What are cooling water dipslide tests?

Cooling water dipslides test for bacteria (TVC), yeasts and moulds (fungi). They feature two different types of agar to achieve this. On one side of the dipslide there is a Nutrient Agar (with TTC dye) which tests for aerobic bacteria (colonies grow as red spots), on the other side is a Malt Extract agar which detects yeasts and moulds.

To use the dipslides, dip the slide into your sample then incubate the dipslide. After incubation, you can then count the colonies / spots and compare with the chart provided. A step by step pictorial guide can be found below.

Why do I need to test cooling water for bacteria?

It is important to test the 'general health' of cooling water. You can do this using our cooling water dipslides. Although these displides will not test for legionella specifically, they will indicate if you have large bacterial growth which could potentially make the water a breeding ground for legionella or it could indeed contain the bacteria. As detailed in our article 'Dipslides for legionella testing' 

"If bacteria is present, we suggest that you conduct further tests to see if Legionella is one of the organisms in the system. Even if legionella is not identified, the presence of other organisms can support legionella by producing the organic nutrients that it needs to thrive.''

For evaporative cooling systems, the HSE (Health and Safety Executive) recommend that:

"You should monitor the effectiveness of the microbial control using weekly dip slides and periodic legionella analysis". 

In line with this guidance, we recommend regular dipslide tests (weekly) as well as routine quarterly legionella lab tests.

This kit will help you comply with:

New York Regulation: 10NYCRR 4-1 Maintenance Program

'(1) a schedule for routine bacteriological culture sampling and analysis to assess microbiological activity at intervals not to exceed 30 days while the cooling tower is in use, and that requires additional bacteriological culture sampling and analysis, as needed, to validate process adjustments;'

Please note, you will also be required by NY law to conduct specific legionella culture tests within 14 days of seasonal start up and at least every 90 days thereafter.

More information: https://regs.health.ny.gov/content/section-4-14-maintenance-program-and-plan

HSE ACOP L8 Maintenance and Testing Guidelines

The ACOP L8 documentation (http://www.hse.gov.uk/pUbns/priced/l8.pdf) refers to document 'Part1: The control of legionella bacteria in evaporative cooling systems' (http://www.hse.gov.uk/pUbns/priced/hsg274part1.pdf) for further technical guidance on cooling systems and how to comply with regulation.

European Technical Guidelines for the Prevention, Control and Investigation, of infections caused by Legionella species

European Technical Guidelines 2017: Minimising the risk from Legionella infections in building water systems:

(3.67): 'The effectiveness of the microbial control should be monitored using weekly dipslides and periodic Legionella analysis...'

More information: https://www.ecdc.europa.eu/sites/default/files/documents/Legionella%20GuidelinesFinal%20updated%20for%20ECDC%20corrections.pdf

Industry sectors

• Industrial cooling towers
• HVAC systems

These facilities can be based at a multitude of locations such as:

• schools
• offices
• hotels
• hospitals
• residential / care homes
• plants
• refineries

How to use Cooling Water Dipslides

Simply remove the dipslide and immerse in the cooling tower water sample for approx 10 seconds. Remove dipslide and allow to drain for a few seconds, then replace the slide back into the tube and incubate for a minimum of 24 hours (up to a maximum of 48 hours).

A comparison chart is included so you can easily compare your results.

Step 1 : Remove slide

Carefully remove the sterile cooling water dip slide from its tube ensuring that no contact is made with the agar (to avoid contamination).

Step 2 : If Surface Testing

For surface testing, press the cooling water dipslide onto the surface. If needed, place a finger on the bottom of the slide (on the plastic, not the agar) to apply extra pressure.

Step 2 : If liquid testing

For liquid testing, immerse the cooling water dipslide into the fluid for 10 seconds then remove and allow to drain for a few seconds.

Step 2 : If swab testing

Apply a sample of the test substance to a sterile swab and gently apply to the agars.

Step 3 : Incubate Slide

Label the tube with the included stickers then place the slide into an incubator and allow to incubate.

Step 4 : Compare results

Count the amount of colonies that have grown on the slide and compare them to the comparison chart provided.

Cooling Water Dipslide Features

Flexible Paddle

Each dipslide features a virtually unbreakable and flexible paddle allowing for even, full surface testing.

Easy Run Off Design

Due to the design of the dipslide, fluids will drain off quickly during testing.

Recessed Handle

Each slide has a handle built into the lid that is recessed to help keep your fingers dry during testing.

Side Indicator

One side of the slide will have a circle indicator so you know which side was used for testing which type of contaminant.

Dual Sided

Each dipslide is dual sided to allow multiple contamination testing with one test.

Thick Reliable Agar

Each agar is thick (approx 4mm) and raised above the dipslide to allow for easy surface testing.

Reading the results

	Nutrient Side
Level of infection in liquids (CFU/ml)	102	103	104	105	106	107
Approx colonies per agar	2	12	60	200	500	600+
HSE.gov.uk advice for evaporative cooling systems	System under control: Good general microbial control and no action required		Caution: Review programme operation: Ensure the water treatment programme and system operation is operating correctly. Adjust the biocide dosage if appropriate and resample after 24 hours.		Action: Review programme operation and implement corrective action: As a precaution, the system should be shot dosed with an appropriate biocide or the level of continuous dosage of biocide should be increased. The system should then be resampled after 24 hours to determine the effectiveness of the corrective action. If the high count persists, the control measures should be reviewed and the risk assessed to identify any necessary remedial actions.
Example Image
Level of infection on surfaces (CFU/cm2)	0.4	2.5	12	40	100	250

	Malt Extract Side
Level of yeasts in liquids (CFU/ml)	102	103	104	105	106	107
Approx yeasts colonies per agar	2	12	60	200	500	600+
Example Image
Level of yeasts on surfaces (CFU/cm2)	0.4	2.5	12	40	100	250

	Malt Extract Side
Level of moulds	Light		Medium		Heavy
Example Image

Additional Details

Product Reference : CWBTM2
Internal catalogue reference : DS001-69

Downloads

(1.75MB)

BTM2 Datasheet
BTM2 Dipslide Datasheet (PDF)
Download

(1.77MB)

Malt Extract Comparison Chart
Malt Extract comparison chart in JPG format
Download

(436.23KB)

MSDS
MSDS Sheet for Dipslides
Download

(1.62MB)

Nutrient Comparison Chart
Nutrient comparison chart in JPG format
Download