Phigenics Validation Test (PVT)

The Phigenics Validation Test is a patented field method for the quantitative determination of viable Legionella and total heterotrophic aerobic bacteria. The method has been proven reliable for determining viable cell concentrations of Legionella pneumophila, Legionella species and total heterotrophic aerobic bacteria in building water systems. Compared to standard methods, the new protocol has been shown to be more accurate, faster and more convenient.

The Problem

Currently, measurement of viable Legionella using standard culture methods usually requires shipment of water samples to an analytical laboratory. Results from these analyses are typically received 12-14 days after the sample is taken from the building water system. This delay can leave facility managers in a holding pattern while they wait for results. Shipment of water samples causes unpredictable changes in many samples; viable bacteria increase during transit in some and in other samples they decrease. These inaccuracies in the test results and the long delay before receiving test results cause serious difficulties for facility managers.

The Solution

The patented Phigenics Validation Test (PVT) completely eliminates the need to ship water samples, thereby giving more reliable data about the water system. The PVT is a field sampling protocol to obtain viable cell counts (CFU/ml) for the following:

• Total heterotrophic aerobic bacteria
• Legionella pneumophila (serogroup 1 and serogroups 2-14)
• Non-pneumophila Legionella species

Data is obtained for the exact moment when the PVT field sampler contacts the water sample

• Shipment of water samples to laboratory is not required
• Time required to obtain results is reduced 75-80% compared to the Standard Method for Legionella.

Test results including quantitative viable cell counts of Legionella, digital photographs of the field samplers, and chain-of-custody authenticity labels are emailed, typically within 2-3 days of sampling. The PVT is useful for validation, under operating conditions in the field, that this known bacterial hazard has been effectively controlled.

The Benefits

Compared to the Standard Methods for total bacteria and Legionella, the Phigenics PVT is:

• More Accurate because water samples are not compromised during shipment to the laboratory.


• Faster because time is not wasted during transit of water samples to the lab.


• Well Documented because results are captured in an easy-to-read report and accompanied by digital photographs of the field samplers and chain-of-custody authenticity labels.


• More Convenient because results for total bacteria AND Legionella bacteria are obtained and archived by the Phigenics Analytical Services Laboratory in a standardized protocol for future reference.

Tests Offered

PVT-Field: The PVT Field is a test specifically designed to detect and enumerate Legionella at the exact time the water is sampled. The PVT Field kit consists of one EPA vial (for sample collection), two dipslides, and a vial of pH adjust. The dipslide contains a different medium on each side of the paddle. One medium is useful for enumerating the total heterotrophic bacteria count and Legionella, and the other medium contains selective agents to improve detection and enumeration of Legionella. An acid treatment further facilitates detection and enumeration of Legionella.

PVT-Plus: The PVT-Plus is a product that combines the PVT-Field and PVT-ISO tests. Dipslides and sample collection bottles are provided in the test kit. The dipslides and water samples are sent back to the laboratory to be processed. The PVT-Plus also includes a Molecular Marker Negative Screen, which can reliably indicate the absence of Legionella.

ISO, Standard Method: The Phigenics ISO is the Phigenics version of the ISO 11731 Standard Method. A water sample is collected in the bottle provided and the sample is shipped back to the laboratory to be processed.

PVT-THAB: The PVT-THAB is a test used to obtain the total heterotrophic bacteria count using Phigenics specially-designed dipslide at the time water is sampled. This test is not used to detect Legionella in water systems. The dipslides are sent back to the laboratory for analysis.

Phigenics Analytical Services Laboratory (PASL) is a CDC ELITE certified laboratory and is accredited in the National Environmental Laboratory Accreditation Program (NELAP). The methods used by the PASL to detect and enumerate Legionella have been validated against CDC prepared and standardized samples.

PVT Product Sheet

If you are interested in how the PVT can address the safety of water systems in your facility,
please contact Phigenics (630-717-7546).