Eversheds Sutherland has won a five-year contract to provide day-to-day legal work for Thames Water, taking over the managed legal services role held by Berwin Leighton Paisner (BLP).

Both firms have also been appointed to a new five-firm major projects panel alongside CMS Cameron McKenna Nabarro Olswang, Herbert Smith Freehills (HSF) and Pinsent Masons.

Eversheds' five-year managed legal services contract - secured after what Thames described as "a thorough and highly competitive tender process" – will start on 1 April next year, with the option to extend for a further three years.

The managed legal services role has been held by BLP since 2010, when an unconventional deal was struck which saw a Thames Water in-house legal team transfer from the company to become employees of the City law firm.

That 20-strong team will now be "insourced" to Eversheds Sutherland's offices after a three-month transition period.

The team will support Thames Water legal head Sarah Sear and the wider business on a range of day-to-day legal matters including competition, projects and planning, regulation, construction, real estate, commercial contracts, tax, disputes, energy, employment and health and safety.

Both BLP and Eversheds will now compete with fellow panel firms CMS, HSF and Pinsents for major projects work, which is distinct from the managed legal services arrangement.

Sear said: "Our managed legal services model has worked very well since we launched it in 2010 and, after a rigorous tender process, we are delighted to appoint Eversheds Sutherland as our new legal services provider for the next five years."

London public law firm Sharpe Pritchard advised Thames on the tender process.

Eversheds Sutherland CEO Lee Ranson added: "Securing work of this size and complexity has been one of the highlights of our year. We were able to demonstrate to Thames the difference in our innovative and creative approach to managing complex, high value legal services for our clients, such as our client relationships with IATA, Tyco and Turkish Airlines."

BLP's relationship with Thames Water, which is understood to have been worth around £5m a year to the firm, was renewed in 2014.

In a statement, the firm said: "BLP have been delighted to work with Thames over the past eight years as their main legal services provider under the ground-breaking managed legal service partnership. We look forward to continuing to support Thames as part of their specialist panel for major projects outside the scope of the managed legal service. BLP will not be making any further comments on what is a confidential client arrangement."

BLP's managed legal service division was launched when the Thames Water deal began in 2010. While the firm has come close to securing deals with Yorkshire Water and Colt Technology Services, the Thames Water deal is currently the division's only mandate.