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Female Scientist


T.V.C (Total Viable Count) also known as colony count is a good indicator for the general quality of a water source.  T.V.C is an environmental test so is incubated at 22C and 37C to give a general insight into bacteria growing in normal conditions within your process.

Colony counts (TVCs) are enumerations of the general population of heterotrophic bacteria present in water samples. 


Monitoring of water supplies for colony count bacteria can be useful for seeing trends in water quality or detecting sudden changes in quality. 

This test is designed to ascertain whether a water sample meets microbiological quality specifications and to indicate the presence or absence of any objectionable organisms.

TVC Testing UKAS

Stansted Laboratories is UKAS accredited to test for T.V.C's from the following sources:

  • Drinking Mains Tap Water

  • Drinking Bottled Water

  • Drinking Bowser/ Tanker Water

  • Recreational Swimming Pools

  • Recreational Hydrotherapy Pools

  • Recreational-Spa Pools

  • Industrial Cooling Towers

  • Cold water storage tanks

  • Closed heating Systems

  • Closed Chilled Systems​

Swimming pool colony count tvc
500ml Sodium thiosulphate bottle

Samples are collected in sterilized bottles pre-dosed with 1.8% sodium thiosulphate solution. During transit and when in storage, samples should be kept cool (2°C - 8ºC). Samples should be analysed as soon as practicable on the day of collection. In exceptional circumstances, if there is a delay, storage under the above conditions should not be exceeding 24 hours before the commencement of analysis


1 Environment Agency: Microbiology of Drinking Water (2012). Part 7 – Methods for the enumeration of heterotrophic bacteria by pour and spread plate techniques.

2 The Microbiology of Recreational and Environmental Waters (2000).

3 BG 50/2013 page 69-73 Section 27 and 28 -Water treatment for closed heating and cooling systems

4 Legionnaires disease: Technical guidance Part 1: The control of Legionella bacteria in evaporative  cooling systems HSG274 Part 1 Published 2013

5 Pool water treatment advisory group(PWTAG) Swimming pool water(treatment and quality standard for pools+SPA),published Nov 2017

6 SCA- Microbiology of Drinking Water (2020) – Part 7 – methods for the enumeration of heterotrophic bacteria by pour and spread plate techniques.

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