Sterile Filtration: High-Quality Water for Medical Facilities

The requirements for sterile filtered water go beyond those for standard drinking water hygiene. Sterile filtration water is of exceptionally high purity and is primarily used in medical facilities and medical manufacturing. This water is manually filtered to ensure sterility.

According to the U.S. Food and Drug Administration (FDA), sterile filtration achieves a log 7 reduction (99.99999%) of Brevundimonas diminuta, the smallest known waterborne bacterium. More details can be found in our article: “Log reduction and filter validation according to ASTM F838”

Contents

• Inline filtration
• Sterile water filters in manufacturing
• Benefits of sterile water filters
• Recommendations for the use of sterile water filters

Sterile filters against Legionella, Amoebae, and other microorganisms

Water utilities in most European countries, including the UK, supply highly regulated water that meets drinking water hygiene standards. However, contamination can still occur within building plumbing systems.

Causes of contamination include:

• Narrow pipes and complex plumbing layouts, reducing flow rates
• Dead legs, leading to stagnation water
• Increased water temperature in certain pipeline sections

If water remains unused for an extended period, it is referred to as stagnation water.

Stagnation water provides ideal conditions for biofilm formation, which can contain bacteria, amoebae, algae, and other microorganisms. Within biofilms, pathogens such as Legionella or Pseudomonas find ideal conditions to multiply, posing a high infection risk for immunocompromised patients.

To protect these high-risk individuals, hospitals use sterile filtered water, ensuring patient safety during treatments.

Point-of-use filtration and inline filters for greater efficiency

Hospitals and other medical facilities in the UK rely on both point-of-use filtration and inline filtration systems.

• Point-of-use filtration: Sterile water filters are installed directly at water outlets (e.g., taps, showers), ensuring that water is sterile filtered at the point of use.
• Inline filtration: These filters are integrated within the plumbing system, protecting the entire water supply infrastructure.

Sterile point-of-use filters typically use membrane technology with a pore size of 0.2 µm, effectively removing bacteria and other pathogens. These filters must withstand temperatures up to 60°C and pressures up to 5 bar, as required in hospital water systems. Importantly, sterile filtration does not alter the chemical composition of the water.

Sterile filtration in clinical water supply systems

In some clinical settings, inline filters installed within the plumbing system provide additional protection.

Key applications include:

• Endoscopy reprocessing: Inline sterile filtration prevents recontamination during the final rinse cycle in endoscope washer-disinfectors (EWDs).
• Water supply for birthing pools and dental chairs: Hollow-fibre membrane filters provide additional safety.

Sterile water filters in manufacturing

Sterile water filters are produced and packaged under cleanroom conditions. For certain applications, sterilised sterile water filters are required.

These filters undergo gamma sterilisation (Cobalt-60 radiation) after production and packaging, ensuring absolute sterility. Sterilised sterile water filters typically have a two-year shelf life, making them reliable for long-term storage.

Benefits of sterile water filters

The quick and simple installation of sterile water filters makes them an effective infection control measure in healthcare settings.

• Flexible installation at taps or showers
• Reliable pathogen retention for the entire usage period
• Available as disposable or reusable filters, depending on the manufacturer
• Some models feature antimicrobial coatings for additional protection against contamination

Use of Water Filters in Non-Medical Settings

Outside medical settings, sterile filtration water is commonly used in response to Legionella contamination. Sterile water filters help prevent:

• Shower bans in residential buildings
• Temporary closures of sports and swimming facilities
• Legionella outbreaks in seasonal hotels and holiday resorts

By using point-of-use sterile filters, these facilities can ensure safe water quality without disrupting operations.

Guidelines on sterile filtration in hospitals

The World Health Organization (WHO) recommends point-of-use sterile water filtration as an infection prevention measure for high-risk hospital areas.

In the UK, Health Technical Memorandum 04-01 (HTM 04-01) provides official guidance on managing hospital water hygiene, including the use of point-of-use sterile water filters to prevent the spread of waterborne pathogens.

According to NHS England (HTM 04-01), sterile water filters should be used in:

• Intensive care units (ICUs)
• Oncology and transplant wards
• Neonatal and maternity wards
• Endoscope reprocessing units

Additionally, the MHRA (Medicines and Healthcare products Regulatory Agency) provides guidance on the regulatory classification of point-of-use hospital water filters in the UK. Official NHS HTM 04-01 Guidelines: Health Technical Memorandum (HTM 04-01) – Safe Water in Healthcare Facilities. 

MHRA Regulatory Guidance on Water Filters: UK Government Guidance on Hospital Water.

Filters Sterile Filtration in Hospitals: Proven in Clinical Practice

Sterile filtered water is a cost-effective and sustainable infection prevention measure in hospitals and healthcare facilities.

• Unlimited use for daily hygiene in hospitals
• Safe wound irrigation and medical cleaning
• Significant reduction in hospital-acquired infections

As infection prevention becomes increasingly important in healthcare, more hospitals are adopting sterile water filtration to ensure better patient safety.

For more details check out our article on different types of water filtration!