How did Roman Aqueducts work?

let's explore the aqueducts of Rome how do they work what was their function in the Roman city these are incredible symbols of Roman engineering they are some of the most iconic features of the Roman Empire and of course there's so much that goes into this construction the serving the planning and the execution for the benefit of the citizens of Rome let's explore the aqueducts of the Roman Empire before the aqueducts where did Romans get their water from well they collected rain water into cisterns they drew water from some of the local Springs available to them and they drew water from the Tiber but it all started to change in 312 BC with the construction of the first aqueduct the aqua apia coincidentally coming into being alongside the first major paved Road of ancient Rome the Via apia and from there things really took off how exactly does it work an aqueduct works by gravity flow you must find a water source at a higher elevation than your city then you direct the water from Springs or river or lake into a man-made Channel basically you're making a new conduit a man-made River into the City and sometimes they're obstacles you have to drill through Hills or mountains or sometimes there's a valley and you have to prop up that Channel with a bridge this is essentially what an aqueduct is and therefore the majority of the construction was Underground so for all those incredible miles of arches of various aqueducts throughout the Roman Empire including Rome itself those beautiful arcades represent a fraction of the overall length of a given Aqueduct line so with the progression of time and the construction of 11 aqueducts the Romans would go further in further afield to find better sources of water at a higher elevation thereby ensuring the water would eventually get to all the Seven Hills of Rome we have fantastic resources from Antiquity we have Vitruvius in his 10 books of architecture he writes about aqueducts in book eight we have frontinus active in the reign of nerva who was the kurato aquarium he was in charge of the aqueducts and he wrote about each Aqueduct the amount of water they brought into the city of Rome and how they were maintained so we have fantastic sources from Antiquity as our guide so you start off with identifying a source which could be a spring a river or a lake but pretty much the Romans preferred the Springs because the water quality was so much better and from that original Source at a higher elevation from the city you had to establish the gradient you had to bring that water through gravity flow into the city while how steep was that slope Vitruvius says it had to be 1 in 200 or half of a percent but there is some discussion that the Latin is corrupt in the passage in Vitruvius Now Plenty the Elder says it should be 0. 02 percent that's one meter drop out of 4 800 meters but really when we start to look at aqueducts throughout the Empire we see that it's usually between a 0. 2 and a .

03 percent slope and that means a one meter drop in 3350 meters that's an incredible amount of precision how do the Romans do it they had a number of tools now we know one was the groma this was an instrument used as a basic tool for horizontal alignment and the chroma was used to establish a straight line or right angle it's a surveying tool for constructing roads as well as aqueducts Vitruvius discusses three tools the diopra essentially an ancient theatolite is a quite complex instrument detailed by hero of Alexandria it was used both for horizontal and vertical measurement and was used to measure distance another tool was the quartobates a water level acting like a modern Bubble Level it consisted of a six meter long beam of wooden legs with a series of plumb bobs for establishing the angle of the slope he also mentions another water level known as the Libra the majority of this this spacos the channel through its the water flowed was constructed in the natural landscape here we're seeing portions of the aqua Claudia channel so most of it was just literally carving through Limestone in this case and sealing it over with waterproof cement to make sure that the water didn't seep out here's an example of the aqua marcha we're actually in the speakers were looking at the base look at the sidewalls we have the exposed open signinum the waterproof cement with crushed peaches of ceramics that would ensure the water would not seep out as it flowed through but it was hard water so calcium eventually gets deposited on the walls of the spaces we can see that deposit still today right here as the man-made water Channel approached the city it had to be propped up on a series of arcades to maintain that gravity flow and of course by the time those channels arrived in the city of Rome they came at a great height in the Imperial period and one important place we can observe that Majesty of the aqueduct channels is at Porta majority on the Escalon Hill in fact eight of the 11 aqueducts of ancient Rome entered Rome at this high point so that you can maintain the great height of the aqueducts coming into the city now here we can see in the claudian gate that celebrates the arrival of aqueducts to spakest channels the lower one from the aqua Claudia and the upper one from the honest Novus nearby you have the remains of the space channels of three earlier aqueducts at the bottom the aqua marcha of the second century BC piggybacking on top from a distinct Source the aqua tepola and on top of that date the time of Agrippa the aqua Julia as the water flowed closer to the city of Rome propped up on the arcades there were a number of opportunities to purify the quality of the water and in fact you have the construction of a series of castella now here's one from Segovia the famous aqueduct in Spain and it's an opportunity then for the impurities to drop out into this Basin on the way that the water flowed into the rest of the city also coming into the city you have a culmination point of the castellum aqua now this was a Structure where you actually then began to funnel out the water into distinct channels someone go to the baths so I'm gonna go to the public fountains some would go to the homes of private individuals that would pay for it and a great example we see here in the castellum aqua of Pompeii but even more important more famous is this one in the city of neem attached to the ponti guard Aqueduct and we can see how complex the distribution was of the water into various channels and when we think about the piping what was it made out of it can be made of stone terracotta but the Romans principally use lead because lead was abundant and cheap obtained through the refining process of silver production so he had all this lead it at a low melting point and you were able then to produce this amazing piping all throughout your city modern estimates of flow rates are very difficult to assess now it's been determined that it's around 1 to 1. 5 meters per second that's an average speed of three and a half to five and a half kilometers an hour that would have ultimately brought to Rome between 320 000 cubic meters of water a day some estimates put it as high as 1 million cubic meters of water a day now against these modern estimates though we have the ancient sources frontinus's unit of measurement is the queenaria and it's the smallest lead pipe made and the term comes from Five Fingers five digits that form then the diameter of a given pipe so frontinus is measuring the flow rate by the pipe diameter this measurement has caused quite a bit of difficulty to reconcile modern assessments with the ancient calculations the reality is that the water coming mostly from Springs would have been frequently constantly depositing calcium and other minerals that would have served to finally restrict the flow of water in a given spaces now there are slaves to maintain the water channels to maintain the arcades and clean out this accumulated material called Center but the reality is when we look inside a number of spacious channels we see quite a heavy amount of deposit of calcium in fact one of the most striking examples we have of calcium deposit is here in the spaces at the top of the Ponte guard Aqueduct the amount deposited is impressive so we can imagine that even with the estimates of water flows and Antiquity or even modern estimates today a huge impact would have been on the Restriction of that water flow over the centuries what would the awkward well they're built from the 4th Century BC into the third Century A. D parallel to Rome's increased population up to a million people were sustained in part because of the Abundant supply of water from so many aqueducts but it was also geared for public enjoyment especially the baths so the aqueducts were a great public amenity and Antiquity in Roman cities throughout the empire now plenty of the Elder tells us that Agrippa formed 700 wells in addition to 500 fountains and 130 reservoirs many adorned with statues of Marvel and bronze and 400 marble columns all this for the aqueducts that he constructed in the reign of Augustus moving into the 4th Century A.

D we have a catalog that details there were 19 Aqueduct lines feeding 1352 public fountains 15 nympheta big public fountains 11 Imperial thermi bath complexes like the baths of karakalla and 856 public baths and 254 reservoirs now when the water came into the city a portion of it was already diverted outside the city limits for private use mostly private Villas says frontinus within the city frontina specified three clearly distinct groups for water consumption first primarily was for public baths and for other lines for the special privilege use of the Roman Emperor himself the second group consisted of public use for the military official establishments theaters public fountains and private bats the third section was for private users bringing lines directly into one's home and also for Industries such as the Fullers the fallonica water from the aqueducts was also used to flush out the public latrines frequently located in public baths and near the Forum by the 4th Century they were documented as being 144 public toilets in the city of Rome when we looked throughout the Empire we'll find Spectacular examples of all these activities that underline the importance and the prestige associated with having an aqueduct in your city from the Monumental underground Basilica of Constantinople to the sprawling Aqueduct on the beach by caesarea maritima in Israel Israel to the Punta guard in southern France to this sprawling aqueductive Hadrian of Carthage to The Elegant arcades of the Aqueduct of Segovia in Spain the narrow arcades of Los Milagros Aqueduct which is for Merida in Spain fed from a reservoir called proserpina Dam that still exists today back in Rome we enjoy the channels of the ancient aqueducts as impressive ruins in the park of the aqueducts as well as some of the lines that were put back in use in the papal period the most famous of which is the aqua Virgo still flowing from its natural springs all the way into the heart of Rome the campus marshes flowing to other fountains in the center including those in Piazza navona thanks for tuning in and be sure to subscribe to our YouTube channel and get our newsletter at interromelive.