Potable water—water that is safe for human consumption—is a vital component of public health infrastructure. Ensuring its quality is not only a regulatory requirement in many regions but also a fundamental aspect of protecting the health and wellbeing of building occupants. One critical but sometimes overlooked area in maintaining potable water safety is the regular sampling of water from cold water storage tanks.

Why Cold Water Storage Tanks Require Monitoring

Cold water storage tanks are commonly used in residential, commercial, and industrial buildings to ensure a consistent supply of water. Over time, these tanks can become sites for microbial growth, sediment accumulation, and temperature fluctuations, all of which can impact water quality. If not properly maintained and monitored, these tanks may become a breeding ground for harmful bacteria such as Legionella, which can cause Legionnaires’ disease—a serious form of pneumonia and other potentially harmful waterborne bacterium such as E.Coli.

Key Reasons for Sampling

1. Detection of Contaminants
   Regular sampling helps in identifying microbiological and physical contaminants that may enter the tank through backflow, poor maintenance, or environmental factors. These contaminants can pose serious health risks if ingested or inhaled in aerosol form.
2. Compliance with Health and Safety Regulations
   Many countries like the UK have regulations that mandate routine testing of water systems, especially in facilities like hospitals and care homes. Failure to comply can result in legal action, fines, or even shutdowns of facilities.
3. Prevention of Waterborne Diseases
   Cold water storage tanks that are not properly maintained or monitored can support the growth of bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Legionella. Sampling helps in early detection and prevention of outbreaks.
4. Verification of Maintenance Procedures
   Sampling provides tangible data to verify the effectiveness of cleaning and disinfection procedures. If issues persist, the data can guide improvements in water management protocols.
5. Trend Analysis Over Time
   Consistent sampling allows for the tracking of water quality trends. This can help in identifying seasonal variations or gradual declines in water quality that may require long-term corrective actions.

How Sampling Is Conducted

Water sampling from cold water storage tanks should follow established guidelines and use sterile techniques to avoid contamination. Samples are typically taken from different points within the system, including the tank itself and the outlets it serves. Temperature, and microbial presence are commonly measured parameters. It is essential that trained personnel conduct the sampling to ensure accuracy and reliability.

Conclusion

Regular potable water sampling from cold water storage tanks is a proactive approach to maintaining water quality and safeguarding public health. It supports regulatory compliance, helps detect potential problems early, and ensures the water supplied remains safe for consumption. In the broader context of water hygiene management, routine sampling is not just a best practice—it is a necessity.

GMS recommends that cold water storage tanks that supply drinking water should be sampled (drinking water suite) on a quarterly basis and in adherence to BS8554: 2015 or BS 7592: 2022 for Legionella on a 6-monthly basis and dependant on risk. Your risk assessment should provide more information round sampling requirements.