For industrial and commercial facilities, managing water quality isn’t just about aesthetics—it’s about protecting equipment, ensuring regulatory compliance, and reducing operational costs. One of the most critical water quality indicators is Total Dissolved Solids (TDS). These dissolved ions and particles may be invisible to the eye, but they have a direct impact on system efficiency, equipment longevity, and treatment effectiveness.

At EAI, we specialize in helping clients maintain high-performing water systems across the United States. With more than 35 years of expertise, we provide tailored water treatment programs designed to manage parameters like total dissolved solids – so your boilers, cooling towers, and purification systems can run reliably and efficiently. In this article, we’ll break down what TDS is, where it comes from, how it’s measured, and how managing it plays a key role in industrial water treatment.

What Is Total Dissolved Solids (TDS)?

Total Dissolved Solids (TDS) represent the combined amount of inorganic salts and trace organic materials dissolved in water. Common components include dissolved calcium carbonate and, magnesium, sodium, potassium, chlorides, sulfates, and bicarbonates. These dissolved substances can affect water’s taste, conductivity, scaling potential, and compatibility with treatment processes.

In industrial applications, TDS levels are more than a measurement of water purity – they’re a leading indicator of potential system issues. Elevated TDS can result in scale deposits, fouling, corrosion, or premature equipment failure.

Types and Sources of Total Dissolved Solids

TDS originates from both natural and man-made sources. Understanding where it comes from is essential to identifying risks and treatment needs.

Natural sources of dissolved solids include:

• Mineral runoff from soil or rock formations
• Calcium and magnesium from groundwater
• Sodium carbonate and sodium chloride from seawater intrusion in coastal regions

Human-made contributors include:

• Agricultural runoff (fertilizers, pesticides)
• Industrial discharges and wastewater
• Urban stormwater and sewage

Each source introduces different contaminants, which may be benign – or harmful – depending on the application. High TDS and water temperature in boiler feedwater, for example, increases the risk of scaling on heat transfer surfaces, reducing energy efficiency and damaging tubes or tanks.

Measuring TDS in Water

TDS is usually measured in parts per million (ppm) or milligrams per liter (mg/L). There are two primary methods of measurement:

1. Gravimetric Method (Lab-Based): Water is evaporated and the residue is weighed. This provides precise TDS measurement but is time-consuming and impractical for daily use.

2. Conductivity Meters (TDS Meters): Most field testing relies on electrical conductivity (EC). Since dissolved ions carry electric current, EC readings can be converted into TDS estimates using a conversion factor (typically 0.5–0.7 depending on the ions present).

Using a TDS Meter

TDS meters are useful in both industrial and household settings. To use one effectively:

• Calibrate the meter per manufacturer instructions
• Submerge the probe in the sample water (industrial water or drinking water) until stable
• Record the TDS value in ppm or mg/L
• Rinse the probe with distilled water after use

While meters give fast readings, they should be cross-checked periodically with lab tests—especially when operating in high-stakes systems like boilers, RO, drinking water, or pharmaceutical-grade water.

Interpreting TDS Results

For most applications:

• <300 ppm – Ideal for drinking water and process water
• 300–600 ppm – Acceptable but may affect taste or performance
• 600–1,000 ppm – Requires treatment for sensitive equipment or consumption
• >1,000 ppm – Generally considered unsuitable for direct use

TDS levels aren’t regulated by the EPA as a primary contaminant in drinking water quality, but they are included in the Secondary Drinking Water Standards with a recommended limit of 500 ppm. This limit is set based on taste, corrosion potential, and interference with industrial processes.

TDS Guidelines by System Type

Different systems have different tolerances when it comes to Total Dissolved Solids. Managing TDS within the recommended range helps prevent scale, corrosion, membrane fouling, and regulatory violations. Below is a general guide based on typical industry standards. Always verify with equipment manufacturers and local regulations.

Boilers:

• Low-Pressure (below 150 psi): < 3,500 ppm TDS
• High-Pressure (above 600 psi): < 100 ppm TDS (often tighter, depending on design and steam purity requirements)

Cooling Towers:

• Typical Range: 1,000–3,000 ppm TDS
• Tolerances vary with cycles of concentration, makeup water quality, and inhibitor chemistry. High TDS increases scaling and corrosion risks—especially with calcium, chloride, or sulfate ions.

Reverse Osmosis (RO) Feedwater:

• Ideal: < 500 ppm TDS
• RO membranes are sensitive to high TDS. Levels above 1,000 ppm may require pretreatment with softening, antiscalants, or carbon filtration.

Closed Loop Systems (Chilled or Hot Water):

• Target Range: 50–150 ppm TDS
• Closed loops should maintain low conductivity to minimize corrosion and biological growth. Periodic flushing and chemical treatment help maintain balance.

Humidifiers / Steam Injection Systems:

• Recommended: < 10 ppm TDS
• These systems atomize or vaporize water—any dissolved solids left behind can form deposits or be aerosolized, causing damage and indoor air quality issues.

Effects of High TDS on Operations

TDS levels affect more than water clarity or drinking water flavor. In industrial systems, elevated TDS levels can lead to:

1. Scaling: Calcium, magnesium, and other minerals can deposit on heat exchange surfaces, piping, and boiler tubes—reducing thermal efficiency and causing hot spots or blockages.

2. Corrosion: Certain ions, like chlorides and sulfates, contribute to electrochemical corrosion, weakening pipes, valves, and equipment housings.

3. Biofouling: Organic solids in TDS can serve as nutrients for microbial growth, particularly in cooling systems or areas with stagnant flow.

4. Reduced Efficiency in RO Systems: Reverse osmosis membranes have lower throughput and shorter life spans when treating high-TDS water, increasing maintenance and replacement costs.

Water Treatment Methods to Reduce TDS

Facilities with high TDS concentrations must implement targeted water treatment to protect infrastructure and maintain water quality. Common TDS-reduction technologies include:

Reverse Osmosis (RO): Removes up to 99% of dissolved solids ro water, through a semi-permeable membrane. Pretreatment is essential to avoid scaling and extend membrane life.

Deionization (DI): Uses ion-exchange resins to replace dissolved ions with hydrogen or hydroxide. Produces ultra-pure water but is best for low-volume or polishing applications.

Distillation: Boils water and condenses steam to separate solids. Effective but energy-intensive and slow, so it’s less common in large-scale water treatment process and systems.

Chemical Precipitation or Softening: Removes hardness-causing ions like calcium and magnesium through lime or soda ash addition. Useful for boiler feedwater prep.

Selecting the right method depends on influent water supply quality, system requirements, and regulatory compliance needs.

Where Water Treatment Fits into TDS Management

At EAI, we don’t just measure TDS—we design our water treatment plans with programs that keep it within operational targets. Whether you’re managing a steam-generating boiler, a chilled water loop, or an RO polishing system, controlling TDS is essential for performance, safety, and asset longevity.

Our services include:

• Boiler feedwater conditioning
• Pretreatment design and equipment selection
• Chemical dosing and monitoring for scale/corrosion prevention
• Periodic water analysis and system audits

By proactively managing low TDS, and other key water quality indicators, we help facilities reduce downtime, optimize chemical use, and extend the life of mission-critical infrastructure.

Best Practices for Monitoring and Controlling TDS

To maintain optimal TDS levels:

• Test regularly – Use field meters backed by lab analysis.
• Track trends – Sudden increases may signal contamination, leakage, or softener breakthrough.
• Match TDS to equipment – Boilers, cooling towers, and humidification systems have different TDS tolerances.
• Automate where possible – Inline sensors and data loggers can provide real-time alerts for deviations.

EAI supports facilities with water treatment setups and chemical dosing programs that help keep TDS under control.

Let EAI Help You Optimize Water Quality

Total Dissolved Solids (TDS) are a critical factor in water quality management. While they may not pose direct health threats at moderate levels in tap water, they affect taste, corrosion, scaling potential, and system performance—especially in commercial and industrial water systems.

By understanding the types, sources, and impacts of TDS, and applying appropriate monitoring and treatment strategies, facility managers can protect their equipment and ensure compliance with internal or regulatory standards.

EAI works with businesses to implement tailored water treatment programs that treat TDS and other key parameters—delivering reliable system performance with long-term cost savings. Let us help you optimize your water quality!