On July 22nd, 1909, Castle Carrock put on its best frock, its newest bow tie and its shiniest shoes. The Mayor of Carlisle, was in town, along with 150 of the great and good from Carlisle – and from Castle Carrock. No doubt there were dozens of others who came along to witness the streamers, the big marquee and the music. All assembled in honour of the official opening of the brand new reservoir which built on the eastern edge of the village.

The ceremony of formally opening the Castle Carrock Reservoir was performed yesterday by the Mayor of Carlisle, Mr W B Maxwell. The event marked the completion of the greatest undertaking upon which the city of Carlisle has embarked.

Those who, at the invitation of the Mayor, witnessed the opening ceremony yesterday, must have felt pleased that the city’s water should have been drawn from so free, open and bracing a countryside; and, as they gazed on the immense reservoir which has converted the Castle Carrock valley into a lake, they could rest assured as to the adequacy as well as to the purity of the supply.

It had taken 12 years of argument and planning, almost a quarter of a million pounds, and the labour of five hundred men. But at last, the city of Carlisle and its surrounding area had a revolutionary, ready and reliable water supply fit for the start of the 20th century.

I live directly opposite the reservoir, and look out on it every day. I also regularly walk my dog around it. But I’m no engineer. And it wasn’t until I happened to stumble upon the date of the opening that I realised I had a centenary that needed marking. It was literally staring me in the face.

I stopped to think – where does the water come from to fill it up? Why was it built here? How was it built? Where does the water go to next? And how does the whole thing work?

This short booklet attempts to answer some of those questions.