Castlehill Reservoir and Edinburgh's Water Supply

17th-century water pipes

For many years Edinburgh lacked a safe, clean and reliable fresh water supply. Beginning with its early settlement on the castle rock, the people who lived here were reliant on rain water for drinking, washing, and for raising and cultivating crops. And whilst Scotland is known for its precipitation, Edinburgh gets less rain than the rest of the country, on average!

Even into the medieval period this left the great fortification of Edinburgh Castle at a significant disadvantage - whilst it was militarily safe from attack, its great weakness was its limited space for raising food, and its limited supplies of fresh water.

Of the many times that Edinburgh Castle changed hands between the Scots and the English, it was most common for the handover to happen as a result of the castle surrendering due to its lack of resources. The relatively small well, just a few metres deep, and serving as a cistern for storing water rather than accessing an underground aquifer, is still visible at the top of Edinburgh Castle today.

---

The former reservoir on Castlehill

In the fifteenth century, the valley to the north of the castle rock was dammed, and the stream which ran into it created an artificial lake called the Nor Loch. This valley is today Edinburgh's Princes Street Gardens. This artificial lake served a number of purposes, both defensive and practical - not only was the lake effectively a large castle moat, preventing access to the city from the north, it also provided the city with a regular supply of water.

​This was not a particularly effective solution to the city's water issue, however. The valleys on either side of the Royal Mile were also sewerage outlets, where all the waste drained off the streets. Long before the consequences of drinking contaminated and dirty water were understood, the citizens of Edinburgh would have been drinking water which would have been heavy with human and animal waste that had washed down from the city. As the population of the city rose, this supply of water became increasingly insufficient.

---

Original wellhead in the Grassmarket

In 1624, the city was granted an act of parliament which allowed them to bring fresh water into Edinburgh for the first time. Springs in the Pentland Hills to the south of Edinburgh were connected to the city via a network of wooden pipes - basically hollowed out tree trunks - across the landscape and up to the top of the Royal Mile, where a reservoir had been built to store the water.​

​The reservoir is still there on Castlehill - today it's the city's only surviving tartan weaving mill - five storeys deep into the ground. 

​In 1674, after fifty years of engineering work to connect the supply, fresh water flowed to Edinburgh's residents for the first time, from the reservoir on the Castlehill to twelve wells around the Old Town. Some of those wells still survive, with two of them in their original locations, on the Grassmarket and outside John Knox's House. 

​This revolutionary system improved Edinburgh's health and hygiene immeasurably into the eighteenth century, paving the way for the city to become the seat of learning and innovation during the period known as the Scottish Enlightenment. ​

---

Torduff Reservoir in the Pentland Hills

Today there are several Victorian-era reservoirs in the hills to the south of Edinburgh, from where fresh water was piped into the city during the nineteenth century.

​These reservoirs today are a peaceful retreat from the hustle and bustle of the city, and offer visitors the chance to take advantage of Edinburgh's proximity to the countryside. They no longer supply water to the city, but remain as evidence of the remarkable and industrial efforts made to transform Edinburgh's public health and wellbeing in the recent past.

​Explore more of Edinburgh's innovative history with my private walking tours!

---