Correct use of a TDS Meter

We have recently started offering TDS Meters on our website, after it became apparent that many of our clients wanted a simple and effective solution to quickly test the water being used in their autoclave steriliser.

What is a TDS Meter?

A TDS Meter tests for Total Dissolved Solids (TDS), hence the name. It is a small, pen shaped device which can easily fit into a drawer or cupboard to be quickly accessed and used every time pure water is ready to use in an autoclave steriliser.

How does it work?

Each TDS Meter has a probe with two electrodes that pass an electric current through the water or liquid they are being immersed into. On this basis, the meter measures the conductivity of the liquid between the two electrodes – if the conductivity is high, this indicates a high concentration of dissolved solids such as minerals, calcium, chlorides etc. if the conductivity is low, this indicates a low concentration of TDS. 

Once the meter has measured conductivity, this is converted to a TDS reading on the meter in parts per million (PPM).  

•    If the water is above 10PPM you should not use this water in an autoclave.  
•    If below 10PPM you can use this water however it is best to use water between 0 and 5PPM.

How do you know it’s accurate?

•    It is important to calibrate any TDS Meter regularly, as recommended by the manufacturer. This is typically done using a calibration solution with a known value of TDS, and then adjusting the meter to match. 
•    It is also key to keep the probe clean and free of debris.

As long as the TDS Meter is regularly cleaned, maintained and checked, operation will remain accurate.

Why do we need to test water quality?

Testing the quality and purity of water being used in an autoclave is crucial for several reasons.

  • Maintenance – water that contains minerals and impurities can interfere with the sterilisation process and in some cases contaminate the equipment being sterilised within. These minerals and impurities can also adhere themselves to the inside of the autoclave, which can lead to breakdown and malfunction.
  • Compliance – there are strict regulations and requirements regarding sterilisation procedures in the healthcare sector and regularly testing water quality in sterilisation equipment aids compliance.
  • Safety – there are health risks associated with using water that is not pure enough for sterilisation of medical equipment, and testing helps to make sure that contaminated water is not being used.