Updated on January 17, 2024


Created on August 29, 2015

Compartment Bag Test (CBT) Kit

Aquagenx CBT is an on-site field testing kit for detection of E. coli and total coliform in water.

Developed By
  1. Aquagenx
Content Partners


Product Description

The Aquagenx Compartment Bag Test (CBT) is a portable water quality test that allows users to determine if drinking water contains E. coli bacteria. The test does not require electricity, cold chain, laboratories, trained technicians or specialized equipment. Water quality testing and monitoring are done in a few steps that generate quantified, color change results.

Target SDGs

SDG 6: Clean Water and Sanitation

SDG 3: Good Health and Well-Being

Target Users (Target Impact Group)

Household, Community

Distributors / Implementing Organizations

Implementing organizations are customers of Aquagenx and include agencies such as: International Federation of Red Cross and Operation Blessing International.

Competitive Landscape

Manufacturing/Building Method

Mass produced

Intellectural Property Type

Trade Secret

User Provision Model

Available for purchase via the Aquagenx site. Volume-based pricing is applied for CBT Kits. The kit is sold complete, not by individual test. A quotation request form is required to be filled by the customer.

Distributions to Date Status

Aquagenx has sold tens of thousands of CBTs that are used around the world. Interview with representative

Test types included

Coliform counts (E. coli)

Total Coliform



Equipment included

Bag, chemical reactant

Tests per kit

100 tests per kit

Detection range

Cannot enumerate

Processing time for one sample (hr)

20-48 hours

Additional materials required

Safety equipment

Power required (yes/no)


Complete kit weight (kg)

0.7 kg

Design Specifications

The CBT Kit is portable, compact and self-contained and includes built-in sample decontamination in the form of chlorine tablets. The CBT quantifies the Most Probable Number (MPN) of E. coli bacteria in a 100 ml water sample according to World Health Organization and US Environmental Protection Agency guidelines for safe drinking water. The steps for using the CBT are: 1. Collect Sample, 2. Mix Medium 3. Pour into Bag 4. Incubate 20-48 hours 4. Score Results Instruction and a video on how to use the CBT is available. The contents of CBT I Kit are: Aquagenx CBT EC+TC (100 MPN samples) Seal clips for Aquagenx Compartment Bag (25) Barcode asset tags (100) Arsenic tests (100) Fluoride meter (1) Fluoride reagents (100) pH/Conductivity/TDS meter (1) Stopwatch (2) Collapsible 20 liter bucket (1) Tape measure (1) 500 mL plastic sample bottle (1) Sturdy backpack (1) Kit Dimensions: 8 x 7.5 x 4.5 in; Kit Weight: 1 lb 9 oz

Product Schematics

Technical Support

Provided by Aquagenx

Replacement Components

Not available for replacement


Kit shelf life is based on the viability of the E. coli medium for which shelf life is one year from date of manufacture.

Manufacturer Specified Performance Parameters

The CBT quantifies the Most Probable Number (MPN) of E. coli bacteria in a 100 ml water sample according to World Health Organization and US Environmental Protection Agency guidelines for safe drinking water. The CBT gives results on par with more complicated, expensive and less portable tests.

Vetted Performance Status

Testing in Ghana, by MIT and the Wisconsin Department of Natural Resources – Water Quality Bureau, demonstrated that the CBT gave the highest ratings overall, for the E.coli results. Testing in Peru by University of North Carolina Gillings School of Global Public Health et al showed: (1) No significant differences between CBT test in the field, the CBT in the laboratory and the membrane filtration method in the laboratory for E.coli detection in household drinking waters in geographically diverse areas and (2) Previously untrained survey staff are able to obtain statistically comparable results to laboratory technicians and ranked the CBT a 9.3 out of 10 for overall use.


Decontamination of samples is required before disposal. The decontamination procedure is as follows: • Open bag and add 3 chlorine tablets to top of bag. Agitate bag until chlorine tablets dissolve. Let bag stand for 45 minutes. • After 45 minutes, pour liquid contents into a sink, toilet or hole in the ground and safely dispose of the empty bag

Complementary Technical Systems

For temperatures below 25°C, use of an insulated container or portable incubator is recommended during the incubation period.

Academic Research and References

Murcotta, S. et al., 2015,  Evaluation of Microbial Water Quality Tests for Humanitarian Emergency and Development Settings,  Humanitarian Technology: Science, Systems and Global Impact 2015, HumTech2015, Procedia Engineering: Volume 107, pp. 237–246.

McMahan, L. & Wang, A., et al., Evaluation of household microbial water quality testing in a Pilot Peruvian Demographic and Health Survey using the portable Compartment Bag Test (CBT) for E. coli, University of North Carolina Gillings School of Global Public Health [poster]

Knee, J. et al., Field Evaluation of a Low-cost Compartmentalized Bag MPN Method for the Detection and Quantification of E. coli in Stored Household Rainwater Samples Collected in Northeastern Thailand

Stauber, C., Miller, C, Cantrell, B. and Kroell, K., 2014, Evaluation of the Compartment Bag Test for the Detection of Escherichia coli in Water., J Microbiol Methods.

Weiss, P. et al., Microbial Quality and Safety of Well Water in Rural Nicaragua as Determined by Low-Cost Bacterial Test, School of Public Health, College of Human Medicine, Michigan State University [poster]

“Water Quality Field Test Kits,” Aquagenx | Water Quality Field Test Kits, 10-Sep-2013. Available: https://www.aquagenx.com/

“Testimonials,” Aquagenx | Water Quality Field Test Kits, 01-Jun-2013. Available: https://www.aquagenx.com/testimonials/

“Test Kits & Strips,” Hach.com. Available: https://www.hach.com/products/lab-equipment-and-supply/test-kits-strips 

Goal 6. (n.d.). Sdgs.un.org. Available: https://sdgs.un.org/goals/goal6 

“E. coli & Total Coliform Water Quality Test Kits,” Aquagenx | Water Quality Field Test Kits, 08-Nov-2018. Available: https://www.aquagenx.com/cbt-ectc/

“100 mL Water Quality Tests,” Aquagenx | Water Quality Field Test Kits, 10-Sep-2013. Available: https://www.aquagenx.com/buy/ 

“Portable Water Quality Test Kits,” Aquagenx | Water Quality Field Test Kits, 17-Sep-2013. Available: https://www.aquagenx.com/how-to-use-cbt-ectc/ 

“Aquagenx Compartment Bag test (CBT) performance evaluation data,” Aquagenx.com. Available: https://www.aquagenx.com/wp-content/uploads/2014/03/Aquagenx-CBT-Performance-Evaluation-Data_optimized.pdf 

“Compare ECTC to Other Tests,” Aquagenx | Water Quality Field Test Kits, 14-Sep-2022. Available: https://www.aquagenx.com/compare-cbt-ectc-to-other-tests/

Compliance with regulations

The CBT meets World Health Organization water quality recommendations for indicator organism (E. coli) and sample volume (100 mL).

Evaluation methods

Lab Evaluation of the E. coli Chromogenic Medium of the CBT versus Colilert Medium in Compartment Bag MPN Test Format: Lab performance data were collected in a university lab by college students who were trained to conduct the Compartment Bag Test (CBT). The 600 samples of water in this dataset were split into groups tested as 100-mL sample volumes and analyzed using (1) the CBT and Hi-E.coli chromogenic medium and (2) the CBT and Colilert medium. Both tests reported E. coli concentration as an MPN/100 mL. Within each test group, 180 samples were made at the 50 mL dilution and 120 samples were made at the 10 mL dilution. For each test group and within each dilution level, the incubation temperature of the water samples was divided among the three temperatures of 27° C, 37° C, and 44° C. For each incubation temperature-sample dilution combination, the 10 mL dilution had a sample size of 40 and the 50 mL dilution had a sample size of 60. All samples were tested in CBT compartment bags, so MPN counts for Colilert are equivalent to MPN counts for CBTs.

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