When we think of medieval castles, we imagine them as impregnable fortresses, perched on rocky spurs and protected by mighty walls. But behind this apparent solidity was hidden a crucial question: the water resources management. How was the water supply guaranteed in structures often built far from rivers and aquifers? And how did the inhabitants of the castles survive during long periods of siege? From the rainwater collection from artesian wells to flooded moats, medieval castles were complex constructions in which water was both a vital resource and a defense tool.
The water collection system
One of the first aspects to consider when addressing this topic is the location of the castles. In most cases, in fact, they were built in elevated positionperched on mountain peaks or rocky spurs, so as to strengthen the defense and make it difficult for enemies to approach. If on the one hand this choice guaranteed a clear military advantage, on the other it entailed a significant criticality: the impossibility, or in any case the great difficulty, of digging wells to access the underground aquifers. The main solution, and also the most intuitive, was therefore the collection and the reuse of rainwater. Which meant, for the engineers of the time, transforming the entire surface of the castle into a precipitation collection system.
Roofs and walkways were then equipped with gutters, usually made of lead, which conveyed the rainwater towards a large collection tank, called impluvium. This was not a simple cistern dug into the ground, but part of a complex system which, in some cases, exploiting the natural slope, distributed the water in different areas of the castle through a pipeline network. The inside of the collection tanks were lined with cocciopestoa material of Roman origin that is particularly effective in guaranteeing the impermeability of surfaces, making the cisterns perfectly insulated and watertight, therefore suitable for storing water.
Artesian wells
In cases where the altitude of the site was not an insurmountable obstacle, deep excavations were made artesian wellswhich sometimes reached and exceeded 100 meters of depth, allowing direct access to underground water resources. During sieges, wells could represent both a point of strength and a vulnerability. On the one hand they were fundamental because they guaranteed thewater supply to the inhabitants who took refuge in the innermost part of the castle, allowing them to resist external attacks for a long time. On the other hand, this very centrality made them a strategic target for the besiegers who, in an attempt to force the besieged to surrender, tried to pollute the groundwater throwing animal carcasses or harmful substances into wells to make the water unusable.
During the siege phases, water therefore became a very precious resource. Its management took on almost one political dimension: the tanks were located in protected environments and access was strictly controlled; the keys were entrusted to very specific figures, often high court officials, closely linked to the lord of the castle. The latter, his family and the knights were reserved theclean, drinkable water. The remaining part, usually cloudy and contaminated, was instead destined for the lower classes, who sometimes tried to clean it by mixing it withvinegarused as a rudimentary disinfectant agent.
Water as a defense tool: the moat
In addition to being a vital resource, water in medieval castles was also used as a defense tool. Its first use in this area was aimed at creating the flooded ditch. Engineers dug a deep trench around the walls, which was then filled with water: an effective solution to prevent enemies from digging in underground tunnels under the city walls, compromising its stability and making it more vulnerable. The moat also played a key role in keeping siege engines, such as the assault towersmaking direct approaches to the castle difficult.
In the collective imagination, also fueled by cinema, the defenders overthrow boiling oil from the walls onto the attackers intent on scaling them. In reality, oil was a resource that was too expensive and difficult to manage, especially because it was extremely flammable; for this reason it was replaced with water, heated in large cauldrons and then thrown on the enemies, with devastating effects.
