In order to meet the water needs of its population, the city of
Rome was eventually supplied with 11 aqueducts by 226 AD, which were some of the city's greatest engineering achievements. Estimates of total water supplied in a day by all aqueducts vary from to , mostly sourced from the
Aniene river and the
Apennine Mountains, serving a million citizens. Most of our information about Roman aqueducts come from statistics compiled in the late 1st century AD by
Sextus Julius Frontinus, the
Curator Aquarum. These estimates may not have considered water loss. Modern engineers have questioned the validity of these figures and measured
Anio Novus limestone deposits to estimate the average
wetted perimeter and
surface roughness corresponding to only 2/3 of the flow figure given below. == See also ==