TDS Calculator with Ion Analysis

Advanced water quality analysis with ion composition calculation, temperature compensation, and comprehensive water quality assessment.

TDS Formula: TDS (ppm) = Conductivity (µS/cm) × Conversion Factor (typically 0.5-0.7)

Electrical conductivity in microsiemens per centimeter
Factor depends on dissolved solids composition
342 ppm Calibration
Soft Tap Water
Mineral Water
Hard Water
Seawater

Advanced TDS Formula: TDS = Conductivity × Factor × Temperature Compensation

Temperature compensation uses the standard coefficient of 2% per °C from reference temperature (usually 25°C)

Measurement temperature
Typically 0.5-0.7
Temperature at which conductivity is referenced
Rate of change per degree Celsius

Ion Composition Analysis: Calculate TDS from individual ion concentrations and check ionic balance

Enter values for each ion in any unit (mg/L, mmol/L, or ppm). The calculator will convert all values and check the ionic balance.

Ion Concentration Input

Enter values for each ion. The calculator will automatically convert between units.

Value Unit Ion Weight Charge mmol/L mg/L meq
Tap Water
Mineral Water
Hard Water
Seawater
Hydroponic Solution
Calculating...

Additional Features

TDS Meter Calibration

Calibrate your TDS meter using standard calibration solutions

Measurement History

342 ppm
Calibration Solution
684 µS/cm × 0.5
96 ppm
Tap Water
150 µS/cm × 0.64

Understanding Total Dissolved Solids (TDS)

Total Dissolved Solids (TDS) refers to the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water. TDS is expressed in units of mg per unit volume of water (mg/L) or as parts per million (ppm).

Primary Components of TDS:

  • Calcium and Magnesium: Contribute to water hardness
  • Sodium and Potassium: Common in all water sources
  • Bicarbonates and Carbonates: Affect pH and alkalinity
  • Chlorides and Sulfates: Often from geological sources
  • Silica and Nitrates: Can indicate pollution or geological origin

TDS Water Quality Guidelines

TDS Level (ppm) Water Quality Rating Description Common Uses
0-50 Excellent Very pure water, minimal minerals Laboratory work, sensitive equipment
50-250 Good Low mineral content, ideal for drinking Drinking, cooking, aquariums
250-500 Fair Moderate mineral content, acceptable for most uses General household use, gardening
500-900 Poor High mineral content, may affect taste Limited drinking, irrigation
900-1200 Unacceptable Very high mineral content, not recommended for drinking Industrial use only
1200+ Unacceptable Excessive minerals, may be harmful Not recommended for any use

TDS in Different Water Sources

1

Distilled/Deionized Water: 0-10 ppm. Water with almost all minerals removed through distillation or deionization processes.

2

Rainwater: 10-30 ppm. Naturally soft water with low mineral content, but can pick up contaminants from atmosphere.

3

Municipal Tap Water: 50-400 ppm. Varies greatly by location and water source. Generally safe for drinking within this range.

4

Well Water: 100-600 ppm. Can vary significantly based on local geology. May require testing and treatment.

5

Mineral Water: 200-500 ppm. Naturally contains higher mineral content, often with specific health claims.

6

Seawater: 30,000-40,000 ppm. Extremely high TDS due to high salt concentration. Not suitable for drinking without desalination.

Applications of TDS Measurement

  • Drinking Water Quality: Monitoring safety and taste of drinking water
  • Aquaculture and Aquariums: Maintaining optimal conditions for fish and aquatic life
  • Hydroponics: Controlling nutrient solutions for plant growth
  • Swimming Pools: Balancing water chemistry for safety and comfort
  • Industrial Processes: Monitoring water purity for manufacturing and cooling systems
  • Environmental Monitoring: Assessing water pollution and ecosystem health

Calculator Features:

  • Three calculation modes: Basic, Advanced (with temperature compensation), and Ion Composition Analysis
  • Pre-configured conversion factors for different water types
  • Temperature compensation based on standard 2% per °C coefficient
  • Water quality rating based on EPA and WHO guidelines
  • Ion composition analysis with 16 common ions
  • Ionic balance check for data validation
  • Visual comparison with common water sources
  • Interactive chart showing TDS-conductivity relationship

Frequently Asked Questions

Conductivity measures water's ability to conduct electrical current, which increases with more dissolved ions. TDS is the actual concentration of dissolved solids. They are related through a conversion factor (typically 0.5-0.7), but this factor varies based on the specific ions present. Conductivity is measured directly with a meter, while TDS is often calculated from conductivity.

According to the EPA, secondary drinking water regulations recommend TDS levels below 500 ppm for palatability. The WHO suggests that water with TDS below 300 ppm is generally considered good for drinking, while levels between 300-600 ppm are acceptable. Water with TDS above 1000 ppm is not recommended for regular consumption. However, extremely low TDS (below 50 ppm) may also be undesirable as it lacks beneficial minerals.

Conductivity increases with temperature because ions move faster in warmer water. Without temperature compensation, the same water would show different conductivity (and thus different calculated TDS) at different temperatures. Standard practice is to compensate all readings to a reference temperature (usually 25°C) using a temperature coefficient, typically 2% per °C. This allows for accurate comparisons between measurements taken at different temperatures.

The conversion factor depends on the type of dissolved solids in your water:
  • 0.5: For pure water or water with mainly NaCl (sodium chloride)
  • 0.55-0.6: For distilled or deionized water with minimal ions
  • 0.64: Standard for typical drinking water with mixed ions
  • 0.67-0.7: For hard water with high calcium/magnesium content
  • 0.75: For seawater or water with high sulfate content
When in doubt, use 0.64 as it's the most common factor for general purpose water analysis.

TDS measurement can indicate general water quality but cannot identify specific contaminants. A sudden increase in TDS may signal contamination, but it could also be from harmless mineral sources. TDS meters are useful for monitoring changes in water quality over time and for applications where specific mineral content is important (like hydroponics or aquariums). For detecting specific contaminants like heavy metals, pesticides, or bacteria, specialized testing is required.