Report on the Use of the Product CoolerClean

to Sanitize Water Coolers

September 2000

Prepared for:

Hygienic Solutions B.V.

P.O. Box 17

1130 AA Volendam

The Netherlands

Tel: +31 – 299 – 32 33 09

Fax: +31 – 299 – 35 17 51

Prepared by:

Watermark Consultancy

11 Hawkesbury Drive

Calcot

Reading RG31 7ZP UK

Tel: +44 – 1189 420 194

Fax: +44 – 1189 454 105

1. INTRODUCTION

In Europe bottled water from coolers is being subjected to increasing scrutiny as the cooler market continues its dynamic expansion in an area where traditional bottled water has long dominated the market.

Sanitization of coolers and the use of coolers that are proof against microbial contamination from the working environment are key issues in attracting new cooler customers and retaining existing ones.

Sanitisation of coolers at 13 week intervals is compulsory for membership of the UK Bottled Water Cooler Association (BWCA) and is recommended for all members of the European Bottled Watercooler Association (EBWA) and its affiliated National Associations. The use of coolers with a bayonet fitting and air filter is also required.

As the industry has become more sophisticated so has its customers. Stringent Health and Safety standards mean that the microbiological condition of watercoolers and the water they dispense are often checked. This has highlighted the problems of biofilm and colonisation of tap mechanisms with organisms such as coliforms and Pseudomonas aeruginosa. Bottled water contains no anti bacterial agents and the development of such organisms is inevitable if they gain entry.

Thus the focus is now not on whether a cooler has been sanitised but whether it has been sanitised effectively.

Over the years cooler companies developed a range of cooler sanitisation methods using a range of chemicals not all of which were effective. Chemical companies were unable to give specific advice as they had no experience of the unique conditions of the industry. For examples products designed for washing glasses or cleaning beer lines were some of the more relevant chemicals offered. There has been a dearth of chemicals designed and packaged specifically for use in cooler care.

CoolerClean is a notable exception

The purpose of this investigation was to check the performance of CoolerClean Rinse which is intended for use during the full 13 week sanitisations recommended by EBWA. If successful this trial would mean that customers have a cooler care method that does not leave potentially dangerous residues and is known to be effective. This information is simply not available for most other methods and chemicals although ozonators are an exception.

The opportunity was also taken to check CoolerClean Spray which is intended for customer use between santisations or to deal with taps in association with other cooler care methods such as ozonation.

2 SANITISATION

Sanitisation is generally a two stage operation. It is cleaning followed by disinfection. The presence of scale and biofilm may reduce the effect of disinfectants so precleaning or descaling is likely to be necessary with most waters although this is not likely to be an onerous task with low TDS waters.

In some cases cleaning may be purely physical using cloths or brushes in others detergents or descalers may be necessary

3 SCALING

Many waters used in European coolers have high calcium levels and cause scaling - especially of the hot tank if fitted. Scale deposits can cause overheating or blockages of the hot tank and demand frequent descaling.

Scale deposits may also form on the interior surfaces of the reservoirs of coolers. Such scale can protect micro-organisms from sanitizers. Scale removal is a key part of cooler sanitization procedures.

4 BIOFILM

Biofilm is a gelatinous layer of micro-organisms that coats surfaces in contact with aqueous liquids. Coolers are prone to a build-up of biofilm on the interior surfaces. It can be felt as a slime on wet reservoir sides, bottle caps, bayonet systems and pipework. Biofilm is often accompanied by scale formation in coolers. The matrix of biofilm can afford considerable protection to bacteria growing within it. Left undisturbed, biofilm will eventually begin to shed bacteria into the water being dispensed by the cooler. This happens after about 3-4 months, depending on water type and other variables such as the material of the surface concerned. Up to this point, biofilm has little or no effect on water quality, despite often containing large numbers of micro-organisms. Recent work has shown that bacteria within biofilm are protected against the action of many biocides.

The problem bacteria Pseudomonas aeruginosa is common in biofilms and can prove very resistant to many disinfectants including chlorine based compounds. It can even metabolise some less aggressive disinfectants

5 COOLER CLEAN

CoolerClean is an alcohol based peroxide disinfectant. Peroxide is known to be much more effective against biofilm protected bacteria than most other disinfectants. Its only real rival is peroxyacetic acid which also contains peroxide.

Peroxide quickly breaks down to leave water and oxygen

6 METHODS

There are two ways to assess the effectiveness of the disinfection of food or water equipment. The simplest way is to inoculate the equipment with a culture of an indicator organism such as E. coli in order to soil it. The alternative method is to examine the equipment after a period of prolonged use. The machine is then sanitized and attempts made to recover the organisms after sanitization. This can be done by rinsing with sterile water or by swabbing interior surfaces, which is more thorough and will reveal hidden areas where contamination may remain.

If time permits the second method is preferable for water dispensing equipment such as bottled water coolers, plumbed in (point-of-use) coolers, ice makers or even vending machines. Such machines are sanitized every 3 months or so and in consequence build up an internal coating of biofilm between sanitizations (see para. 4). Such biofilm can be difficult to remove and can harbour micro-organisms such as Pseudomonas aeruginosa and coliforms. Taps and the spike system are especially prone to such contamination.

Therefore before microbiological tests were carried out 13 coolers of assorted make that were held back from sanitisation at the end of their 13 week cycle. The coolers and the premises for carrying out the trial were provided by the Classic Water company of Coulsdon, Surrey, UK. There codition varied considerably as they were chosen at random

The coolers had had their bottles removed but had been allowed to retain water in their reservoirs. This was important as the desire was that any biofilms should not be allowed to dry out

The water used was a chalk-derived Spring Water with high scaling properties and a typical mineral composition as shown below:

mg/litre

Total hardness 242

Calcium 123

Total solids 420

6.1 Coolers

The coolers used were as follows:

1 Elkay h&c table top

2 Elkay cold only table top

3 Elkay cold only table top

4 Elkay stainless reservoir cold only

5 Elkay ABB (plastic reservoir) c&c

6 Elkay ABB (very dirty and smelly) h&c

7 Elkay stainless h&c

8 Elkay stainless h&c

9 Elkay stainless h&c metal bodied

10 Elkay stainless cold only

11 Sunroc new model h&c

12 Sunroc new model h&c

13 Elkay cold only table top fitted with pinch tap

6.2 SANITIZATION

a) Coolers

Odd numbered coolers were unsanitised. Even numbered coolers were sanitised as follows:

The cooler head was removed.

Using the CoolerClean bottle the correct dose of the chemical was introduced into the reservoir. This was at the rate of 25 ml per 1.7.litres or 0.5 gallon

The water level was topped up with water from a new bottle of Prospect Wells water (Classic's water).

The cooler interior was cleaned with a new brush or cloth (depended on degree of scaling) with the CoolerClean solution in place.

The CoolerClean solution was run briefly out of the taps and the taps closed.

The solution was left in place for 5 minutes and then drained off

b) Taps

The taps were removed from 5 machines and given a 2 second spray of CoolerClean Spray into the tap outlet. The tap mechanism was worked to ensure full coverage of components.

The chemical was left in situ for 2 minutes and the tap emptied

6.3 SAMPLING/TESTING

a) Coolers

Because of the 'destructive' nature of swab testing (you cannot swab the same area twice and get sensible results) half of the coolers were not sanitised and the others sampled only after sanitisation. Swab samples were taken from the reservoir and tap mechanisms of each machine.

All swabs were tested for total viable count at 22ºC (3 days) by the WRC/NSF Laboratories at Medmenham, Buckinghamshire UK.

7. RESULTS

7.1 Microbiological results for coolers before and after sanitisation

Table 1. Reservoirs

Cooler No.	Total Viable Count per swab @ 22ºC (3 days)
Cooler No.	Before Sanitization	After Sanitization
1	12,000,000	---
2	---	100
3	1,900,000	---
4	---	8,200
5	5,900	---
6	---	100…
7	66,000	-
8	----	300
9	13,100	---
10	---	<100
11	51,000	---
12	---	<100
13	243,000	---

Table 2. Taps

Cooler No.	Total Viable Count per swab @ 22ºC (3 days)
Cooler No.	Before Sanitization	After Sanitization
1	9,800,000	---
2	---	100
3	1,500,000	---
4	---	100
5	9,200	---
6	---	500
7	53,000	---
8	---	300
9	13,700	---
10	---	<100
11	<100	---
12	---	<100
13	100	---

7.2 Microbiological results for taps after sanitisation

Table 3. Taps

Tap no	TVC per tap @ 22°C
1	100
2	117,000
3	100
4	100
5	5,800

8. DISCUSSION

a) Cooler Trial

This trial is very similar in format to several earlier ones carried out by this consultancy using ozone, hypochlorite and peroxyacetic acid to sanitise coolers. The comments made here are based on the knowledge acquired in the earlier trials

The untreated results for both taps and reservoir sides demonstrate clearly that coolers at the end of the sanitisation cycle can carry considerable numbers of bacteria in their biofilm.

With one exception CoolerClean gave remarkable improvements in the hygienic quality of both the reservoir sides and the taps giving virtual sterility in most cases. Even with the exception the results still showed a considerable reduction.

These results are better than any other achieved in similar trials but for the reservoirs, only show only a moderate improvement over those obtained with peroxyacetic acid and ozone.

For the taps however the results are markedly superior to those obtained in any earlier trial. It must also be noted that in this case the taps were not dismantled for cleaning but left intact on the machine.

b) Tap Spray Trial One result was poor but the others gave a reasonable reduction in bacterial numbers

9 CONCLUSIONS

Thirteen coolers were allowed to become heavily soiled during three months heavy use without sanitization.

CoolerClean Rinse proved to be ideal for its intended task and gave results equal to or much better than other sanitisation methods. It was especially effective in dealing with taps as part of the full sanitisation process.

The method was effective even when not all the scale could be removed during cleaning. In this trial no chemical descaling was carried out. Descaling treatment would be normal for coolers used with a high calcium water. Exceptionally and to the author a little unexpectedly, the taps of the coolers were disinfected very effectively even though they were not dismantled for cleaning Taps are notorious as the most difficult part of a cooler to disinfect properly because of their internal complexity

The Cooler Care Spray was applied less rigorously than the Rinse thus reflecting field use. One tap was clearly heavily soiled and not dealt with effectively but in general the product was promising especially bearing in mind that it is intended for use by the customer on a much more frequent basis than every 13 weeks or as an adjunct to other sanitisation methods. This was a limited test and further tests may be warranted. It is likely to be very effective on less complex areas such as the bottle cap and the exterior of the bayonet or on less heavily soiled taps.

CoolerClean Spray is recommended as a useful addition to cooler care not least because it will encourage customers to carry out cooler care between the 13 week full sanitisations and also to treat bottles and the bayonet system with care.

CoolerClean Rinse is a very effective cooler disinfection chemical . It may need to be used after cleaning if heavy soiling or scaling is encountered but this is true of all other disinfectants. Although CoolerClean is highly effective in dealing with taps in situ it is recommended that taps still be dismantled for sanitisation when there is evidence of significant contamination with Pseudomonas aeruginosa or coliform organisms. It may also pay to dismantle taps every 2 or 3 sanitisations depending on conditions.

CoolerClean Rinse is highly recommended

M.J. Hurst

Consultant Microbiologist

Watermark Consultancy 15 September 2000