TDS Calculator

Category: Chemistry
- April 04, 2025
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Calculate Total Dissolved Solids (TDS) in water samples. This calculator helps determine water quality and solute concentration based on electrical conductivity measurements.

Calculation Method

Conductivity Measurement

Typically between 0.55-0.8 depending on water type

Output Settings

Advanced Options

About Total Dissolved Solids (TDS)

Total Dissolved Solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid. The solids must be small enough to survive filtration through a sieve size of two micrometers.

TDS Measurement Methods
  • Conductivity Method: Based on the electrical conductivity of water. As dissolved solids increase, electrical conductivity increases.
  • Gravimetric Method (Evaporation): A water sample is filtered, evaporated, and the remaining residue is weighed.
  • Sum of Ions Method: Adding up the concentrations of individually measured ions.
Water Classification by TDS
  • Fresh water: Less than 1,000 mg/L
  • Brackish water: 1,000 to 10,000 mg/L
  • Saline water: 10,000 to 35,000 mg/L
  • Hypersaline water: More than 35,000 mg/L
Common TDS Sources
  • Natural Sources: Minerals from rocks and soils, decaying organic matter
  • Human Activities: Urban runoff, industrial wastewater, sewage, agricultural chemicals
  • Water Treatment Chemicals: Additives like chlorine, fluoride, or water softening compounds
Importance of TDS Monitoring
  • Drinking Water Quality: High TDS may indicate pollution or health risks
  • Agricultural Use: Irrigation water with high TDS can damage crops and soil
  • Industrial Applications: High TDS water can cause scaling in boilers and cooling towers
  • Aquatic Ecosystems: Changes in TDS can affect aquatic organisms
  • Water Treatment: TDS levels help determine appropriate treatment methods
Standards and Guidelines
  • WHO Guidelines: No specific health-based guideline value, but levels above 1000 mg/L may be objectionable to consumers
  • US EPA Secondary Standard: 500 mg/L (recommended, not enforced)
  • EU Drinking Water Directive: No specific parameter for TDS

What Is the TDS Calculator?

The TDS Calculator is an interactive tool used to estimate the Total Dissolved Solids (TDS) in a water sample. TDS refers to the total amount of all inorganic and organic substances dissolved in water. Measuring TDS is crucial for understanding water quality for uses like drinking, agriculture, aquariums, and industrial applications.

Why TDS Matters

TDS levels can affect taste, suitability for irrigation, industrial processes, and the health of aquatic life. This calculator helps users determine if their water is classified as fresh, brackish, saline, or hypersaline, based on the concentration of dissolved solids.

  • Fresh water: Below 1,000 mg/L
  • Brackish water: 1,000–10,000 mg/L
  • Saline water: 10,000–35,000 mg/L
  • Hypersaline water: Above 35,000 mg/L

Formulas Used

Conductivity Method:
TDS (mg/L) = Conductivity (µS/cm) × Conversion Factor

Evaporation Method:
TDS (mg/L) = (Final Weight − Initial Weight) × 1000 / Volume (L)

Sum of Ions Method:
TDS (mg/L) = Σ (Concentration of all measured ions)

How to Use the TDS Calculator

This calculator provides three methods to estimate TDS. Choose the method that best fits the data you have:

1. From Conductivity

Use this if you have a conductivity meter:

  • Enter the measured conductivity value.
  • Adjust the conversion factor (usually between 0.55–0.8 depending on the water source).
  • Include the water temperature for better accuracy.

2. From Individual Ions

Use this if you have lab results with ion concentrations:

  • Enter values for common ions like calcium, sodium, and chloride.
  • Add any other measured ions using the "+ Add Additional Ion" option.

3. From Evaporation

Use this if you have recorded the mass before and after evaporating a water sample:

  • Input the initial and final weights of the container.
  • Enter the volume of the sample.

Output Settings

Select your preferred TDS unit (mg/L, ppm, or g/L) and the number of decimal places. You can also enable options to display a detailed breakdown and a pie chart of the TDS composition.

Benefits of Using This Calculator

  • Quick Assessment: Quickly evaluates water quality.
  • Flexible Inputs: Choose the method based on the type of data you have.
  • Helpful for Multiple Fields: Useful in agriculture, aquaculture, laboratories, and water treatment.
  • Visual Insights: Pie charts and breakdown tables help visualise the composition of dissolved solids.

Frequently Asked Questions (FAQ)

What is a safe TDS level for drinking water?

Generally, a TDS level below 500 mg/L is considered acceptable for drinking by many health and environmental agencies. However, taste and local standards may differ.

What does a high TDS level mean?

High TDS levels may suggest pollution, excessive minerals, or contamination from sewage or industrial runoff. It's important to check the source if levels are unusually high.

What is the typical conversion factor for conductivity?

It ranges from 0.55 to 0.8 depending on the type of water. Natural freshwater sources typically fall between 0.65 and 0.75.

Can this calculator be used for seawater?

Yes. The calculator can estimate TDS in saline or hypersaline water. For more accurate results, the individual ion or evaporation method is recommended.

Does temperature affect conductivity-based TDS calculations?

Yes. Conductivity increases with temperature. This calculator accounts for temperature to provide more accurate readings.

Applications of TDS Monitoring

  • Water Quality Testing: Detects potential contamination or mineralization.
  • Aquariums & Aquaculture: Ensures optimal conditions for fish and aquatic plants.
  • Irrigation: Prevents crop damage from saline water.
  • Industrial Equipment: Avoids scaling and buildup in boilers and cooling systems.

Final Thoughts

TDS is a straightforward yet effective indicator of water purity. Whether you’re a researcher, a farmer, or managing a water supply, this calculator provides an easy way to measure and understand water composition using the data you have.