How to Efficiently and Effectively Detect Bacteria in Drinking Water

Poster Presentation

Prepared by T. Pan
Tecta-PDS, 382 king street east, KINGSTON, ON, K7K 2Y2, Canada

Contact Information: [email protected]; 416-200-9622


Drinking Water quality is key for the safety of consumer and routine sampling and testing of a drinking water supply is both a regulated requirement and the responsibility of all Water Suppliers. Of the many components of water, the microbiological content is a critical signal of potential contamination and is assessed through the detection of indicator organisms, E.coli and total Coliforms. The requirement to detect a single E. coli cell in a 100 mL water sample has been compared to the challenge of finding a single coffee bean in 40,000 Olympic-sized swimming pools.
The majority of microbiological water quality tests rely on traditional microbiological methods that were developed decades ago. Water samples are sent to a laboratory where they are filtered and subsequently placed into a growth culture media that is typically incubated for 24 hours. After the incubation period, each sample is inspected by a trained technician for signs of bacterial growth. Other methods use chemical additives in the growth media that cause colonies of specific target bacteria to change color or to appear fluorescent under ultraviolet light. While these methods are the current gold standard, they require 24-48 hours for samples to be transported, prepared, analyzed and only then laboratory results to become available. In the event of contamination, these delays in receiving test results increase the risk of public exposure, requiring costly remedial action or product recalls in commercial markets. Regular water quality events world-wide confirm this.
Born out of the Walkerton, Ontario disaster, where several people died from drinking contaminated water, the government of Canada issued a request for the development of a system which would eliminate all the risks that contributed to this tragedy. On this wish list was to have a fully automated system, requiring little to no human interaction and interpretation of results, fast results, portable, email / texting warning signals and no need for storage or shipping of samples to name a few.
TECTATM B-16 system was developed to meet all the requirements on the above list and to ensure that microbiological detection is rapid and simple. The innovative capabilities of the TECTATM B-16 system are made possible by a patented Polymer PartitionTM based optical sensor which is built into every test cartridge. Each cartridge contains pre-measured amounts of growth media that support the enrichment of any target bacteria that are present in the sample. As target bacteria such as E.coli or Coliforms begin to multiply, they emit a specific enzyme that interacts with a proprietary chemical substrate in the cartridge, releasing fluorescent molecules from the substrate. These fluorescent indicators rapidly move from the water sample into the polymer optical sensor located within the cartridge, enabling automated detection by a low-cost ultraviolet optical detection system that is built into the TECTA TM B-16 instrument.
The novel combination of the polymer-based optical sensor and ultraviolet optical detection system provides several key advantages. The fluorescent indicators are extracted and concentrated within the polymer of the optical sensor, facilitating both rapid detection at the earliest possible time and eliminating the risk of off-color samples or turbidity within the water sample obscuring the fluorescent indicator.
When placed in the TECTA TM B-16 instrument, the test is monitored continuously throughout the incubation process – providing alerts of contaminated samples as soon as possible and eliminating the requirement to wait until the end of a fixed incubation process (typically 18-24 hours). This unique early alerting capability allows the system to provide results within 2-18 hours, depending on the level of sample contamination.
In addition to a “presence/absence” result, the system is capable of providing an estimate of the number of bacteria that were present in the original sample – an important indicator of the level of severity of an adverse microbiological test result.
By using the TECTA TM B-16 system, water samples can be manually obtained and introduced directly into the TECTATMlert CCA cartridge that is pre-filled with all required test reagents, eliminating sample preparation and the requirement for sample dilution. Samples from municipal water distribution systems, or from points of use in industrial process water systems, are then processed by a compact desktop instrument located in close proximity to the point of sampling by personnel who do not require extensive microbiological training, saving sample transport costs and providing the fastest possible results by ensuring that samples are tested as soon as they are obtained.
The TECTA TM B-16 is the only automated system approved by US EPA for drinking water. EPA’s ETV program validated the system for on-site testing within a utility; the system has AOAC PTM approval in several matrices. The system has been adopted as the method of choice in over 25 countries, to utilities, bottling plants, government agencies (Department of Health; Department of Environment), commercial laboratories, militaries, and industrial plants. Customers in the US include Fulton County, Baltimore, LADWP, MWD and LVVWD.