Hospital Water Tank Cleaning and Legionella Control in a Water Management Plan

A hospital never closes its doors, and its patients are more vulnerable than any other water user. A patient in intensive care, or one receiving treatment that weakens immunity, can be harmed by bacteria that do not affect a healthy person. That is why hospital water tank cleaning is not treated as routine maintenance but as part of an integrated programme for managing water inside the facility.

In this guide we explain what makes healthcare facilities different: how a tank is cleaned without cutting the water, who must take part in the decision, and where cleaning sits within a Legionella control plan. The general technical procedure for cleaning and disinfecting a tank is on our tank cleaning service page.

Why are healthcare facility tanks different from others?

• Continuous operation: operating theatres, central sterilisation, laboratories and inpatient wards need water every hour.
• More vulnerable patients: the elderly, people with chronic disease and those with weak immunity.
• Complex networks: multiple tanks, central hot water systems and long pipe runs where water can stagnate.
• Rarely used wings: closed rooms or wings under renovation whose taps go unused for days.
• Water-using equipment: sterilisers, therapeutic bathing units and some humidifiers.

The WHO fact sheet on legionellosis explains that Legionella bacteria live and grow in water systems between 20 and 50 degrees Celsius, with an optimum near 35 degrees. Among prevention measures it lists keeping hot water above 50 degrees and cold water below 20, and flushing unused taps weekly to reduce stagnation. In the hot Saudi climate it is hard to keep cold water below 20 degrees in rooftop tanks in summer, which makes cleanliness and turnover even more important.

Where does tank cleaning fit in a water management plan?

The US Centers for Disease Control and Prevention (CDC) states that health regulators there require, and the centres recommend, that certain healthcare facilities, including hospitals and long-term care facilities, have a water management programme. The CDC summarises the steps of building a programme in seven stages, and periodic tank cleaning is one of the control measures inside it.

How do you clean hospital tanks without cutting the water?

The core principle is redundancy: a tank serving critical departments is never cleaned until a backup source is confirmed to cover them for the whole duration of the work. Well-designed hospitals have tanks divided into compartments, or several tanks, for exactly this purpose.

1. 1

   Assess the risks before work

   The infection control and engineering teams review which departments each tank feeds, identify the critical ones and choose the best time for the work.

2. 2

   Switch supply to the backup compartment

   The valves of the compartment to be cleaned are closed once the other has been confirmed sufficient for demand, or an approved temporary source is arranged.

3. 3

   Isolate the work area

   Areas near dust and spray are protected, and patients and visitors are kept away from tank openings.

4. 4

   Clean and disinfect

   Following the procedure approved in the facility's plan, with safe confined-space entry and an attendant outside the tank.

5. 5

   Rinse and sample

   The compartment is rinsed, and the samples or measurements the plan specifies are taken before it returns to service.

6. 6

   Return to service and document

   Valves are opened gradually, everything is recorded in the water management programme file, and the process is repeated for the other compartment.

Also watch for closed wings or those undergoing renovation. Water stagnates in their pipes for weeks, and when they reopen that water reaches patients first. Include in the plan the flushing of taps and showers in these wings before they restart, and tie its timing to the cleaning of the tank that feeds them if the closure was long.

Clinics and small health centres: what is different?

Medical complexes, dental clinics and small health centres often do not operate around the clock, and many sit in converted commercial or residential buildings served by a shared tank. That gives them flexibility on timing, since cleaning can happen on the weekly closing day or after hours, but it adds a question of responsibility: does the tank belong to the centre or to the building?

In dental clinics in particular, the water lines inside treatment units have cleaning and disinfection instructions set by the unit's manufacturer, separate from tank cleaning. Likewise, dialysis units rely on an independent water treatment system with its own standards, handled by specialists, and cleaning the tank does not replace it.

What should be required of the contractor in a healthcare facility?

Rooftop tanks exposed to the sun raise the temperature of cold water, which is the opposite of what the WHO advises. Shading them or thermal insulation of tanks helps keep the water cooler. You can also read our health and safety page for more general guidance. A facility can request an inspection through Azl to study its tanks and prepare a work plan that suits its departments.