CDC's Wastewater Monitoring Program Data Methodology

Ensuring high-quality data

CDC receives data from over 1,000 wastewater monitoring sites across the United States each week. CDC's wastewater monitoring program recommends that each site conducts wastewater testing twice per week. CDC's experts work hard to ensure these data are of high quality, comparable across sites, and understandable.

Protecting data quality

Before publishing updated wastewater data, CDC completes data quality checks and reviews the data to ensure there aren't any issues.

Increasing understanding of data

CDC works with state, tribal, local, and territorial health departments to ensure that metrics and visualizations are easy to understand and use for public health, clinical, and individual decision-making.

Continuous improvement

Wastewater monitoring is an evolving science, and CDC may update methods and visualizations to improve how wastewater data are shared.

Public data display policies

CDC will not publicly display any wastewater detections that could be used in combination with clinical diagnostic testing data to identify an individual. Locations for wastewater treatment plants are approximated. Locations may also be adjusted to make nearby sites easier to distinguish on the map. CDC does not display data from wastewater monitoring sites that have known data quality issues.

In addition, CDC does not publicly display data that meet any of the following criteria, unless approved by the local jurisdiction:

• Data from sewersheds that serve fewer than 3,000 people
• Data from facility or institution-specific sampling locations
• Data from tribal communities

How CDC protects privacy

Wastewater samples contain a mix of DNA and RNA from bacteria, viruses, animals, humans, and other living things. CDC's wastewater program monitors infectious diseases and does not track or assess human genomic data.

CDC takes multiple steps to protect the privacy of individuals through legal requirements, technical safeguards, policies, and procedures.

CDC does not collect data from individuals

Wastewater is collected from a combined, community-level sample, not from an individual person or household. Sampling covers a large enough population that wastewater testing results for infectious diseases are not associated with an individual person.

Every person has their own unique genome, or DNA "fingerprint." To identify an individual, one would need to match the DNA fragments from wastewater to their DNA fingerprint. Although there is a small, theoretical chance this could happen, it is highly unlikely. CDC does not have individuals' DNA fingerprints and therefore cannot match DNA fragments found in wastewater to individuals.

CDC uses data privacy technology

Sequencing data can accidentally include small bits of human DNA or RNA, called human reads, mixed in with the pathogen data. To protect privacy, these human reads are removed through a process called human read scrubbing before the data are used. CDC analyzes wastewater sequencing data deposited into NCBI, and uses a tool from NCBI to scrub any human reads the sender hasn't already removed.

CDC is preparing for the future

CDC will continue to preserve individual privacy and prioritize data stewardship as technology evolves, including updating policies if technologies emerge that enable individual identification using wastewater data.

CDC will follow ethical standards in wastewater science to protect individual privacy and improve public health. CDC will work with participating communities to understand ongoing priorities and concerns.

GitHub data repository

CDC's wastewater program hosts a GitHub data repository to support collaboration and to share code among jurisdictions, CDC, and the public to advance wastewater monitoring activities. The repository hosts jurisdiction-contributed projects, shared tools, and supporting resources intended to promote transparency, reproducibility, and innovation in public health monitoring. All content is publicly available and maintained in accordance with CDC open-source and privacy standards.