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TDS Meters - Total Dissolved Solids

How Pure Is Your Water? Find Out!

Learn more about using TDS meters and total dissolved solids in your water.

Every owner of a RO Reverse Osmosis System needs to know the TDS of the incoming feed water and the product drinking water.  You need a TDS meter to do this.

  1. TDS-N TDS Meter.  Test your water for total dissolved solids.
    TDS-N TDS Meter. Test your water for total dissolved solids.
    TDS-N TDS Meter. Test your water for total dissolved solids. Learn More
    $39.99 Special Price $27.00
  2. HM DIGITAL- TDS Meter EZ-HMD To Test for total dissolved solids in Water -1000
    TDS Meter EZ - HMD To Test For Total Dissolved Solids In Water
    TDS Meter - Tester To Test For Total Dissolved Solids In Water - Reverse Osmosis Membrane Tester Learn More
    $35.99 Special Price $19.99
  3. WATERPROOF EC / TDS / TEMP COMBO METER / PROFESSIONAL TESTER - HM Digital COM-100
    WATERPROOF EC / TDS / TEMP COMBO METER / PROFESSIONAL TESTER - HM Digital COM-100
    FOR THE PROFESSIONAL ! ------ COMBO METER / TESTER FOR EC / TDS / TEMP - WATERPROOF. The only handheld TDS meter / EC meter with full scale digital calibration. A water tester that is perfect for both consumer or commercial use. Ideal for all water quality testing, water purification applications, wastewater regulation, aquaculture, hydroponics, colloidal silver, labs & scientific testing, pools & spas, ecology testing, boilers & cooling towers, water treatment and more. Learn More
    $76.95 Special Price $59.99 As low as $47.99
  4. TDS Meter - Test For Total Dissolved Solids In Water - Reverse Osmosis Membrane Tester - TDS Meter
    TDS Meter - Test For Total Dissolved Solids In Water - Reverse Osmosis Membrane Tester - TDS Meter
    TDS Meter - Tester. The Only Way To Know If Your Reverse Osmosis RO Membrane Is Performing Correctly - Tests for TDS - Total Dissolved Solids. A Must For All RO System Owners. Compare Incoming Feed Water To Treated Water - Replace Membrane If Less Than 80% of TDS Is Being Removed - The lower the TDS level in the water, the more efficiently your body's cells actually get hydrated by the water that you drink. The higher the TDS levels in the water, the greater the probability of harmful contaminants that can pose health risks or hinder the absorption of water molecules on the cellular level. Simple to use for Reverse Osmosis membrane monitoring. We really like this tester and think that anyone who wants to know about the quality of their water should have one of these TDS Meter Testers to monitor their RO membrane. Learn More
    $49.99 Special Price $37.99 As low as $17.99
  5. TDS Meter Inline Water Tester DM1 - HM Digital Dual Mode Reading
    TDS Meter Inline Tester- Dual Mode Reading - Easily Installs Inline - Very Simple To Use
    TDS Meter - Dual Mode - Installs Inline - Check the TDS level with the push of a button. Now you can easily check to make sure the water from your reverse osmosis system is top quality. Measure the tap water coming in vs. the purified water going out of your system at any time. Very easy installation. FEATURES Displays TDS levels of the feed water and product water with in & out electrode probes. Highly efficient and accurate due to its advanced microprocessor technology. Auto-Off function conserves battery power. The unit shuts off automatically after 10 minutes of non-use. Comes equipped with John Guest Quick-Connect T-fittings as shown. Installs quickly and easily. SPECIFICATIONS Range: 0-9990 ppm Accuracy: ±2% Always know if your RO membrane is performing correctly! Learn More
    $49.99 Special Price $39.99 As low as $19.99
  6. HM Digital AP-1 AquaPro Water Quality Total Dissolved Solids Tester
    HM Digital AP-1 AquaPro Water Quality Total Dissolved Solids Tester
    HM Digital AP-1 AquaPro Water Quality Total Dissolved Solids Tester, 0-5000 ppm TDS Range, 1 ppm Resolution, +/- 2% Readout. HM Digital introduces its new AquaPro series, a line of handheld TDS/EC meters with a sleek design that's perfect for today's modern kitchen. The AquaPro digital water testers are the next generation for today's tech-savvy and health-conscience consumer. Learn More
    $42.95 Special Price $29.99 As low as $20.00
  7. TDS Water Meter Dual Mode Readings - DM2 HM Digital Professional Grade
    TDS Water Meter Dual Mode Readings - DM2 HM Digital Professional Grade - Easily Installs Inline - Very Simple To Use
    TDS Meter Dual Mode Readings - Professional Grade - Easily Installs Inline - Very Simple To Use. Measure the tap water coming in vs. the purified water going out of your system at any time. Use the meter to determine when the filters need to be changed. Highly efficient and accurate due to its advanced microprocessor technology. Displays TDS levels of the Feed Water and Product Water with in & out electrode probes. Auto-Off function conserves battery power. The unit shuts off automatically after 20 seconds. Dual Range - Measures from 0-999 ppm, with a resolution of 1 ppm. Learn More
    $69.99 Special Price $49.99 As low as $29.99
  8. Hanna ® TDS Calibration Solution Packet # 70032 For Water Testing TDS Meters
    Hanna ® TDS Calibration Solution Packet # 70032 For Water Testing TDS Meters
    Hanna ® TDS Calibration Solution 1382 PPM for calibrating TDS Meters / Testers to use for testing Reverse Osmosis RO Systems. # 70032 Learn More
    $8.99 Special Price $4.99 As low as $2.99
  9. TDS-3 Handheld Pure Water Testing Meter For Total Dissolved Solids
    TDS-3 Handheld Pure Water Testing Meter For Total Dissolved Solids With Carrying Case
    TDS-3 Handheld Pure Water Testing Meter For Total Dissolved Solids With Carrying Case. HM Digital. Features Ideal for commercial use. Includes a carrying case with belt clip. Highly efficient and accurate due to its advanced microprocessor technology. Hold Function: saves measurements for convenient reading and recording. Auto-off function: the meter shuts off automatically after 10 minutes of non-use to conserve batteries. Measurement Range: 0-9990 ppm. From 0-999 ppm, the resolution is in increments of 1ppm. From 1000 to 9990 ppm, the resolution is in increments of 10ppm, indicated by a blinking 'x10' image. Built-in digital thermometer Display: large and easy-to-read LCD screen. Factory Calibrated: our meters are calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver. TDS Range: 0 - 9990 ppm (mg/L) Temp. Range: 0 - 80 degrees Celsius Resolution: 1 ppm, 1 degree Celsius (also available in 10 ppm) Accuracy: +/- 2% ATC: Built-in sensor for Automatic Temperature Compensation of 1 to 50 degrees Celsius (33 to 122 degrees Fahrenheit) Power source: 2 x 1.5V button cell batteries (included) Battery life: 1000 hours of usage Dimensions: 15.5 x 3.1 x 2.3cm (6.1 x 1.25 x 1 inches) Weight with case: 76.5g (2.7 oz) Weight without case: 56.7g (2 oz) Learn More
    $59.99 Special Price $39.99 As low as $24.99
  10. HMI SP-3-Probe Set  HM Digital SP-3 Replacement Probe Set For  DM-1 TDS Meter
    HMI SP-3-Probe Set HM Digital SP-3 Replacement Probe Set For DM-1 TDS Meter
    HM Digital SP-3 Replacement Probe Set For DM-1 TDS Meter Learn More
    $19.99

Easy TDS Membrane Performence Calculator
See If It is Time To Replace Your Membrane

Simply enter your Feed Water TDS and RO Water TDS into the boxes above and click "Submit". The percentage of TDS Rejection will be displayed. We normally recommend membrane replacement once you drop below 75%. This may vary in areas with high TDS in the feed water.

See our selection of TDS meters under Water Tests


Be sure to check our Parts Departmentfor important parts such as TDS Testers, Replacement Tanks, O-rings,Housing Wrenches and more parts for your pure water filtration system.