The choice of professionals for years, this compact instrument has been designed specifically to demonstrate and test Point of Use (POU) reverse osmosis or distillation systems. By measuring electrical conductivity, it will quickly determine the parts per million/Total Dissolved Solids (ppm/TDS) of any drinking water.

With a single “before and after” test, this handy device effectively demonstrates how your RO or distillation system eliminates harmful dissolved solids. It will also service test systems, including membrane evaluation programs.

Automatic Temperature Compensation: Why It Is Important

The graph below illustrates a TDS reading of a 500 ppm water sample tested with a non-temperature compensated conductivity meter. The same water sample appears to have a higher level of TDS when heated (and lower TDS when chilled). Actually, only conductivity readings change with temperature. TDS does not change.

Many instruments ignore the importance of temperature. Others require a separate thermometer for testing sample temperature, then manual adjustment of the meter. All Myron L^® instruments, however, feature fast and precise Automatic Temperature Compensation. The result: a more accurate, useful instrument.

How Conductivity Measures ppm/TDS

Total Dissolved Solids (TDS) conduct electricity. This conductivity allows measurement of the concentration of these salts directly in parts per million (ppm). However, the salts’ composition in waters can vary significantly by location. Since various salts pass current differently, it was necessary to determine an “average” ppm/ conductivity relationship. The Myron L^® Company established the “442” Standard over 55 years ago. It remains the world’s most widely accepted standard of its kind.

If You also Test pH:

Myron L^® offers instruments that check both TDS and pH, and are widely used throughout the RO industry.

• pH sensor is built-in for maximum protection
• Automatic temperature compensation
• Full calibration capability
• Many models available

Also see our RO-CHECK™ POU TDS Monitor

RO METERS™ Features:

• Instant and accurate TDS tests
• Electronic Internal Standard for easy field calibration
• Fast Auto Temperature Compensation
• Rugged design for years of trouble-free testing
• Simple to use

RO Meters™ Technical Specifications:

RO Meters™ Applications:

• Reverse Osmosis
• Drinking Water
• Distillation Systems

RO Meters™ Accessories, Replacement items and Solutions:

• Standard Solutions are used to periodically recalibrate instruments for greatest accuracy.  442-1000 (1000 ppm/TDS) is the type used in MyronL factory calibrations.

Model: 442-1000 (Specify quart, gallon or 2 oz.)instructions included.

• Porta-Pak Carrying Case: For use with all Myron L^® DS/pDS portable instruments. Foam lined and molded of sturdy ABS plastic.

Model: PTP

RO Meters™ Downloads:

• Data Sheet (PDF)
• Current Price List (PDF)
• Upcoming 2025 Price List (PDF)
• Operation Manual (PDF)