Something I was reading about the history of Venice this weekend made me wonder – where does Venice get its water?
Venice has a history going back to Roman times. It’s built on a set of small islands in a salt marsh, and it’s conjectured that the city got its start as a protected retreat from the encroaching Germanic invaders. Okay – retreting to an easily-defended island in a marsh ids good. But if you’re going to hold out somewhere, you need a water supply. Vencice not only had a water supply, it had enough of one to become, for several centuries, a world power. But it’s a relatively small, mostly built-up island. Where does its water come from? It needs a pretty good supply og potable fresh water to support all those people. Thety couldn’t be transporting it over from the mainland, or else it would never have got its start.
I know that some islands surrounded by salt water can support a small group of people with rainwater that comes down from the high point. Even tiny Aruba, with its piddling little Haystack Mountain could support a small populatioon with the runoff from there. But Aruba couldn’t support a large population until the past hundred years or so, when they put in industrial desalination plants. Venice didn’t have industrial desalination plants, but they had a population big enouggh to trade goods, fight wars, and build St. Mark’s Square. So where did the drinking water for Venice come from?
From wells, at least in the past. All of those paved courtyards were designed to drain through sand into cisterns. Allegedly filtered by the sand, the water was potable. I’ve got some photos of one of them somewhere.
This page (a review of a book on Venetian architecture) claims in the second-to-last paragraph that Venice had no natural water supply, relying on rain water collected in cisterns instead.
I don’t see why this should not be feasible. The fact that Venice was a major trading and military power does not necessarily mean that it had to have a large population - quite on the contrary, being a center of commerce has more to do with being located at the intersection of important trade routes, not with having a large manpower in the city. According to Wiki, the historic city itself has a population of 62,000 itself; I assume this was significantly less in previous centuries, although there has been a trend in the past few decades of Venetians moving out of the city proper.
And you should also keep in mind that the water consumption per capita was lower than today - no thirsty industries or tourists to maintain. The region of Venice is not particularly poor in rainfall, so I assume a population of a few ten thousand people in the middle ages and early modern era could in fact have been sustained largely on collected rain water.
I speculate that in the past, when pigeons were considered less a picturesque addition to tourist photographs and more a source of protein, pigeons on the hoof, as it were, were less common than now.
Maybe, but we’re not talking about a subsistence economy here – Venice was building and producing things. Heck, they were building Vencice itself. Even if you use water from the canals where you can, there are some things you’re going to want clean non-salt water for. And for a world power, with all the people required for the muscle power and the bureaucracy, I think you’d want a pretty big water supply.
I can buy people using cisterns to store runoff from roofs and plazas – but I’ve seen the photos of the plazas being overwhelmed by the local (salty) canal water. Venice subsisting entirely on collected rainwater makes it seem pretty much of an edgy existence, with one good catastrophe wiping the city out.
Currently, all the wells have been covered, and Venice gets it’s water from the mainland. It was determined that using wellwater was a large contributor to the sinking of Venice.
The historic centre of Venice was actually much more populous a few centuries ago. According to the Venetian history book I happen to have here, the population in 1581 was no less than 134,861 people, which is more than twice the current population. The population of Venice reached a high of 174,969 in 1951.
First of all, hi and sorry for the devastation that english will probably pass upon my non-native speaker’s hands.
Couldn’t resist trying to answer a question about my city. Well, the historical centre of my city, but you get the idea…
Yes: it was mostly the wells (pozzi). At least before the first acquaducts (that came to be a little before 1900), they did quite a job to provide water to a city that was in water and didn’t have any water.
This idea (have a structure that by itself collects rainwater, retains it and filters it, making it pass sand to filter it, to have it pure just under the "real"well, the tunnel) seems to have come from natural structures that worked more or less like that: the litorals of the lagoon (lidi) are made of sand, at least in the part facing the open sea, and sometimes work like that. It was just a matter of time trying to emulate this in all the lagoon.
What I don’t find is some numbers, like how much water did they store/how many wells they had in all the city at its apex; 'cause what you see now, the closed vere da pozzo in the campi, are probably less than half of the real structures people used. Apart that bigger wells, in all the palaces they had wells, but so did in popular houses, sometimes in communal places, sometimes even in the kitchen, and now that’s of course more difficult to see (or even to know if it’s your house).
I could find only this page that comes near to showing a decent image of a well, and some nice vere.
I would say that thinking now about a city that in they day would house 200,000 inhabitants, furnished mostly by wells, seems kind hard. But:
The wells were very strictly regulated, being perhaps the most strategic asset in the city after the fleet. There were not one, but three magistratures for them, and they could only be built by a specific gild. Every public well had someone with its keys, to open it two times a day.
Yes, building a well was quite an engineering feat, mostly because even if it weren’t so terribly large (a 5 meters in depth at most, I think), they had to collect just rainwater. Salt was anathema for these wells; many were built in a way that the manholes were a little taller than the rest of the soil, just in case. Clay was used for isolating the thing beyond the soil.
But they had quite a time to build them all up, and most of all, if your well was under construction, there was another one just right there to use.
And, acqua alta (tides flooding the city) is mostly a thing of the last two centuries.
Sands DO filter water well. Maybe now it wouldn’t pass our stricter regulations (especially with our modern pollutants), but it seems that didn’t stop the city.
It’s probably not easy to see this just coming to Venice proper, but the lagoon has quite a set of rivers that come to it or in near areas (the same rivers that “built” the original lagoon, and helped mantain it). So, drought can be fought by using boats that took water a little more into the rivers. Probabaly some 15 kilometers at most from the city center, in very calm waters. They even had, if my memory serves me right, boats of medium size just for collecting waters, probably used even in normal times.
Even now that we have factories and well, surely bathe ourselves more than in that days, water use is more than 80% dedicated to irrigation and themoelectric power, things that Venice didn’t ever thougth of (well, maybe irrigation was thought about, because Venice and the lagoon, oddly for us that see her in this days, did have quite some gardens and kitchen gardens, but of course irrigation was not the issue).
Add to this the fact that alcol beverages were used also because they were often more safe to drink than water just out of the well, or that the water closet was not used (unfortunately for poor early hours travellers, alas!), and the thing is more plausible.
No apologies necessary, good post. (My Italian girlfriend has a number of relatives who despite having lived in the U.S. for many years don’t speak English half as well as what you just demonstrated.)
“After separating most floc, the water is filtered as the final step to remove remaining suspended particles and unsettled floc. The most common type of filter is a rapid sand filter. Water moves vertically through sand which often has a layer of activated carbon or anthracite coal above the sand. The top layer removes organic compounds, which contribute to taste and odour. The space between sand particles is larger than the smallest suspended particles, so simple filtration is not enough. Most particles pass through surface layers but are trapped in pore spaces or adhere to sand particles. Effective filtration extends into the depth of the filter. This property of the filter is key to its operation: if the top layer of sand were to block all the particles, the filter would quickly clog.”
I know that the city of St. Paul is currently replacing their sand filters with more modern equipment. According to the city web site article, the filters are 36 inches of charcoal with 4 inches of sand underneath.
