Blog Details

Water is the essence of life, yet millions worldwide still lack access to safe drinking water. Among the numerous challenges in achieving universal water safety, the time-consuming and costly nature of traditional water quality testing remains a significant barrier—particularly in remote areas where sample collection, transportation, laboratory analysis, and result interpretation consume substantial resources.

The World Health Organization (WHO) and UNICEF are collaborating to revolutionize this process through the development and deployment of portable water testing tools. These innovations aim to make on-site water quality assessment faster, more affordable, and easier to implement, bringing the world closer to achieving global water safety goals.

To ensure the reliability of portable testing devices, WHO established a technical advisory group in 2019 and developed a comprehensive evaluation protocol. The assessment focuses on tools designed to detect Escherichia coli (E. coli), a key indicator of fecal contamination in water.

The evaluated tools fall into two categories based on their quantification methods: colony counting systems and suspension-based measurements that use Most Probable Number (MPN) statistical methods.

Most quantitative portable tools in the evaluation employ colony counting techniques. The majority use membrane filtration with 100 mL samples, though two products analyze 1 mL samples without filtration. One innovative system utilizes a gel medium that enables direct colony counting without membrane filtration.

Participating colony counting systems include:

• Compact Dry EC plates (1 mL)
• Compact Dry ECO plates (1 mL)
• Compact Dry ECO plates with membrane filtration (100 mL)
• 3M Petrifilm SEC plates with membrane filtration (100 mL)
• Sartorius Chromocult Nutrient Pads with membrane filtration (100 mL)
• Delagua kit with membrane filtration and lauryl sulfate broth (100 mL)
• Trace2o AquaSafe WSL20 kit with membrane filtration and lauryl sulfate broth (100 mL)
• Hach MEL kit with membrane filtration and m-ColiBlue24 medium (100 mL)
• Trace2o WaterScope with membrane filtration (100 mL)
• Aquagenx gel EC CFU bag (100 mL)

This category includes tools that partition samples into multiple subsamples using proprietary compartments or wells, then calculate contamination levels through standard statistical MPN methods. For instance, the Fluidion ALERT LAB measures optical changes in absorbance and fluorescence over time to determine contamination levels.

Other suspension-based tools use 10 or 100 mL samples to indicate E. coli presence. For quantitative results, 100 mL samples are divided into 96 subsamples of approximately 1 mL each in deep-well plates. The MPN value is calculated based on positive well counts after incubation.

Participating suspension-based systems include:

• HiMedia HiSelective (100 mL)
• EC Blue (100 mL)
• AquaChrom ECC (100 mL)
• Hach Pathoscreen (100 mL)
• Resorufin (100 mL)
• IDEXX MPN tubes (10 mL)
• ECC MPN (100 mL)
• Aquagenx Compartment Bag Test EC+TC MPN (100 mL)
• Palintest Colitag MPN (100 mL)
• Fluidion ALERT LAB (40 mL)

In collaboration with WHO, UNICEF launched the Rapid Water Testing project to accelerate the development of next-generation field testing tools. The initiative established a Target Product Profile (TPP) outlining the ideal characteristics for field testing devices, first published in September 2016 and updated in December 2019 and November 2022.

In May 2022, UNICEF partnered with Nigeria's Federal Ministry of Water Resources to field-test two new rapid water testing methods in Abuja's rural communities. The week-long evaluation assessed various water sources including boreholes, river water, and treatment facilities from the Abuja Water Board.

One prototype device provided total coliform and E. coli results within one hour, while another delivered general biological readings in just 15 minutes. The field tests provided developers with crucial feedback about usability in resource-limited settings and practical implementation challenges.

UNICEF and WHO continue to collaborate with developers and industry partners to establish an evaluation framework for these products. They've partnered with AOAC International to develop performance testing methods for innovative products that don't rely on incubation, colony counting, or MPN analysis.

Through these concerted efforts, portable water testing tools are poised to play an increasingly vital role in achieving global safe water objectives, particularly in underserved communities where traditional laboratory testing remains impractical.