One place that I really loved on my Welsh weekend was the Elan Valley, both from an engineering point of view and a great place to ride a bike. Thought I'd put a thread together- so journey with me if you will, back to Birmingham in Victorian times...

The industrial revolution is in full swing. People are leaving behind the rural life, and flocking to the cities in search of work.

In Birmingham, the 'city of a thousand trades', this causes problems with sanitation. Outbreaks of dysentery, typhoid and cholera are commonplace.

Various ideas were mooted to supply the second city with enough water for both the growing population and the needs of industry. Civil engineer James Mansergh settled on the Elan and Claerwan valleys in mid-Wales.

There were four main reasons that this scheme was favoured-

1. Lots of rain.
2. Narrow valleys, making dam-building easier.
3. A bedrock impermeable to water.
4. Gravity.

The Elan Valley is 52m above the city of Birmingham. This meant that no pumping stations would need to be built. Instead the water could travel the 73 miles down a pipeline with a gradient of 1:2350. It would take three days for the water to make the journey.

The leader of Birmingham City Council was Joseph Chamberlain. He petitioned Parliament to pass the Birmingham Corporation Water Act in 1892, which allowed the council to effect compulsory purchase of the land needed for the project- approximately 69 square miles.

I can't imagine this went down well in Wales. 'Wait, you want to flood our valley so the Brummies can do the washing up?'

More than a 100 people were displaced, 18 farms, a school and a church were demolished.

Work began in 1893, firstly on a 28-mile railway capable of moving 1000 tons of materials a day, and then on the first four dams. 5000 people worked on the project, most living in specially-built accommodation in Elan village. The camp was quite progressive for the time.

Facilities included a hospital, a bath house, a pub (men only), a library, a public hall, shop and canteen. There was also a school for under-11s. At 11, children were expected to start work.

After ten years of construction, the project to supply water to Birmingham was opened by King Edward VII on July 21st 1904.

Phase two was due to start in the 1930s, but was delayed due to the Second World War. The plan had been to build three more dams and flood the Claerwan valley, but advances in concrete technology meant only one dam had to be built- Claerwan dam.

Construction started in 1946. A 470-strong workforce was involved in the project, including 100 Italian stonemasons. Bloody foreigners, coming over here and providing our cities with drinking water! The dam was opened by Queen Elizabeth II in 1952.

Another interesting piece of history- in 1942, the Nant-y-Gro dam, built to provide water for the workers' village, was used by Barnes Wallis to prove his theory that an underwater explosion could collapse a dam wall, leading to the famous Dambusters and the bouncing bomb.

So that's the history- how about the cycling? It was a memorable day on the bike. I got there at 7am, intending to only spend part of the morning there. I was still there at 5pm, derailing my schedule and necessitating a call to my boss to book an extra day off work!

Map of the dams and reservoirs.

Start of the ride.

Caban-coch dam, opened 1904.

Caban-coch reservoir. The path is part of the old railway line.

Garreg-Dhu dam, opened 1904.

Garreg-Dhu reservoir.

Pen-y-Garreg dam, opened 1904.

Pen-y-Garreg reservoir.

Craig Goch dam, opened in 1904.

The dam in action!

Craig Goch reservoir.

The ride to Claerwan dam.

Claerwan dam, opened in 1952.

View from the dam.

Claerwan reservoir.

So all in all, Sunday was an incredible day. And the funny thing is, I hadn't heard of the Elan Valley on the Saturday! To me, this is where Twitter comes into its own. Half a dozen people recommended it to me, so I went- and had one of the best days ever on a bike