With immediate effect, new articles in this journal will be published Open Access with no publication charges. Every researcher and practitioner in every country around the world will be able to read them. This is possible because we are moving to an innovative new model called Subscribe To Open (S2O). University libraries will continue subscribing to the journal and articles from the most recent five years will be freely accessible to all. Older articles will be available at subscribing institutions and for IWA members.

Why does this matter? The world is changing rapidly. Factors such as global warming, the global COVID-19 pandemic, rapid urbanisation, industrial and agricultural advances and population growth are placing unprecedented stress on our most valuable resource: water. Today, 4 billion people use sanitation facilities that are not safely managed, at home 680 million having no sanitation facilities at all, and 2.1 billion no access to safely managed drinking water. A third of schools have inadequate water supplies (UNICEF & WHO 2019). Actions to mediate the increasing risks of floods, droughts and windstorms mean many more people may lose access to safe drinking water temporarily or permanently, and may be forced to migrate away from their home areas, placing additional stress on water and sanitation systems in other cities, towns and villages As Editors of IWA Publishing journals, we recognise the essential role that research – and the availability of the very latest research – plays in understanding the problems the world faces, and providing real-world solutions to those problems.

IWA Publishing's mission is to spread knowledge about clean drinking water, safe sanitation, water resources management policies and the latest innovations in water technology and sustainability. The best way to do this is to ensure that everyone, everywhere has access to the content published in IWA Publishing journals. Equally important is that all authors have the same potential to publish their work Open Access regardless of their geographic location or their funding situation. For this reason, we are proud to announce that all IWA Publishing journals are now Open Access and that Open Access to the following 10 journals has been made possible through the S2O model:

AQUA: Water Infrastructure, Ecosystems and Society

Journal of Hydroinformatics

Journal of Water and Climate Change

Journal of Water and Health

Journal of Water, Sanitation and Hygiene for Development

Water Policy

Water Practice and Technology

Water Quality Research Journal

Water Science and Technology

Water Supply

For European researchers, immediate Open Access means that this journal is compliant with EC funding requirements. Articles published with S2O will be Open Access and will remain that way for all time.

S2O is a collaborative Open Access model that relies on continued journal subscriptions in order to make content Open Access without the need for author fees. Journal subscriptions are seamlessly transitioned to S2O subscriptions granting subscribers not only full access to the IWA Publishing portfolio but also unlimited free publication for their authors in IWA Publishing's S2O journals. It also means that any authors seeking to publish Open Access, regardless of their affiliation can publish in IWA Publishing's S2O journals for free.

As a collaborative Open Access model, S2O depends on the continued support of the community. We are grateful to all of the institutions, organisations and individuals that have subscribed in 2021 and helped us reach our 2021 Open Access goal.

To continue to sustain and operate under this Open Access model in future years, we encourage this journal's readers and authors to let their institutions and their university libraries know about IWA Publishing and S2O. Working together, we can continue to make our journals accessible to all.

IWA Publishing Editors in Chief

Pernille Ingildsen& Shuming Liu, AQUA

Orazio Giustolisi, Journal of Hydroinformatics

D. Nagesh Kumar, Journal of Water and Climate Change

Nicholas Ashbolt, Journal of Water and Health

Barbara Evans& Guy Howard, Journal of Water, Sanitation and Hygiene for Development

Jerome Delli Priscoli, Water Policy

Peter Vanrolleghem& Arash Zamyadi, Water Quality Research Journal

Wolfgang Rauch, Water Science and Technologyand Water Practice and Technology

Slobodan Djordjevic, Water Supply

Progress on household drinking water, sanitation and hygiene, 2000–2017. Special focus on inequalities
United Nations Children's Fund (UNICEF) and World Health Organisation (WHO)
New York
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).