Water quality is crucial for industrial, commercial, and residential applications. One of the most important parameters in water treatment is Total Dissolved Solids (TDS). High TDS levels can affect taste, efficiency of industrial processes, scaling, and corrosion in water treatment systems. Understanding TDS, how it is measured, and the best methods to reduce it is key to achieving high-quality purified water.
In this article, we’ll cover:
- What Total Dissolved Solids (TDS) are
- How TDS affects water quality
- TDS measurement methods
- The best water treatment technologies for TDS reduction
- Industry applications where TDS monitoring is critical
What is Total Dissolved Solids (TDS)?
Total Dissolved Solids (TDS) refer to the amount of dissolved substances in water, including minerals, salts, metals, and organic matter. TDS is measured in parts per million (ppm) or milligrams per liter (mg/L).
Common TDS components include:
- Calcium (Ca²⁺) – Contributes to scaling in pipes and equipment
- Magnesium (Mg²⁺) – Causes water hardness and scaling
- Sodium (Na⁺) – High levels can affect taste and health
- Chloride (Cl⁻) – Contributes to corrosion in pipelines
- Sulfates (SO₄²⁻) – Can cause bitter taste and scaling
- Heavy metals (Iron, Lead, Copper, etc.) – Toxic contaminants that require removal
Why Does TDS Matter?
TDS levels impact water taste, health, and industrial performance. Depending on TDS concentration, water may require treatment.
| TDS Level (mg/L or ppm) | Water Quality Category | Effects & Applications |
| 0 – 50 | Ultra-Pure Water | Used in electronics, pharmaceuticals |
| 50 – 150 | Excellent | Preferred for drinking water |
| 150 – 300 | Good | Used in commercial filtration |
| 300 – 600 | Acceptable | Requires basic filtration |
| 600 – 900 | Poor | Causes scaling and corrosion |
| 900+ | Unacceptable | Requires advanced treatment (RO, distillation) |
Ideal TDS for Drinking Water: Below 300 ppm
TDS Limit for Industrial Use: Varies by application (e.g., Boilers < 50 ppm, Cooling Towers < 500 ppm)
How to Measure TDS in Water?
TDS can be measured using the following methods:
1️⃣ Digital TDS Meter
- Portable and easy to use
- Provides instant readings in ppm
- Ideal for home, commercial, and industrial use
2️⃣ Electrical Conductivity (EC) Method
- Measures conductivity of water, which correlates with TDS
- Used in lab and industrial settings
3️⃣ Gravimetric Method (Laboratory Testing)
- Most accurate but requires specialized equipment
- Used for research and high-precision applications
Effects of High TDS on Water Treatment Systems
High TDS levels negatively impact water treatment processes. Problems caused by high TDS include:
- Scaling & Fouling: Minerals such as calcium and magnesium deposit inside pipes and membranes, reducing efficiency.
- Corrosion of Equipment: High chloride and sulfate levels can damage pipelines, boilers, and heat exchangers.
- Poor Taste & Odor: High TDS water often has a salty, bitter, or metallic taste.
- Reduced Efficiency in Industrial Applications: Boilers, cooling towers, and reverse osmosis systems require low-TDS water for optimal operation.
How to Reduce TDS in Water?
There are several effective water treatment methods to remove TDS:
1️⃣ Reverse Osmosis (RO) – Best for TDS Removal
- Removes up to 99% of dissolved solids
- Ideal for drinking water, industrial use, and desalination
- Common in residential RO filters, industrial RO plants, and seawater desalination
2️⃣ Distillation
- Heats water to evaporate and remove impurities
- Produces ultra-pure water
- Used in pharmaceuticals and laboratories
3️⃣ Deionization (DI) / Ion Exchange
- Removes charged ions like calcium, magnesium, sodium, and chloride
- Commonly used in boiler feedwater and ultrapure water applications
4️⃣ Activated Carbon Filtration (For Taste Improvement)
- Absorbs organic contaminants and chlorine
- Does not remove dissolved salts but improves water taste
TDS Reduction for Different Applications
Drinking Water Filtration
- Solution: Reverse Osmosis or Distillation
- Target TDS: Below 300 ppm
- Reason: Improves taste and removes contaminants
Industrial Water Treatment
- Solution: Reverse Osmosis + Deionization (RO/DI Systems)
- Target TDS: Below 50 ppm
- Reason: Prevents scaling and ensures high efficiency
Seawater Desalination
- Solution: Seawater Reverse Osmosis (SWRO)
- Target TDS: Below 500 ppm
- Reason: Converts seawater (TDS ~35,000 ppm) into fresh water
Boiler Feedwater Treatment
- Solution: Reverse Osmosis + Softening
- Target TDS: Below 20 ppm
- Reason: Prevents scaling and damage in high-pressure boilers
Final Thoughts: Why Monitoring TDS is Essential
- TDS directly impacts water quality, taste, and industrial performance.
- High TDS causes scaling, fouling, and corrosion in water systems.
- Reverse Osmosis (RO) is the most effective technology for TDS reduction.
- Measuring TDS regularly helps in selecting the right water treatment process.
By maintaining the right TDS levels, industries and households can ensure safe, clean, and efficient water usage.