Table 1.

Information on the sampling, storage/transport conditions and sample pre-treatment used for the detection of SARS-CoV-2 RNA in wastewater.

Reference The papers marked with an asterisk (*) were not certified by peer review (preprints)	Location given in alphabetical order	Information on UWTPs (Inhabitant/Population Equivalents, treatment, etc.)	Dates of sampling	Type of sample	Type of sampling container	Freezing and transfer of samples	Storage conditions at the laboratory	Days to analysis	Thermal sample treatment
[34]	Australia	Suburban pumping station and 2 UWTPs of urban catchments in Southeast Queensland	March-April 2020	collection of untreated wastewater (grab samples) using conventional refrigerated autosampler or a submersible high frequency autosampler	not reported	transfer on ice	storage at 4 °C	not reported	×
[35]	Australia	UWTP in Brisbane, Australia (PE = 325000) urban and industrial wastewater; primary treatment, CAS, and disinfection with chlorine and UV	not reported	2 L of untreated wastewater	not reported	transfer on ice	storage at 4 °C	24 h	×
[4]	Australia	Cruise ship and 3 aircrafts	Cruise ship: 23/4/2020 Aircrafts: 1)26/4/2020 (117 passengers) 2)7/5/2020 (19 passengers) 3)10/5/2020 (185 passengers)	Cruise ship: two grab samples from influent and effluent of MBR of the ship Aircrafts: three grab wastewater samples from each aircraft	not reported	Maintenance at 4 °C for transport	Maintenance at 4 °C for transport	6-24 hours	×
[7]*	Brazil	UWTP in Florianopolis, Santa Catalina, Brazil (serving 5000 inhabitants) Raw sewage	30th October 2019 to 4th of March 2020	200 mL of urban sewage	not reported	not reported	storage at 80 °C	not reported	×
[25]*	France	Influent wastewater of UWTP in Montpellier metropolitan area in Lattes	May 7th, 18th, 26th and June 4th, 15th and 25th 2020	Composite samples	not reported	Maintenance at 4 °C for transport	Centrifugation at 4500xg for 30 min at 4 °C andsieving of supernatant through 40 μm Corning strainer followed by storage at -20 °C	Samples were processed immediately upon arrival in the laboratory	×
[6]*	France	3 UWTPs (>100000 IE) in Paris	5th of March 2020 (start of the epidemic) - 23th of April, 2020.	not available	not reported	not reported	storage at 4 °C	Samples were processed in less than 24 h after sampling	×
[32]*	India	UWTP in Ahmedabad, Gujarat (106 million L/day) Upflow Anaerobic Sludge Blanket (UASB); receives the wastewater from a governmental hospital treating COVID-19 patients	8th and 27th of May, 2020	influent and treated effluents (after UASB and aeration pond)	sterilized bottles	transfer on ice	refrigeration of the samples taken on the 8th of May at 4 °C till the 27th of May when next batch of samples were transported to the laboratory and analysed immediately	not reported	×
[27]*	Israel	11 UWTPs in Haifa, Shafdan, Rahat, Arara, Beer Sheva, Ayalon, Zfat, El Hamra, Kidron, Sorek, Og	10th March, 25th March, 30th March, 3rd April, 5th April, 13th April, 15th April, 16th April, 21th April, 2020	collection of 200 mL of sample every 30 min for 24 hours	not reported	transfer of 6-10 L of sample to the laboratory, with transfer of 2 L samples to clean plastic bottles	storage at -20 °C or−80 °C.	not reported	×
[22]	Italy	3 UWTPs in Milan (Plant A and B; PE = 1.050.000) and Rome (Plant C1 and C2; PE = 900.000)	3rd of February - 2nd of April, 2020	24-h composite raw wastewater samples	not reported	not reported	storage at -20 °C	not reported	√ 56 °C, 30 min
[24]*	Italy	5 UWTPs in Milan (Plants A and B; PE = 1116928 and 750863, respectively), Turin (Plants C and D; PE = 2297000 and 180000, respectively) and Bologna (Plant E; PE = 653809)	9th of October 2019 – 28th of February 2020	24-h composite raw wastewater samples		not reported	storage at -20 °C	not reported	√ 56 °C, 30 min
[9]*	Italy	3 UWTPs (UWTP-A in Monza/Brianza; UWTP-B and C in Milano); flow = 11 m3/s, IE = 2 million secondary treatment; tertiary disinfection by peracetic acid or high intensity UV disinfection. UWTP-A and UWTP-B disposal into the Lambro River, and UWTP-C into the Lambro Meridionale River	14th and 22th April, 2020	grab wastewater and river water samples (at 1.00 p.m.)	polypropylene bottles for wastewater, dark glass bottles for river water	transfer of samples under refrigeration	not reported	not reported	×
[33]*	Japan	UWTP and river in Yamanashi Prefecture CAS	17th of March-7th of May, 2020	collection of samples from influent and secondary-treated wastewater before chlorination and river water samples	1-L sterilized plastic bottles	transfer on ice	not reported	6 h after sampling	×
[26]	Spain	6 UWTPs in Murcia (PE = 530499; CAS, disinfection [NaClO]), Cartagena (PE = 163969; CAS, disinfection), Molina de Segura (PE = 150545; CAS, coagulation, flocculation, sand filtration, disinfection [UV, NaClO]), Lorca (PE = 101161; CAS, coagulation, flocculation, sand filtration, disinfection [UV, NaOCl]), Cieza (PE = 69502; CAS, coagulation, flocculation, sand filtration, disinfection [UV]), Totana (PE = 28289; CAS, disinfection [UV])	12th March - 14th April, 2020	grab samples (at 7-12 am) 42 influent, 18 secondary and 12 tertiary treated effluent samples	HDPE plastic containers	transfer of samples on ice to the laboratory.	storage at 4 °C	24 h	×
[21]* [38]	The Netherlands	UWTPs in Amsterdam (IE = 1014000), Hague, Utrecht (IE = 530000), Apeldoorn (IE = 350000), Amersfoort (IE = 335000), Tilburg (IE = 375000), Schiphol airport (IE = 54000)	5th, 6th and 7th of February, 2020 (3 weeks before the first reported COVID-19 case in the Netherlands), 4th and 5th March, 2020 (38 and 82 reported COVID-19 cases, resp.), 15th, 16th and 25th of March, 2020 (1135, 1413, and 6412 reported COVID-19 cases, resp.)	24 h flow-dependent composite wastewater sample (250 mL)	not reported	freezing of samples at 4 °C andtransfer on melting ice	not reported	not reported	×
[28]*	Turkey	7 UWTPs in Istanbul, Turkey and 2 manholes nearby Istanbul hospitals Preliminary treatment; CAS; advanced nutrient removal	21st and 25th of April, 2020	grab samples	250-mL sterilized bottles	not reported	not reported	not reported	×
[29]*	USA	11 points of sampling (i.e., 6 wastewater treatment plants, and 5 inlet pumping stations, or interceptor lines) in Syracuse, NY and other locations in Onondaga County, NY. PE = 12800-223900 (UWTPs) PE = 3841-112747 (interceptor lines)	6th and 13th May, 2020	24 hour-composite wastewater samples	not reported	storage of samples at 4 °C andtransportation on ice to Upstate Medical University (Syracuse, NY)	not reported	Next morning	×
[8]*	USA	UWTP in Bozeman, Montana	18th-25th of May, 2020	Collection of 0.5-L samples of pre-treated wastewater on 7 days within a 17-day period, using two collection methods (grab and 24 h-composite samples)	not reported	not reported	not reported	not reported	×
[30]	USA	9 composite and 6 grab wastewater samples from two UWTPs in Southern Louisiana, respectively (UWTP A = 244627 PE; UWTP B = 45694 PE) 7 raw wastewater samples 4 secondary treated samples 4 final effluent samples after chlorination	January 13th 2020 February 3rd 2020 March 2nd 2020, April 8th and April 29th 2020	not reported	Sterile 1 L Nalgene bottles	Transport on ice to the laboratory	not reported	not reported	×
[31]*	USA	UWTP in Massachusetts	18th March-25th of March, 2020	24 hour-composite samples of raw sewage	not reported	not reported	storage at 4 °C	not reported	√ 60 °C, 90 min

Abbreviations (given in alphabetical order): CAS: Conventional Activated Sludge; IE: Inhabitant Equivalent; PE: Population Equivalent; UASB: Upflow Anaerobic Sludge Blanket