AWP Labs · Chemistry

Water analysis worksheet

Enter cations and anions from a water analysis. The worksheet converts to meq/L, checks the ion balance and totals hardness, alkalinity and TDS.

Lab results

Cations

Calcium Ca²⁺

mg/L

Magnesium Mg²⁺

mg/L

Sodium Na⁺

mg/L

Potassium K⁺

mg/L

Barium Ba²⁺

mg/L

Strontium Sr²⁺

mg/L

Iron Fe²⁺

mg/L

Manganese Mn²⁺

mg/L

Aluminum Al³⁺

mg/L

Anions

Bicarbonate HCO₃⁻

mg/L

Carbonate CO₃²⁻

mg/L

Sulfate SO₄²⁻

mg/L

Chloride Cl⁻

mg/L

Fluoride F⁻

mg/L

Nitrate NO₃⁻

mg/L

Phosphate PO₄³⁻

mg/L

Other

Silica SiO₂

mg/L

Temperature

°C

Conductivity (optional)

µS/cm

Leave at 0 to skip the check.

Only dissolved ions are of interest, for example dissolved iron and dissolved silica.
pH is best measured at the site, because it can change in a sample bottle.
Include SDI if it is available from the site. Labs do not run SDI.

Results

Ion balance

-1.0%

Within ±5%. The analysis is internally consistent.

−20% anions high0cations high +20%

Cations30.93 meq/L

Anions31.53 meq/L

Sodium Calcium Magnesium Potassium Chloride Sulfate Bicarbonate Nitrate

TDS by sum of ions: 2,034mg/L
Total hardness: 485mg/L as CaCO₃; Very hard · 28.3 grains/gal
Alkalinity: 230mg/L as CaCO₃
Calcium hardness: 300mg/L as CaCO₃

Send to an engineer

Check this water for scaling

How this is calculated

Milliequivalents. Each ion is converted with meq/L = mg/L ÷ equivalent weight, where equivalent weight is molar mass divided by charge.

Ion balance. Water is electrically neutral, so cations and anions should match: Balance % = (Σ cations − Σ anions) ÷ (Σ cations + Σ anions) × 100.

Hardness and alkalinity. Hardness = 2.497 × Ca + 4.118 × Mg and Alkalinity = 0.8202 × HCO₃ + 1.6661 × CO₃, both in mg/L as CaCO₃. Above pH 8.3 carbonate is significant, and leaving it out makes alkalinity read low.

Conductivity check. If you enter conductivity, TDS by sum ÷ Conductivity (µS/cm) should fall between 0.55 and 0.75. A ratio outside that range points to a bad result or a bad conductivity reading, which the ion balance alone can miss.

Assumptions

All concentrations are entered in mg/L as the ion.
Iron and manganese are treated as divalent (Fe²⁺, Mn²⁺) and phosphate as PO₄³⁻.
An ion balance within ±5% is the usual acceptance limit for a routine analysis.
TDS by sum counts bicarbonate in full, as membrane projections do.

A preliminary estimate for planning. AWP confirms every figure against your water, site and permit before quoting.

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