Potatech+ Water Quality Laboratory

The Potatech+ kit enables an important step forward in water quality testing; combining digital measurements and microbiological testing to deliver a portable testing kit favoured by WASH Professionals

The latest version of the kit originally known as the JMP kit, the kit was designed for use by the Joint Monitoring Programme. A project run by UNICEF and WHO in conjunction with local partners, the programme monitors development indicators including water quality for under-served populations. Since 2016 the JMP has been tasked with monitoring progress towards Sustainable Development Goal 6, which includes the target of achieving universal and equitable access to safe and affordable drinking water for all by 2030.

Digital testing for wider scope and increased accuracy

Using digital instruments gives the advantage of increased accuracy and precision of results and allows access to a wider range of testing parameters. The kit includes a Photometer 7100 which uses the same reagent-based method as visual colour comparison methods, but analyses the colour of the sample digitally – this approach corrects some problems inherent in colour comparison:

  • Differences in colour perception – whilst true colour-blindness is rare, differences in the ability of users to see colour is not uncommon, and can result in incorrect results
  • Difference in light sources – visual testing relies on ambient light for illuminating the test and this can vary significantly from bright equatorial sunlight to cloudy skies to artificial indoor lighting
  • Decision making – the user is required to make a decision about the final result, which adds another significant source of error

Furthermore, the optical system used in the Photometer 7100 can detect smaller colour increments than the human eye, and delivers more precise results as a consequence.

Digital turbidity testing

The Potatech+ also includes the Turbimeter Plus, for digital turbidity measurement. The human eye can only detect turbidity to around 5 NTU, and so for fine measurement a meter is required. Turbidity is caused by suspended particles in water and turbidity measurement uses a specialised technique known as nephelometry – the light scattered by these particles is measured at 90◦ to the incident beam. Using this measurement array, in conjunction with a light source in the infra-red region means that the result is not subject to interference by colour in the sample.

The WHO recommended level for turbidity in drinking water is <5 NTU, however target levels for drinking water are commonly <1 NTU. At these lower levels turbidity has been investigated as a potential surrogate for microbiological contamination, especially for larger contaminants such as cryptosporidium oocysts.

As with all of the kits in the Wagtech range, the Potatech+has been designed for field monitoring of water quality parameters. The protective carry case contains all equipment required for field monitoring, including a testing work-surface for preparing samples.

For more information about the Potatech, contact our team.

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