Wastewater testing for SARS-CoV-2
Real time, quantitative Polymerase Chain Reaction testing for the virus responsible for COVID-19
Current studies indicate that remnants of SARS-CoV-2 virus are present in wastewater, suggesting wastewater as a marker to:
- Measure the prevalence of COVID-19 in communities
- Anticipate outbreaks
- Warn of future outbreaks
The ALS wastewater testing method to detect SARS-CoV-2:
- Detects and confirms SARS-CoV-2 by targeting two genome sequences in accordance with WHO recommendations.
- Regular and on-going monitoring of wastewater effluent can provide an early indication of SARS-CoV-2 outbreak in populations, possibly while occupants are asymptomatic but potentially contagious. Testing can provide trend data indicative of viral load over time.
This testing is intended for Institutions or companies where populations reside or conduct businesses such as:
- Government bodies including federal, state and municipal offices.
- Production sites, businesses, hospitals, nursing homes, prisons, schools and universities, military bases.
Composite sampling is recommended
A time-weighted composite sample requires the collection of multiple sample aliquots of equal volume collected at a consistent time interval over a specific period of time. Composite sampling is more reliable because it is representative of the waste stream over time.
A flow-weighted composite sample is the most reliable and the preferred method of composite sampling because it is collected over time and it is proportioned based on flow volume. When flow-weighted composite sampling is performed, many more sample aliquots are collected when the discharge is flowing at 200 gallons per minute as opposed to when only 10 gallons per minute are being discharged. This sampling method results in a more representative composite sample as compared to a time-weighted sample.
Where to sample
It may be necessary to review construction drawings or engage a consultant to determine optimal location(s) and testing frequency. Accessibility, security, and power availability (although most auto-samplers can run on 12V batteries) should also be considered.
Wastewater should be collected using a composite autosampler over a time period representative of the population profile (e.g.: 100 ml sample draw per hour over 24 hours). Collection can be either flow-proportional or time-dependent (e.g.: a 24-hour operation should be sampled over a 24-hour period. A site that operates for only 8 or 16 hours should sample during those hours only.) The sample is called a composite sample because it is made up of many individual subsamples taken over time. The sample to be sent to the lab is subsampled from the composite sample into the supplied 250 ml bottle.
Once subsampled into a 250 ml plastic bottle, samples should be chilled and expedited to the laboratory within 72 hours using the provided package with ice or ice packs.
Packaging must maintain 2-8°C and the samples must arrive in the laboratory within 72 hours from sampling. For international orders, please contact the ALS laboratory in your country as this service is available worldwide.
- Test results are reported qualitatively as Detect or Not Detect along with the semi-quantitative cycle threshold (Ct) score that can be used to indicate change in viral load over time. This Ct score ranges from 6.25 to 250 copies per mL.
Sample cooler kit
ALS provides kits for in-house (self) sampling upon request that includes:
- 250 ml plastic sample container(s)
- Sample label(s)
- Chain of custody
- 2 plastic zipper bags for each sample container
- Absorbent pad(s) for each sample container
- Shipping box or cooler (use for return shipping)
Note: Packaging and shipping are available upon request and not included in testing costs.
Currently testing wastewater for normal regulatory requirements with ALS?
Packaging and shipping can be combined. Contact your designated ALS Project Manager for placing orders or for other clarifications.
Sampling frequency should be based on monitoring objectives and risk profile. Daily composite samples are recommended.
Factors to consider when determining test frequency include:
Local community viral spread statistics –
- Severe: sampling 3x/week
- Significant: sampling 2x/week
- Moderate: sampling 1x/week
- Normal: sampling 1x/every two weeks
Sampling point(s) should be prior to treatment and selected such that they capture the wastewater outflow from the population to be monitored.
- wastewater line cleanout ports
- manholes just prior to city/municipal sewer lines
- influent points to a wastewater treatment plant