The market operator for the water retail market in England.

As market operator, our role now is to make sure this young market continues to grow and flourish. We make it possible for new companies to enter the market, ensuring that they can do business easily and at a low cost. When customers choose to change suppliers, we enable the transactions in our central IT system, ensuring that smooth settlement and payments take place between the wholesalers and retailers.

From our central position, we also play a key role in driving performance in the market to ensure that we, and water companies, the wholesalers and retailers who operate in the market, are held to account for our performance and ultimately deliver better services and outcomes for customers.

Our primary objective is to make the market an easier place to do business in, delivering our services to members seamlessly and effectively and making sure this vibrant young market is one that delivers on its commitment to customers for great cost, time and efficiency savings.

Who we are

MOSL is responsible for the smooth and efficient running of the non-household water market in England, which opened on 1 April 2017, allowing over 1.2 million business customers including public sector bodies, charities and not-for-profit organisations in England to choose who supplies their retail water and wastewater services.

Prior to the market opening, we played a key role in the preparations to launch and open the market by designing, building and implementing the central IT systems – known as CMOS – which sits at the heart of the market.

We also supported the development and evolution of the codes which govern the market.


What we do

Our aim, at all times, is to run an efficient, progressive and resilient market. To do this, it is vital that we use our skills and expertise to keep the market evolving and improving and that we work closely with our members and key stakeholders to build trust and confidence in making the market a success. As market operator, collaboration is key to this success.

We aspire to be collaborative in our approach to market improvement, to be transparent, and to champion innovative ways of reducing market friction, while ensuring a level playing field. This means reducing any barriers for companies entering the market and ensuring that all players have the same opportunities for operating and engaging with us and the industry.


Our role in the market is diverse and has continued to grow as the market has matured. As well as delivering our core services to members, our experts design and deploy the infrastructure, information and governance services that make it possible for customers to move smoothly from one supplier to another using our central IT system, which supports over 3,600 users, processing 90,000 transactions every day.

As the custodian of central market data, we also work closely with our members to drive improvements in the market through the Market Performance Framework (MPF), which is used to monitor and improve performance, provide assurance that trading parties are meeting their obligations and provide greater insight into the root causes of market frictions.

The market operates through a series of rules and arrangements known as Market Arrangement Codes (MAC). These are another key part of MOSL’s responsibilities. We provide expert guidance and secretariat services for the MAC Panel and its six committees, which oversee and review these rules, with valuable support and input from our members, may of whom are active members of the Panel, its committees and sub-groups.


Our values


We are a learning organisation, using our knowledge, experience and analytical skill to get inside complex issues. We make sound, evidence-based decisions in a fair and impartial way and look for new and innovative ways to solve problems.


We welcome diversity of opinion as a source of strength and are consultative in our approach. We understand the needs and views of others, recognising they may legitimately see things differently to us.                                                      


We are open, honest and accountable, communicating clearly and succinctly. We are clear about our intentions and the reasons behind our decisions. We cut through complexity to make things intuitive, clear and simple.


We use our knowledge to help shape both the market and the views of stakeholders in the best interest of the market. We take decisions, engage with issues and track progress.                                                                           

Our home

Since November 2018, we have been based in Southampton. You can find us at The White Building in the heart of the city.

Named as one of the most vibrant and fastest-growing economies in the UK, Southampton is attracting more businesses and start-ups than ever before. The ‘Master Plan’, launched by Southampton City Council in 2012, is projected to bring 24,000 jobs to the city by 2030 through a new business quarter and a £175 million redevelopment of the cultural quarter and waterfront area.

We are excited to be a part of this growing business environment and want to attract and invest in high-quality, highly-skilled people, allowing them to fulfil their potential and support in driving the market forward.

We are committed to investing in the future of our organisation and our people, for the benefit of the market and its customers.

To find out more about working for MOSL and to take a look at our current vacancies, visit our dedicated Careers Page.


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