as supplied ÷ density (kg/L) = litres
Polymer per dry tonne	t DS/day × kg active per t DS = kg active/day

Unit conversions used: 1 L/s = 3.6 m³/h · 1 m³/day = 1/24 m³/h · 1 US gpm = 0.2271247 m³/h · 1 US MGD = 157.7255 m³/h · 1 mg/L applied to 1 m³/h = 1 g/h.

Worked example

A plant treats 250 m³/h. Jar testing on the current raw water settled on 18 mg/L of PAC as supplied. The product TDS states a density of 1.20 kg/L. The dosing point runs 24 hours per day.

Mass rate as supplied = 250 m³/h × 18 mg/L ÷ 1000 = 4.5 kg/h.
Per day = 4.5 kg/h × 24 h = 108 kg/day.
Volume per day = 108 kg ÷ 1.20 kg/L = 90 L/day.
Per 30-day month = 2 700 L, or 3.24 tonnes as supplied.

The 18 mg/L came from a jar test on that water on that day. It is not a property of PAC, it is not transferable to another water, and this arithmetic does not validate it.

Reading the result

· The per-month figure is what belongs in an enquiry or a budget. State the basis you used, or the quotation you get back will not be comparable.
· If two products are being compared, compare the active requirement, not the as-supplied one. A cheaper product at half the active content is not cheaper.
· Deliveries vary. When the CoA active content of a delivery differs from the last one, the as-supplied dose has to be renormalised to keep the active dose constant.

Use this when

A jar test gave you a dose in mg/L and you need product volume per day for the feed pump and the purchase order.
You are comparing two coagulants whose active contents differ and want the as-supplied quantity for each.
You need a monthly tonnage to put into an enquiry or a budget.

How the output is produced

Active mass rate = flow x dose, converted to consistent units. 1 mg/L applied to 1 m³/h is 1 g/h of active.
As-supplied quantity divides the active requirement by the fractional active content you enter, and — for a solution quoted per litre — by the solution density you enter.
Nothing is assumed. If you do not supply an active content or a density, the calculator reports the active basis only and says so.

What this page does not determine

THIS CALCULATOR DOES NOT DETERMINE THE CORRECT TREATMENT DOSE. The dose must come from jar testing, engineering validation, manufacturer guidance or established site operating parameters.
It does not predict turbidity removal, residual metal, sludge production or any treated-water quality.
It does not establish potable-water suitability, regulatory compliance or discharge compliance.
It does not assume a density or an active content. Unknown inputs stay unknown.

Relevant Allzone products

These are catalogue identities relevant to this decision. A listing here is not a statement that the material is suitable for your system, and it is not a certification, performance or drinking-water claim.

Ask for a quotation or a specification

Where this comes from, and what it cannot tell you

Standard jar-test method literature (ASTM D2035 Standard Practice for Coagulation-Flocculation Jar Test of Water)
Supports: That the validated dose for a coagulant or polymer is determined experimentally on the actual water, at representative temperature and mixing energy, and expressed in mg/L.
Limitation: A jar test predicts direction and approximate optimum. Full-scale mixing, retention time and raw-water variability shift the result; confirmation on plant is required.
Standard practice — North America · Current standard practice; confirm the edition in force.
Water-treatment engineering references on coagulation and flocculation (AWWA Water Treatment Plant Design; MWH's Water Treatment: Principles and Design)
Supports: That coagulation performance is governed by charge neutralisation and sweep-floc mechanisms, that metal-salt coagulants consume alkalinity and depress pH, and that rapid-mix and flocculation energy and time control floc formation and strength.
Limitation: Design references describe mechanisms and typical ranges. They do not give a dose for a specific raw water; that comes from jar testing on the actual water.
Engineering literature — general practice · Established water-treatment engineering.
Product technical literature conventions across water-treatment chemical families (PAC basicity and Al2O3 content, hypochlorite trade percent vs percent available chlorine, alum Al2O3 basis, phosphonate active acid content, polymer active polymer content)
Supports: That the same chemical family is quoted on different bases by different suppliers, and that a price per kilogram is only comparable after normalising to active content and, for solutions, to solution density.
Limitation: Conventions vary by supplier and by region. The basis must be read from the specific TDS or CoA; it must never be assumed.
Manufacturer documentation — international · Always read the document for the specific product offered.
Polyacrylamide manufacturer technical literature on make-down, ageing and dosing of dry and emulsion polymers
Supports: That polymer solutions require controlled dilution and an ageing period to develop chain extension, that over-shearing degrades performance, and that emulsion and dry products are quoted on different active-polymer bases.
Limitation: Make-down times, concentrations and shear limits are grade-specific. Always work from the datasheet of the exact grade purchased.
Manufacturer documentation · Grade-specific; verify against the current TDS.