Data Sources & References

About The Harmony Index™

The Harmony Index™ is a proprietary mineral-balance framework developed by Leste's research team. It moves beyond simple compliance — asking not just whether water passes a test, but whether its minerals work together in balance.

Why It Matters

Most water comparisons look at individual minerals in isolation: "This water has 50 mg/L of calcium." But minerals interact. Too much calcium without enough magnesium creates a structural imbalance. Too much sodium relative to total dissolved solids changes taste and mouthfeel. High nitrate, even below the legal limit, indicates source vulnerability.

The Harmony Index™ measures eight ratios and relationships that define balanced mineral water — the same eight indicators used in Leste's scientific benchmarking thesis.

The Eight Indicators

• Ca:Mg Ratio (1.7–4.5 optimal) — Calcium and magnesium are the two structural minerals. This ratio determines how well the body can absorb and utilise both. Outside 1.0–8.0, the balance is compromised.
• TDS Band (100–300 mg/L optimal) — Total dissolved solids defines mineral density. Too low (<50) is nearly distilled. Too high (>500) tastes heavy and metallic.
• pH Band (6.8–8.0 optimal) — Natural mineral water should sit near neutral. Below 6.5 risks acidity; above 8.5 tastes chalky or soapy.
• Nitrate Band (<1.0 mg/L optimal) — Nitrate is a purity indicator, not a mineral. Lower is always better — it reflects how protected the source is from agricultural or industrial runoff.
• (Ca+Mg):TDS Ratio (0.12–0.35 optimal) — Measures whether the structural minerals (calcium + magnesium) make up a healthy share of total mineral content. Too low means the water is dominated by sodium or sulfate. Too high means it's essentially a calcium supplement.
• Na:TDS Ratio (<0.10 optimal) — Sodium should be a minor contributor. Above 0.30, the water starts tasting salty and becomes unsuitable for low-sodium diets.
• Bicarbonate Band (50–250 mg/L optimal) — Bicarbonate buffers pH naturally. Too low (<20) means weak buffering. Too high (>400) creates a chalky, alkaline taste.
• Sodium Band (<50 mg/L optimal) — Direct sodium measurement. Below 50 mg/L is heart-friendly. Above 200 mg/L is the EU maximum for natural mineral water.

The Three Bands

Each indicator is scored against three bands — not a pass/fail binary:

• Gold — Optimal — The target zone where minerals are in true harmony. This is where Leste sits on every indicator.
• Green — Pass — Acceptable but not ideal. Water in this band is compliant and safe, but lacks the balance that defines premium mineral water.
• Gray — Outside Range — Falls outside acceptable parameters. May still be legally compliant, but the mineral relationship is compromised.

Why Leste Created This

Existing water quality frameworks (WHO, EU Directive 2009/54/EC) set maximum limits — what water must not exceed to be safe. They don't measure balance — what makes water exceptional.

The Harmony Index™ fills that gap. It was built from Leste's own scientific benchmarking thesis, using the same 12-indicator, 100-point analytical model that underpins our Intertek-certified lab reports. Every competitor in our comparison is scored using this exact framework — no exceptions, no adjustments.

Methodology

All competitor data in the Leste Water comparison meets the following criteria:

• Still water only — No naturally or artificially carbonated waters. Carbonation alters pH and mineral perception.
• Complete dataset — All 11 parameters must be published in a single verifiable source: TDS, pH, Calcium (Ca), Magnesium (Mg), Sodium (Na), Potassium (K), Silica (SiO₂), Sulfate (SO₄), Chloride (Cl), Bicarbonate (HCO₃), and Nitrate (NO₃).
• Natural mineral water — All brands are certified natural mineral water under their respective national or EU frameworks. No purified, distilled, or treated waters.
• Published source — Data is sourced from official brand websites, published geological surveys, or FineWaters.com, the authoritative database for premium bottled mineral waters.

Note on generic naming: The public-facing comparison table on /science uses generic descriptive names rather than trademarked brand names. This maintains neutrality and focuses on water composition rather than brand identity. Competitor brand names are not disclosed on this page — each profile is linked to its original published source for independent verification.

Published Scientific Studies

Mineral composition and health implications referenced across this site are based on published scientific literature and independent laboratory analysis. Leste Water does not make unverified medical claims. The following studies inform our understanding of mineral water composition, infant safety, and geological filtration.