Closed System Testing

What is Closed System Testing?

Closed System Testing refers to testing water in a controlled environment. In closed-system testing, there are microbiological, physical and chemical analyses.

Tests include a physical inspection of the water, measuring pH levels, and analysing the concentrations of minerals such as copper, iron, calcium, magnesium, zinc, phosphates, silicates, potassium, aluminium and sodium. Echo Square specialises in closed-system water testing to support BSRIA BG 50/2013 standards.

Here are several reasons why
closed system testing is important:

Environment Control

Closed water testing allows researchers to create and maintain specific environmental conditions, such as temperature, pH levels, water chemistry, and nutrient concentrations.


Closed water testing facilitates the replication of experiments by using standardized protocols and maintaining consistent conditions.


Closed systems minimize the influence of external factors on experimental outcomes. They isolate the aquatic environment from natural disturbances.

Time Efficiency

Closed water testing can accelerate research progress by enabling faster data collection and analysis.


Closed systems can be more cost-effective than conducting field studies. They eliminate the need for extensive fieldwork, such as travel expenses, logistical challenges, and potential risks.

Microbiological Analysis

Microbiological Analysis tests for bacteria most commonly found in closed systems. If left to proliferate, this can cause serious problems.

TVC/Aerobic colony count

Nitrite Reducing Bacteria

Pseudomonas Bacteria

Sulphite Reducing Bacteria

Physical & Chemical Analysis

Evaluating water composition in enclosed systems entails assessing the concentrations of different components, such as metals and other substances, in the water.

Alkalinity as CaCO3

Aluminium (Dissolved)

Boron (Dissolved)

Ammoniacal nitrogen

Calcium (Dissolved)


Plus, much more. Other Tests can be carried out as required.

New Commissions & Water Quality Considerations

During the initial heating or cooling system charging, the tanks are typically filled with water sourced directly from the mains water supply. Consequently, the closed system will inherit the bacterial and mineral content present in the main water.

Regional variations and the specific water source influence the levels of bacteria and minerals in the closed system. Notably, the mineral composition can differ across geographical locations and water extraction points.

Furthermore, it is important to note that the expected bacterial levels in mains water can range from 10 to 100 cfu (colony-forming units) per millilitre of water.

Testing for Bacteria in Closed-systems

Various types of bacteria can be found in mains water. Although Enterobacter, Klebsiella, and Citrobacter may exist, their survival and growth within a closed system are highly unlikely.

Nevertheless, as these bacteria perish, they can serve as a nutrient source for other bacterial varieties.

Additional bacterial species that can pose problems in closed heating and cooling systems include Pseudomonas, Flavobacterium, Acinetobacter, and Aeromonas.

These bacteria generally do not proliferate to levels that cause issues in a drinking water supply.

However, in a closed system, they can rapidly produce slime and initiate the formation of biofilm on internal surfaces such as pipework, pumps, and heat exchangers.

Moreover, mains water can also contain iron, sulphite-oxidising bacteria, and sulphite-reducing bacteria.

Iron bacteria thrive on ferrous substances and can contribute to corrosion.

The presence of red, orange, or yellow-coloured water often indicates the presence of iron bacteria.

If a black slime is observed within the system, it suggests the presence of sulphite-oxidising bacteria. If an unpleasant odour accompanies the slime, the issue may involve sulphite-reducing bacteria.

This type of bacteria is highly corrosive and can cause significant damage.

Closed system testing for bacteria
Closed system testing for biofilm

Biofilm Problems

When a newly commissioned closed system is put into service, one of the initial types of bacteria to establish itself is typically the slime or biofilm-forming bacteria.

These bacteria have the capability to form layers of biofilm on surfaces, creating a conducive environment for other bacteria to grow as well.

As the bacterial population accumulates, it inevitably begins to impact the thermal efficiency and overall operation of the closed heating or cooling system.

Bacterial layers act as insulation, thereby limiting heat transfer efficiency and affecting the system’s hydrology.

If the biofilm grows unrestricted, the oxygen levels within the system gradually diminish.

Consequently, this creates an environment suitable for the growth of anaerobic bacteria, such as sulphite-reducing bacteria (SRB), which do not require oxygen to thrive.

In cases where water levels in the closed system need periodic replenishment from an open header tank, the bacterial count can be even higher.

This is attributed to the specific storage conditions of the water.

If bacteria are not adequately addressed through the use of specialized closed-system water treatment chemicals known as biocides, the entire system may eventually fail. At best, its reliability and thermal effectiveness will be compromised.

Need help with Closed System Testing?

Echo Square are qualified in BSRIA closed system testing in water tanks. If you need support or advice with this particular service, then please do get in touch. Our services are based throughout the United Kingdom.

Who We've Worked With

James Eckloff
James Eckloff
We used Echo Square services to reline a water tank in a local school recently, fantastic work and completed within the timescales needed
Gaetano milazzo
Gaetano milazzo
Had a cold water tank in the loft full of dust, wasp and flies. Tanks were cleaned to a very good standard, considering the awkwardness of the job. Very happy with the service
Stuart Mills
Stuart Mills
We were carrying out plumbing works on a site in London where we discovered a badly leaking GRP water tank, the Echo Square Services team attended site as quickly as possible to repair the leak and reline the tank. We will definitely contact them next time we are faced with a similar issue - would highly recommend.
Daniel Sheen
Daniel Sheen
We had a heavily leaking metal water tank above our office which was leaking through our ceiling, Echo Square Services repaired the leak and relined the tank just two days after we made the enquiry!
Harold Carter
Harold Carter
Arrived very quickly when the crisis developed in the 100-year-old water tanks in this Grade 1 listed building; did what looks a highly professional job (re-lining two hard to get at tanks in the roof) all in one day - which involved working really late - and were careful to make no mess and cause no damage. So far, it looks a great job at a reasonable cost.
Stuart Mills
Stuart Mills
I have used Nationwide Tank Relining on two occasions now and each time I have been absolutely delighted with their service, ‘can do’ attitude and professionalism from start to finish. I will definitely be requesting their services again in the future.
Luke Busby
Luke Busby
Working with James was a pleasure, thanks again bud will be in touch for my next project
I contacted ECHOSquare to reline our water tank due to it being damaged and developing a leak, we needed the job doing ASAP as our site had no water so staff had to be sent home until it was fixed, James understood how urgent the job was and he was i spoke with him on the Friday and he was able to get the job booked in for the Monday, all The necessary Paper work, IE Rams & Training Certificates were sent to me via email before the guys got to site, from start to finish the service was excellent, Thanks ECHOSquare.
Dark Iron Fabrications
Dark Iron Fabrications
The team was very helpful, polite and knowledgeable. Glad to speak to people who know what they're doing. Won't hesitate to use them again in the future
Rachel Pickett
Rachel Pickett
Having used other companies in the past I can wholeheartedly say that our dealings with Nationwide Tank Relining have been a breath of fresh air. We have had tanks relined, water hygiene assessments and floor coatings. All work was carried out in a timely manner and the quality of work has each and every time been exemplary. My bosses are thrilled with my decision to switch to Nationwide Tank Relining and a tank that was relined 10 years ago by them still looks good as new internally, and the money we've saved from choosing the right supplier has proven to be a very smart business move. Highly recommended!

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You can rest assured that Echo Square will provide the very best service from start to finish and emergency backup should you ever need it.

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