Northumbrian Water has projects and contracts supplying water and sewage needs worldwide, not least its service to 2.6m people in the North-East.

Business Editor Mike Parker travelled to Gibraltar to see the firm's involvement in a colony which has historically struggled to supply water to its people.

THE hard, imposing Rock of Gibraltar holds the key to the water worries of a British colony which boasts a mere 30,000 residents and six million visitors each year.

Thirty-two miles of caves gouged through the 7,500sq km mass have turned the Rock into Swiss cheese. It is a legacy from times of conflict when ammunition, supplies and troops needed safe havens.

Now the tunnels house an ally of a different, but equally important, kind - some of the purest water on the planet.

It is so pure after treatment that chemists put beneficial elements back into it to give it the properties of regular drinking water.

Somewhat surprisingly, Gibraltar has a similar annual rainfall to the North-East, but the bulk is over five months, making it difficult to harvest the natural resource.

Instead it relies on de-salination processes and reverse osmosis treatment - where varying pressure levels are used to pull fresh water through semi-permeable membranes - to provide drinking water.

The colony has a dual water system, where the toilet flush is saline and the tap water is drinkable.

Northumbrian Water first became involved in Gibraltar when, still Government- owned, it shipped water extracted from Kielder Water by tankers to help the peninsula.

Now, in the form of its subsidiary Lyonnaise Des Eaux (Gibraltar), it employs many former Government water department workers and has a two-thirds stake. The other third is retained in state control.

Manuel Perez, managing director in Gibraltar, said: "We have had links with the North-East for a long time. It was mainly arising from the fact you had water to spare and we needed water desperately.

"The relationship is still excellent. I do not know what it is about the people from the North-East and here, but we tend to hit it off."

That relationship extends to the highest echelons of the Government of Gibraltar.

Peter Caruana, chief minister, said: "The Government of Gibraltar very much values its partnership with Northumbrian Water.

"It is difficult for small places like Gibraltar to keep abreast of the latest technology and latest techniques.

"A partner that is at the forefront of this industry in a larger country provides us with an ideal opportunity for technology and know-how transfer that otherwise a small community like this would always lag a long way behind."

The exchange of information has been extensive with delegations from Lyonnaise Des Eaux (Gibraltar) utilising Northumbrian Water's research facility on Tyneside.

In return, other arms of the group use the harsh, saline conditions in Gibraltar to test new equipment.

The knowledge learned in Gibraltar will be used to tackle other areas undergoing enormous climatic change - not least in Essex and Suffolk Water area, owned by NW, which is the driest in Britain.

Alistair Baker, communications manager at Northumbrian Water, said: "As a group, we are seeing water patterns change and climatic changes in different areas. If you work together in a big group and pool that knowledge, then together we can make a substantial difference and make efficiencies, best practice and best solutions to the problem."

The contract is 11 years into a 30-year lifespan, which could be extended at the end of Northumbrian Water's tenure, if both parties agree.

Mr Baker said: "Everywhere has its own challenges. Gibraltar has more than most when it comes to supplying water.

"But, with the support of the Government of Gibraltar, we hope to continue our work for the next 20 years and more."