Hydrochart is a free, browser-based Chadha diagram maker. It plots the difference in alkaline versus alkali ions against the difference in weak-acid versus strong-acid anions, placing each sample in one of eight process fields. Everything runs locally; your data never leaves your device.
Make a Chadha diagram in three steps
Load your data
Open the plotter and drop in a CSV or Excel file of major-ion concentrations, or paste a table. Column headers are matched automatically.
Get the diagram
Hydrochart computes the two Chadha differences for every sample and plots them, so each point lands in the process field it belongs to.
Export it
Download the finished diagram as vector SVG or PNG — sharp at any size, ready for a report, thesis or paper.
What a Chadha diagram shows
A Chadha diagram is a rectangular plot with two axes derived from ion percentages in milliequivalents: the x-axis is (Ca+Mg) minus (Na+K) and the y-axis is (CO₃+HCO₃) minus (SO₄+Cl). The four quadrants and their sub-fields tie directly to processes — recharging Ca–HCO₃ water, base-ion exchange, reverse exchange, and seawater/end-member mixing — which makes it a compact way to read what is driving a sample's chemistry.
What data do I need?
Supply your major ions in mg/L and Hydrochart converts to milliequivalents and does the rest:
| Group | Ions |
|---|---|
| Cations | Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K) |
| Anions | Bicarbonate (HCO₃) and Carbonate (CO₃), Sulfate (SO₄), Chloride (Cl) |
| Optional | TDS, pH and EC — used for labelling and QA, estimated when absent |
Not sure of the layout? Download the CSV template and paste your values into it.
Why use Hydrochart
- Genuinely free. Create and view unlimited Chadha diagrams with no account. Free exports carry a small watermark; Pro (USD $29/year) removes it and adds CSV export.
- Nothing is uploaded. The whole tool runs client-side in your browser, so confidential monitoring data stays on your machine.
- Publication-ready output. Vector SVG and PNG export, with drag-to-place sample labels and leader lines for clean figures.
- One dataset, every diagram. The same file also plots Piper, Stiff, Schoeller, Chadha, Durov and Gibbs — no re-entry.
- Built-in quality control. Every analysis gets a cation–anion charge-balance error, flagged when it exceeds ±5%.
New to Chadha diagrams?
If you want the theory before you plot, read the companion guide: the Chadha diagram explained. It covers what the plot shows and how to interpret where your samples fall.