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The Importance of Building System Cleaning and Disinfection – Hospitality

Tank cleaning and disinfection: Legionnaires’ disease, a potentially fatal form of pneumonia caused by Legionella bacteria, first gained notoriety in 1976 following an American Legion Conference in Philadelphia. Since then, it has remained a significant public health concern, particularly in buildings with intricate water systems. Legionella bacteria thrive in water sources, especially when conditions allow for their growth and dissemination. While Legionnaires’ disease cannot be transmitted from person to person, it poses a serious threat, especially to high-risk groups such as males over 45 years old, heavy smokers, alcoholics, and individuals with weakened immune systems or underlying health conditions like kidney disease or cancer.

Statistics suggest that Legionnaires’ disease affects thousands annually, with a significant portion linked to contaminated building water systems. Understanding the causation chain is crucial: Legionella must infiltrate a water system, proliferate under favourable conditions, disseminate in aerosol form, and ultimately be inhaled by susceptible individuals. Factors such as nutrient availability, temperature, and time play critical roles in facilitating Legionella growth and dissemination.

To mitigate the risk, effective cleaning and disinfection of hot and cold water systems are paramount. The Health and Safety Executive (HSG 274 p42) recommends controlling Legionella growth by keeping water systems clean and free from contaminants and corrosion, which can serve as nutrient sources for bacteria. Routine inspections and cleaning of water tanks become imperative, especially upon detecting debris or contamination, to ensure the health and safety of building occupants.

Different water systems require different approaches. Gravity tank-fed systems, frequent in commercial properties, often employ Glass Reinforced Plastic (GRP) tanks. These tanks, while durable, may deteriorate over time, manifesting issues like stress cracking or rusty bolts. Thorough inspection and maintenance protocols become essential in preserving the integrity of these systems.

Cleaning and disinfection methods vary, with chemical disinfection being a primary recommendation. Pre-disinfection may be warranted in certain scenarios, such as the presence of contaminants like dead organisms or pigeon excrement in the tank. Ensuring the thorough distribution of disinfectant to all outlets within the system, including showers and taps, is paramount to achieve comprehensive disinfection and mitigate risks effectively.

Understanding when to clean and disinfect tanks is equally crucial. Regular monitoring and risk assessments should prompt cleaning if the tank contains debris, sludge, scale, or traces of vermin. Tanks storing drinking water should undergo annual cleaning, and any alterations to the tank or pipework systems should prompt thorough disinfection to prevent contamination. Refer to page 26 of the HSG274 for easy to follow guidance

Understanding the Varieties Found Within Buildings

Within the intricate framework of building infrastructure, water systems play a pivotal role in ensuring the smooth functioning of various operations. Understanding the diverse types of water systems found within buildings is crucial for effective maintenance and management.

Systems Fed Directly from the Mains:

These systems draw water directly from the public water supply, providing a convenient and reliable source of water for building occupants.

Gravity Tank-Fed Systems:

Gravity tank-fed systems involve tanks positioned above the outlets, typically located in attic spaces or dedicated tank rooms on the roof. In tall buildings or areas with insufficient mains pressure, gravity tanks ensure a steady flow of water by utilizing gravity to create pressure. Boosted water systems, which employ pumps to strengthen water pressure, are a common feature in gravity tank-fed setups.

GRP Tanks – Glass Reinforced Plastic:

Among the most frequent types of tanks found in commercial properties, GRP tanks boast durability and versatility.

Despite their durability, sectional GRP tanks may develop leaks after being drained and refilled. This occurs due to the water pressure inside the tank, which pushes the seals together. Leaks typically manifest at the mating face between the walls and base panels, requiring prompt attention to prevent water wastage and potential damage.

Managing Tank Deterioration:

Stress Cracking:

An increasing issue observed in Glass Reinforced Plastic (GRP) tanks is stress cracking. These cracks typically manifest internally on the lip of panels and signal the end of the tank’s life cycle. Stress cracking compromises the structural integrity of the tank, leading to potential leaks upon refilling. While tank lining may temporarily address small leaks, the ultimate solution lies in tank replacement to prevent further damage and ensure long-term reliability.

Rusty Bolts:

Rusty bolts within GRP tanks often indicate underlying issues stemming from incorrect installation practices or exposure to disinfectants like chlorine. Incorrect bolt usage, where galvanized bolts intended for dry external flanges are mistakenly used for wetted surfaces, can accelerate rust formation. Additionally, chlorine exposure during disinfection processes can rapidly corrode stainless steel bolts. Thorough rinsing of surfaces above the water line post-disinfection is crucial to mitigate corrosion risks.

Capacity and Design:

Understanding the capacity and design of tanks is fundamental for maintenance personnel. Generic terms like “50-gallon tanks” denote common domestic plastic tanks, which come in various designs, some easier to clean than others. Poorly fitting lids and insulation can exacerbate issues like airlocks, affecting the tank’s functionality. Ensuring accurate measurement of tank capacity and awareness of design nuances are crucial for effective maintenance planning and execution.

At Dantek, we specialize in all Legionella control services, including tank cleaning and disinfection tailored to the hospitality industry. For further inquiries or assistance, please don’t hesitate to contact our sales team at 01454 417920 or via email at





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