TDS Calculator
Calculate Total Dissolved Solids from electrical conductivity or water chemistry analysis
Calculate Total Dissolved Solids
Measured at 25°C with EC/TDS meter
Typical range: 0.5-0.8 (default: 0.67)
Calculation Methods
From Conductivity: TDS = k × EC (where k = 0.5-0.8, typically 0.67)
From Analysis: TDS = Sum of all anions + Sum of all cations
Units: mg/L = ppm for water (density ≈ 1 g/mL)
Temperature: EC measurements should be at 25°C for accuracy
Example Calculation
Well Water Analysis
Method: Electrical conductivity measurement
EC reading: 800 μS/cm at 25°C
Conversion factor: 0.67 (typical for natural waters)
Calculation
1. Apply formula: TDS = k × EC
2. Substitute values: TDS = 0.67 × 800 μS/cm
3. Calculate: TDS = 536 mg/L
4. Assessment: Good quality drinking water (300-600 mg/L range)
Result: 536 mg/L TDS - Good quality freshwater
Common Water Examples
Distilled Water
EC: 5 μS/cm, TDS: 3 mg/L
Rainwater
EC: 50 μS/cm, TDS: 34 mg/L
Tap Water (Good)
EC: 400 μS/cm, TDS: 268 mg/L
Well Water
EC: 800 μS/cm, TDS: 536 mg/L
Mineral Water
EC: 1200 μS/cm, TDS: 804 mg/L
Seawater
EC: 50000 μS/cm, TDS: 33500 mg/L
TDS Guidelines
TDS Tips
Measure EC at 25°C for accuracy
Calibrate meters regularly
k-factor varies with water composition
For water: mg/L = ppm
Higher TDS affects taste
Understanding Total Dissolved Solids (TDS)
What is TDS?
Total Dissolved Solids (TDS) refers to the combined content of all inorganic and organic substances dissolved in water. These include minerals, salts, metals, cations, and anions dissolved in a particular volume of water.
Common Sources
- •Natural mineral dissolution from rocks and soil
- •Agricultural runoff and fertilizers
- •Industrial and municipal wastewater
- •Salt water intrusion
- •Urban stormwater runoff
Measurement Methods
Electrical Conductivity
Quick and easy method using EC meters. Formula: TDS = k × EC
Gravimetric Analysis
Most accurate method involving water evaporation and residue weighing
Chemical Analysis
Detailed ion-by-ion analysis summing all dissolved components
Note: EC method is fastest but less accurate than gravimetric analysis.
Water Quality Standards
Drinking Water Classification
Excellent: < 300 mg/L
Low mineral content, very pure
Good: 300-600 mg/L
Acceptable for drinking
Fair: 600-900 mg/L
Still acceptable but high minerals
Poor: 900-1200 mg/L
Not recommended for drinking
Unacceptable: > 1200 mg/L
Unsafe for consumption
Water Type by Salinity
Regulatory Standards
- • WHO: 1,000 mg/L maximum for drinking water
- • EPA: 500 mg/L recommended, 1,000 mg/L maximum
- • EU: 1,500 mg/L maximum for drinking water
- • BIS (India): 500 mg/L desirable, 2,000 mg/L permissible