Troubleshoot Guide: Bad Taste or Bad Smell

RO-45 Model

To help us diagnose the "Bad Taste or Smell" problem in your RO water, you would need to:

  • Check the TDS (contaminant) level at different points along the system.
  • Do a taste test at these points to identify where the water begins to taste bad.
  • Test the "waste water" to "pure water" ratio.

(Test: waste ratio, test tds & taste at: C3, F, G)


Please do the test steps listed below. Use the TDS meter (water quality tester) to test your TAP and Filtered water. Please see the figure below.

Test #1: Waste Water Ratio

Purpose: The RO takes 4-5 gallons of waste water to make 1 gallon pure water. So the "Waste Ratio" should be 4:1 to 5:1. If wastewater is less than this ratio, the TDS will be high. Test waste ratio as follows:

  • Close the tank valve.
  • Remove the BLACK drain line from the drain saddle. Put line in a bucket to catch the wastewater.
  • Remove the Clear line from point C3. Pure water will flow out of the line in a small stream.
  • Fill up an 8 oz cup from this line ---> this is PURE water from the membrane.
  • Measure the amount of WASTE water the RO generated to make the 8oz pure water.
  • Are you getting about 4 - 5 cups of waste water for 1 cup of pure water?
  • Record the "waste ratio". Give us the number.

(The C-3 port has quick-connect type fitting. To remove clear line from port, see "How to Use Quick-Connect Fittings" at this link:

Test #2: Point C3 TDS & Taste:

Purpose: Test TDS and taste of water at point C3. This is to confirm if the stage-4 membrane is in good condition. Do test as follows:

  • Remove the Clear line from point C3.
  • Catch some water from this line. Test TDS. Record TDS for point C3.
  • Do a taste test of water from this line. Record your finding for point C3.

Test #3: Point F TDS & Taste

Purpose: Test TDS at point F. This is to confirm that the ASO valve is OK, and is not causing the "funny" taste.

  • Remove the CLEAR line from point F (plastic Tee-fitting).
  • Catch some water from this line. Test TDS. Record TDS for point F.
  • Do a taste test at point F. Record your finding.

Test #4: Point G (Tank Line) TDS & Taste

Purpose: Test TDS at point G. This is to test tank water's TDS, and taste.

  • Remove the YELLOW tank line from point G (the other end of plastic Tee fitting).
  • Turn ON the tank valve.
  • Catch some water from this line. Test TDS. Record TDS for point G.
  • Do a taste test at point G. Record your finding. Test #5: TAP water TDS
  • Get some TAP (unfiltered) water from your sink faucet.
  • Do TDS test. Record your tap water's TDS.

Please give us the TDS number for points: C3, F, G. Also, tell us how water tastes at each point. We need that info to diagnose further.

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