The high scientific standards maintained by H2Open Journal, in their papers owe much to the continuing dedication of the journals’ reviewers, who give freely of their time and expertise. IWA Publishing is pleased to pay tribute to this contribution by recognizing those who have participated in the review process. Thus, the Editor in Chief, Editors and Associate Editors acknowledge with particular gratitude the following reviewers who have reviewed papers during the period January 2020–December 2020.
| Vasan A | Mario Cerroni | Rajitha K | Manjusree P |
| Aminuddin Ab Ghani | Ramananda Chakrabarti | Ilunga Kamika | Manali Pal |
| Ali Abbasi | Jabez Christopher | Shinobu Kazama | Dillip Panda |
| Pamela Abbott | Ian Corbin | Syed Najam Khurshid | Miguel Angel Pardo Picazo |
| Mansoor Ahammed | Regulwar D G | D Nagesh Kumar | Alison Parker |
| Marcos Airton de Sousa Freitas | Katharine Dahm | Pierre Le-Clech | Sonali Pattananayak |
| Ryan Albert | Abdelkrim Dahmen | Yanjin Liu | Athit Phetrak |
| Alla Aleksanyan | Sruthi Dasika | Jean-Luc Loizeau | M Anjaneya Prasad |
| Adel Al-Gheethi | Mawuli Dzakpasu | Stefano Longo | Ponnalagu R N |
| R Arunkumar | Francesco Fatone | Janga Reddy M. | Juan Rodríguez Sánchez |
| Vladan Babovic | Eva Fenrich | Maritza Macias-Corral | Adarsh S |
| Charlie Bacon | Andrei-Mugur Georgescu | Rajib Maity | D.A. Sachindra |
| Aminuddin Baki | Farshid Ghanbari | Rajib Maity | Pedro Simoes |
| Andrew Bastable | Fabio Gonçalves | Mohammed Matouq | Surya Singh |
| Dr. Paul Baumgardner | Jan Gregor | Fanlin Meng | Maria Theresa |
| Rolf Baur | Neil Grigg | Somnath Mondal | Thi Viet Ha Tran |
| Kalyan Bhar | Shervin Hashemi | Sylvia Mudau | Mohammad Valipour |
| Basudev Biswal | Takashi Hashimoto | Sourav Mukherjee | Peter van Thienen |
| Adrian Bonilla-Petriciolet | Hector Hernandez | Mohammad Najafzadeh | Murari Varma |
| Krzysztof Boryczko | Xiao Huang | Umamahesh Nanduri | Prashanth Vooka |
| Luis Alberto Bravo-Inclán | Indu J | Pravin Nemade | Xu Wang |
| Paul Brown | Anmala Jagadeesh | Susana Neto | Malgorzata Wojtkowska |
| Laura Bulgariu | Shuh-Ren Jing | Isaac Kwesi Nooni | Jie Yuan |