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About us

Roles and responsibilities

The Water Act 2014 established the framework to create a market that will allow 1.2 million businesses and other non-household customers of providers based mainly or wholly in England to choose their supplier of water and waste water retail services.

The Open Water programme was set up by the UK Government to deliver the competitive market by April 2017.

The key organisations responsible for delivering the new market are Defra, Ofwat and MOSL.

The programme was overseen by Open Water Markets Limited (OWML) until August 2015, when its activities were transitioned into MOSL and Ofwat.

As a key partner, MOSL has a central role in developing and delivering the core systems and processes that will enable customers to switch between suppliers. MOSL is actively engaging with participants and coordinating activity across the industry to support the programme in the run up to market opening in April 2017. 

Open Water encourages stakeholders' active participation. We publish relevant papers, consultation documents and notice of stakeholders' meetings and workshops on this website.

Decision making

The Open Water programme is led by a Management Group of senior executives from MOSL, Defra and Ofwat. This group (the RMOMG) is responsible for:

  • overall programme governance and leadership;
  • oversight of plans, budgets, risks and policy issues.

Chaired by Defra, the group takes programme-level decisions and delegates day-to-day decision making to the Programme Management Office and the individual work streams. It is supported by a number of groups that report to it covering programme management, policy issues and communications.

Find out more about the overall governance of Open Water.

Partners' roles and responsibilities

The table below gives an overview of the key responsibilities specific to each Open Water partner.


Find out more about roles and responsibilities for the programme.

Our plans


An integrated work plan for the Open Water programme is published each month on Ofwat's website.


The vision


The Open Water programme was created to support the delivery of a retail water market for non-household customers in April 2017. The opening of the market is the cornerstone of the UK Government’s vision for the future of water management in England, as set out in the Water White Paper, 'Water for Life'.

It aims to develop:

  • A resilient water sector, in which water companies are more efficient and customer focused, and in which water is appropriately valued.
  • An improved range and quality of services offered to customers by removing barriers to competition, fostering innovation and efficiency, and encouraging new businesses to enter the market.
  • Markets where all participants operate on a level playing field.
  • A more sustainable use of resources and keener pricing for customers.

Success criteria

The following high-level success criteria for the market were agreed in 2012 and revised slightly in January 2016:

  • All non-household customers have a choice and are aware of how they can exercise that choice. They are in a position to negotiate better targeted, more efficient and more cost-effective services.
  • Outcomes are cost-beneficial for the majority of customers.
  • The new competitive markets are fair, transparent and efficient.
  • The market delivers a seamless customer experience in England and Scotland.
  • The market incentivises innovation in services by both existing and new market participants.
  • The market encourages diversity of entry and minimises barriers to entry.

MOSL has developed a set of principles, based on the success criteria outlined above and reflecting its specific delivery role. Find out more about MOSL.


OWML board papers

You can find links to the papers of all OWML board meetings, which took place between February 2014 and July 2015 here.

OWML’s activities were transitioned into Ofwat and MOSL with effect from 1 August 2015.


Glossary of Terms




An allowance or ‘credit’, which reduces a customers water bill based on specific conditions or events e.g. water used for fire fighting purposes cannot be charged for therefore customers are refunded any water charged if it has been used for this purpose, and leakage allowances, where customers receive a rebate for water lost through leakage on their own pipe work.

Central Registration System

The database in which the data for all contestable premises and service points are held.

Charges Scheme

Tariffs setting out retail and wholesale charges that incumbent water companies charge their customers.

Charging Guidance

The mechanism by which the Government will inform the content of Ofwat’s charging rules (see below). The Government will publish overarching statutory guidance in April 2015 that will set out its approach to regulating charges. The Government may also issue more detailed guidance that relates to individual areas such as the water supply and sewerage licensing (WSSL) regime, which will sit below the high level guidance. Ofwat must have regard to the charging guidance when they set charging rules.

Charging Principles

A statement of high level principles published by Defra alongside the Water Bill that will underpin the development of the future charging guidance and give a broad indication of Government policy on charging issues.

Charging Rules

The mechanism by which Ofwat controls the charges that undertakers may impose on various parties. Ofwat must issue charging rules to cover undertakers’ charges to their direct customers for water or sewerage services (through charges schemes) as well as charges to licensees for “use” of the water or sewerage networks. Ofwat may issue further rules to cover charges to developers and customers for connecting premises to the network. These rules can be issued separately or as part of the same document. Ofwat may also issue rules on charges in other areas, such as bulk supply agreements, main connection agreements, the self-lay regime and the sale of water to undertakers by persons other than water companies.

Code Panel

The group responsible for governance of code modification.


The mechanism by which Ofwat will regulate the various agreements that undertakers make with other parties. The contents will vary from code to code but, generally, they may contain standard terms and conditions, principles for agreeing terms, or principles for how negotiations shall be run. For example, codes on licensing will concern the terms of the agreements between undertakers and licensees for the use of the water supply or sewerage system. In addition to licensing, Ofwat may also issue codes to cover bulk supply and main connection agreements, infrastructure adoption agreements (self-lay regime) and the sale of water to undertakers by persons other than water companies. The term encompasses codes that are commonly known as market codes, operational codes and access codes.

Common Wholesale Contract

A defined contract between the Retailer and the Wholesaler on standardised terms and conditions which sets out the services the Wholesaler will provide to the Retailer and the commercial terms on which they will be provided.

Contracting Authority

The legal entity to which the Service Provider is contracted [This may initially be Ofwat but may novate across to the Market Operator].

Current Retailer

The retailer which the customer currently contracts their water and sewerage services. During the switching process this is the retailer the customer wishes to switch from.


End consumer of the water and sewerage service.


The breaking down of averaged tariffs to their smaller geographic constituents.

Deemed Contract

Where a service is provided to a customer without a formal contract being signed [This happens by default until another offer is agreed and will be in place with the majority of incumbent contestable customers at market opening, and for customers when they move into new premises].

Default Contract

A defined contract, available to all customers, between the retailer and the customer on Default Tariff Price, Default Service Levels and terms & conditions [with no discount included and currently only applicable to incumbent retailers].

Default Service Levels

The minimum level of service available to all Customers on a Default [or Deemed] Contract [currently only applicable to incumbent retailers].

Default Tariff Price

A maximum tariff that will be offered to Customers made up of an allowed Retail Charge that has been added to the Wholesale Charge [currently only applicable to incumbent retailers].

Financial Settlement Process

The settlement of the Wholesale Charges between the Wholesaler and Retailer, including any reconciliation process.

Gap Premises

Premises which are identified as missing on the central registration system and or not allocated to a Retailer and/or Wholesaler.


Industry Data Exchange. The systems, data interfaces and data flows which allow passing of relevant data between Market Participants to enable market processes to be executed.

Imbalance Settlement

The settlement of differences between contracted supply volumes and actual volumes bilaterally agreed between the Upstream Provider and the Retailer (which may involve buying or selling water to/from the wholesaler at different rates).

Incidence Effects

The direct or indirect consequences of making any change to the status quo, particularly important regarding structural changes in tariffs that impact different customers in different ways and cause significant changes to their charges.

Incumbent Water Company

The water and/or sewerage undertaker that holds the de facto monopoly to provide services to premises in its area of appointment. It is also responsible for maintaining and operating the public water supply and/or sewerage systems. Although “insets” are also undertakers, the term “incumbent” does not include inset appointees for the purpose of describing the competitive market for providing services to new developments. However, inset appointees may be considered as incumbents in the context of the water supply and sewerage licensing regime because non-household customers will be eligible to switch suppliers in the reformed retail market.

Incumbent retailer

Retailer of one of the vertically integrated water and/or sewerage companies who can only operate within their geographic area.

Inset appointee/Inset

A company that replaces the undertaker for a specific geographic area within the area of an existing undertaker. This usually happens where the customers are “unserved” (such as on a new development) or qualify as large users (i.e. they expect to use more than 50Ml in England or 250Ml in Wales – for example a paper mill). The inset regime is sometimes known as new appointments and variations (NAVs). However, the term “NAV” also refers to a variation of the appointment area of an incumbent water company, for example when incumbent water companies agree to change the boundaries between them.


The holder of a water supply licence or sewerage licence.

Market Monitoring

Processes to ensure compliance with Codes by Market Participants undertaken by the Market Operator.

Market Operator

A private sector organisation, limited by guarantee and owned by all market participants, that provides services that help enable and facilitate the effective operation of the competitive market arrangements.

Market Operator Assurance

Audit of the Market Operator functions and governance.

Market Participants

All parties involved in the Retail (and later Upstream) Market, including but not limited to Retailers, Wholesalers and the Market Operator, but explicitly excluding Customers.

Minimum Wholesale Service Levels

The minimum level of service provided by the Wholesaler and available to all Retailers.

New Appointee (NAV)

A company that has replaced another to become the appointed Undertaker for a specific geographical area under the New Appointment and Variation regime (sometime referred to as an inset appointment).

New Entrant

A new business entering the water market, i.e. a licensee or inset appointee or an applicant to be a licensee/inset appointee. The term may also include self-lay operators in a wider context (see below).

New Retailer

The Retailer the Customer wishes to switch to.

Non-Potable Water

Water that has not been treated to the standard required for it to enter the public distribution network. It is often used in industrial processes.

Operational Services

Operational Services refers to services provided by wholesalers to retailers, or retailer to wholesalers, which are in addition to the continuously provided water and sewerage services and meter rental. Often this work is requested by the retailer on behalf of the customer or is required by the wholesaler to ensure the wholesale service is delivered.

Performance Monitoring

Monitoring of central systems and Service Provider performance by the Market Operator.


Land and buildings together considered as a property.


Customer-facing services, for example billing, meter reading and call centre services. The full list of retail services for the purposes of the competitive market is outlined in the Ofwat price review methodology.

Retail Authorisation

This will enable a licensee to provide retail services to all non-household customers in an English undertaker’s area, including to its own premises (self-supply).

Retail Developer Services

Services carried out by Retailers [and licensees post 2017] providing developers with information and carrying out the administration for new connections.

Retail Licensee

New entrant with a retail licence, including incumbent licensed retailers able to operate outside their geographical area.

Retail Market

Post 2017 market allowing non-domestic customers choice over which Retailer delivers there water/sewerage services. This encompasses the systems, processes and governance required to deliver such a market.

Retail Tariff

The tariff offered by Retailers to Customers.


Provider of the retail service to the end customer, dealing with all customer services as outlined within the Ofwat pricing methodology statement such as billing, payment handling, customer calls, meter reading and administering new connections. Could be an Incumbent Retailer or a Retail Licensee.

Retailer of Last Resort

A licensee or incumbent who is assigned the customer(s) of a retailer that has left the market, where those customers have not chosen an alternative retailer themselves.

Self-Lay Regime

This permits a developer to install (or use a contractor to install) the pipework for a new water main or sewer which will be subsequently adopted by the relevant undertaker. Adoption of the pipework is subject to the developer meeting conditions, including build requirements, previously agreed between the developer and undertaker.

Self Supply Licensee

A customer with a water supply or sewerage licence that provides retail services to its own premises and those of its associates (for example, subsidiaries or partners). This will only be available for customers in the area of English undertakers.

Service Point

The points of supply of service to the Customer. This may be for water supply, sewerage services, trade effluent and any other service within the wholesale service catalogue.

Service Provider

The company or companies contracted by the Contracting Authority to design, build and operate the market processes.


The calculation of charges and processing of payments between market participants to remunerate them for the goods and/or services they have provided.

Sewerage Licence

A sewerage licence, introduced by the Water Bill, will allow entry into the market for wastewater and sludge services for the purpose of providing retail and/or upstream services. A licensee may hold one or more of three “authorisations” within a sewerage licence.

Sewerage wholesaler

Incumbent company supplying sewerage services.

Standard Retail Contract

An industry standard contract, available to all Customers, agreed between the Retailer and the Customer on standardised terms and conditions, with any agreed discount included [the introduction of a standard contract has been suggested by retail customers but has yet to be agreed as necessary].

Trade Effluent

Untreated, non-domestic sewage from commercial premises.


A company who has statutory powers and duties to supply water and/or sewerage services to premises within an appointed geographical area under the Water Industry Act 1991. These are the incumbent water companies and inset appointees. The undertaker has complete control of the water supply and/or sewerage system in its appointment area. Licensees must therefore “use” their networks in order to serve or supply customers.

Unserved Premises

Premises on the central registration system that do not have a Service Point associated with them [e.g. because the property has private/no services available].


The elements of the water and sewerage value chain that do not directly involve the customer, i.e. those activities related to the abstraction or collection of water and sewerage, treatment and distribution. Upstream services are services that are not covered by the retail definition in Ofwat’s price review methodology. The Bill is only extending competition for the wholesale element of upstream activities. There will be no competition regime for distribution services.

Upstream Market

Post 2017+ market allowing new entrants to undertake upstream activities, such as providing water resources into the water network or removal of products from the sewerage network.

Upstream Provider

New entrant within the Upstream Market, providing resources into the water supply network and/or removal of products from the sewerage network.

Vacant Property

Premises that are confirmed vacant and which may be temporarily exempt from business rates.

Void Property

Premises with no known occupier (either the property is vacant or the customer has failed to notify the Retailer of a move in).

Water supply wholesaler

Incumbent company providing physical water services.


The inputting of water to or the removal of sewage from the network either by an incumbent water company, a neighbouring incumbent or by a licensee with a wholesale or disposal authorisation. In the context of the Bill, wholesale services provided by a licensee do not include distribution services (i.e. the ownership and operation of pipes) but do include the ownership of mains and pipes by inset appointees.

Wholesale Authorisation

This will enable a licensee to provide water and/or sewerage wholesale services to all non-household customers with the same or a different retail licensee in an English undertaker’s area. The Water Bill will remove the combined supply licence so that licensees can specialise in the services they want to provide to customers, i.e. a person that wants to input water will not have to provide retail services as well.

Wholesale Charges Scheme

The publication of Wholesale Tariffs by incumbents required under s143 of WIA91

Wholesale Services Catalogue

The list of chargeable wholesale services available in the market.

Wholesale Tariff

The tariff offered by Wholesalers to Retailers.

Wholesale Tariff Structure

The structure and thresholds of wholesale tariffs offered by a wholesaler to retailers and which are often created based on customer type, for example different tariffs exist for customers who use low or high volumes of water. The wholesale tariff structures are different for each wholesaler in England.


The water company who provides the service to the Service Point and undertakes the wholesale activities as set out in Ofwat’s pricing methodology. This includes the supply of water and waste water services, meter ownership, installation, maintenance and replacement, trade effluent compliance and monitoring, disconnections and reconnections.

WIA - Water Industry Act 1991

This is the main piece of primary legislation that concerns the regulation of the water industry, including water and sewerage services.

WSL (Water Supply Licence)

A water supply licence will allow entry into the competitive water supply market for the purpose of providing retail and/or upstream services. A licensee may hold one or more of four “authorisations” within a water supply licence.