Schoeller Diagram Plotter
Plot semi-logarithmic Schoeller profiles to compare many water samples across all major ions at once, keeping absolute concentrations visible.
What a Schoeller diagram shows
A Schoeller diagram puts the major ions along the horizontal axis — typically Ca, Mg, Na+K, Cl, SO₄ and HCO₃ — and concentration in milliequivalents per litre on a logarithmic vertical axis. Each water sample becomes one line connecting its values across the ions.
The logarithmic axis is the whole point. It lets a dilute mountain spring and a brine appear on the same figure without one being flattened against the baseline, and it makes ratios readable as vertical distances: two samples separated by the same gap at every ion differ by a constant factor, whatever their absolute concentrations.
Data
Paste straight from Excel or Google Sheets — include the header row and the columns are matched by name, in any order.
| # | Sample(opt) | Group(opt) | Camg/L | Mgmg/L | Namg/L | Kmg/L(opt) | Clmg/L | SO4mg/L | HCO3mg/L | CO3mg/L(opt) | TDSmg/L(opt) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | ||||||||||||
| 2 | ||||||||||||
| 3 | ||||||||||||
| 4 |
0 rows of data
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Export Piper + Stiff + Schoeller
Renders all three hydrochemical diagrams from the table above and downloads them as one zip.
Options
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How to read it
Compare the shapes of the lines, not their heights. Two parallel lines mean two waters with identical ionic ratios at different total concentrations — the signature of simple dilution by recharge or concentration by evaporation, with no reaction involved. Lines that cross mean genuinely different chemistry: something has added or removed a specific ion, and the ion where the crossing happens tells you which one.
A downward kink at sulphate against an otherwise similar profile points to sulphate reduction. A sample sitting high on sodium and low on calcium relative to its neighbours suggests cation exchange. Because every ion stays visible, the Schoeller diagram is the most direct of the three standard hydrochemical plots for spotting a single anomalous constituent.
Strengths and limits
It handles far more samples legibly than a Stiff diagram, keeps absolute values that a Piper diagram discards, and extends easily to minor ions such as nitrate or fluoride. Its weakness is that the order of ions along the axis is arbitrary and changes which crossings are visually obvious — so keep the order consistent across a study, and state it in the caption.
Common questions
- Piper, Stiff or Schoeller?
- Piper to classify water types and identify mixing. Stiff to show one sample as a map-postable fingerprint. Schoeller to compare many samples ion by ion while keeping absolute concentrations.
- Can I plot minor ions too?
- Yes — the logarithmic axis is what makes it possible to show nitrate at 0.5 meq/L on the same figure as bicarbonate at 8 meq/L without either becoming unreadable.