Aqua Clopedia, a picture dictionary of Roman aqueducts: Basins

1. A double storage basin (reservoir) on two levels at the end of the aqueducts of Lyon (France) on the La Fourvière hill

2. The famous distrubution basin at the end of the aqueduct of Nimes (France)

3. A junction basin in the Köln aqueduct (Germany) near Eiserfey. The main channel came from right, a tributary came from the front; at top left the common outlet

4. A regulation basin in the aqueduct of Nimes, near Uzès. Surplus water could be diverted to the river nearby (top left)

5. A basin near Ars-sur-Moselle (France) with a settling facility (bottom) at the begin of the aqueduct bridge over the river Mosel towards Metz

6. Drawing of a water collecting basin near Kalmuth, part of the Roman aqueduct of Köln (Cologne, Germany)

7. The header tank of a siphon in the Gier aqueduct of Lyon (France). The inlet was on the right (backside), in the front a series of openings for lead pipes. An example of a transition basin

9. A street-side basin (fountain) in the streets of Gerasa (Jordan)

Home

Aqua Clopedia

FAQ on aqueducts

January, 2011

Basins

In Roman times the water, on its way between source and city, would have passed bridges, tunnels and/or arcades, but also basins with specific functions, some of them even with more than one function. Apart from the well known distribution basins (castellum aquae), some basins were made for collecting, for settling (cleaning) or to decrease in the velocity of the water flow. The walls of all these basins were plastered and made watertight by means of what is called opus signinum, a plaster made of tiles broken in very small pieces mixed with mortar.

The terminology of the different types of basins is confusing. Here a proposal for a classification:

#	English	Français	Nederlands	Deutsch	Latin
1.	Storage basin	Réservoir	Opslag bassin / reservoir	Wasserspeicher	Piscina
2.	Distribution basin	Bassin de distribution	Verdeelbassin	Verteilerbecken	Castellum divisorium
3.	Junction or Splitting basin	Chambre de puits	Combinatiebassin	Sammelbecken
4.	Regulating basin	Bassin de derivation	Regel- of aftakbassin	Ableitungsbecken
5.	Settling basin	Bassin de décantation	Bezinkbassin	Piscina limaria Absetzbecken
6.	Collecting basin	Puit collecteur	Verzamelbassin	Brunnenbecken?
7.	Transition basin	Bassin de transition	Overgangsbassin	Überleitungsbecken
8.	Waterfall (with stilling basin)	Chute de l'eau (avec un bassin d'armortissement)	Waterval (met woelbassin)	Wasserfall mit Tosbecken
9.	Street-side basin	Bassin de fontaine	Fonteinbak	Schopfbecken

For more examples, drawings and photo's, see the subsite.

1. Storage basin

Cistern in the desert of SW Jordan

To store aqueduct water in order to absorb fluctuations in the water supply and discharge. Illustration 1. (top of page) shows a multiple chamber basin with connecting corridors and a drain (not visible) on the La Fourvière hill in Lyon (France); the visible chambers are the two lower parts of this four chamber basin.
A cistern is often related to a basin to store rainwater. It was part of the 'standard' Roman house and found under the implusium.
Cisters were (and still are) common in arid areas with long dry seasons, mostly around the Mediterranean Sea.

2. Distribution basin

In classical as well as in modern literature the distribution basin (in Latin: castellum divisorium) received most attention. In most cases it was the end of a gravity flow aqueduct, located in the upper part of a town or villa. From that place the water was distributed by means of lead or terracotta pipes to the custumers. In some cases the water was subdivided in second order castella and from there on it ran to the customers.
During the reign of Augustus Vitruvius, an army officer and architect, wrote a handbook De Architectura inwhich he described a prototype of a castellum (book 8, chapter 6 1b - 2). It reads:

1.b When it [the water] has reached the city, build a reservoir with a distribution tank in three compartments connected with the reservoir to receive the water, and let the reservoir have three pipes, one for each of the connecting tanks, so that when the water runs over from the tanks at the ends, it may run into the one between them. 2. From this central tank, pipes will be laid to all the basins and fountains; from the second tank, to baths, so that they may yield an annual income to the state; and from the third, to private houses, so that water for public use will not run short; for people will be unable to divert it if they have only their own supplies from headquarters. This is the reason why I have made these divisions, and also in order that individuals who take water into their houses may by their taxes help to maintain the conducting of the water by the contractors.

Unfortunately a castellum based on this principle has never been found by archaeologists.

Agrippa was the first 'manager' of the waterdistribution in Rome (in Latin: curator aquarum). One of his successors was Frontinus during the reign of Nerva and Trajanus (appr. 100 AD). He wrote a book on the nine aqueducts of Rome at that time "de aquaeductu urbis romae" in which he mentions 247 (first and second order) castella (distribution basins) in Rome alone (chapter 78).

Aqueduct	# of castella
Aqua Appia	20
Anio Vetus	35
Aqua Marcia	51
Aqua Tepula	14
Aqua Julia	17
Aqua Virgo	18
Aqua Alsietina	0
Claudia / Anio Novus	92
in total	247

First order distribution basins have been found in Nîmes (France) - see illustration 2. above - and in Pompeii (Italy). Both are quite different in lay out and do not reflect the description of Vitruvius. A third could be found in Rome untill 1880, quite close to the Porta Maggiore. It was the terminus of both Claudia and Anio Novus aqueducts. At the end of the nineteenth century this basin was used as hay-barn and unfortunately caught fire. Piranesi made a fine drawing of the exterior of this castellum. In 1934 Van Deman described it as follows:

No remains are now traceable of the terminal reservoir, which lay about a hundred meters southeast of the Nymphaeum commonly known as the temple of Minerva Medica. An excellent engraving, however, was fortunately made of it by Piranesi before its almost entire destruction by fire. According to the plan of Lanciani, by whom some broken fragments were identified some decades ago, it measured on the outside 21,50 m. long and 14,20 m wide, and was divided into five chambers. The construction of the walls, so far as can be determined from the engraving of Piranesi, was of cut-stone with vaults of concrete (Van Deman1934).

An other castellum is still present in Rome called "Trophies of Marius", the more official name is Nymphaeum Severi Alexanderi. It was a munera, an ornamental fountain in combination with a distribution basin. Archaeologists do not know for sure whether the water came from the Aqua Julia or the Aqua Anio Novus, see the subsite Rome. Its impressive remains can still be seen at the Piazza Vittorio Emanuele II.

There are also some rare preserved examples of castella of the second order, most of them in Pompeii. They looked like water-towers and were necessary for reduction of the water pressure caused by the slope of the terrain.
Especially in North Africa more castella divisoria can been found, all at the terminus of an aqueduct but not every basin transferred its water into pipes of lead or terracotta as for example if the destination was a cistern or a bath house (thermae). Unfortunately details of the original construction are often lacking when they are brought to light.
For an overview of some other castella divisoria see the subsite.

6. Collecting basin

There were different ways Roman aqueducts tapped their water sources: river intakes, dams, infiltration galleries, well intakes and spring boxes (see Source). In the last two cases the water was collected in a impermeable basin, the start of the aqueduct conduit, in most cases followed by a settling tank to get rid of debris. Well intakes usely tapped the groundwater while spring boxes were made to curb the active spring. The best researched collecting basins are the ones of the aqueducts of Nîmes (Fountaine d'Eure, France), Cologne (Klausbrunnen, Germany, see illustration 6. above), and Sens (Noé, France).