Congregados Reservoir

The Congregados Reservoir, one of the most important water supply tanks in Porto, was built in the late 1880s to serve the city’s higher areas. Located on the Monte dos Congregados, the highest point in the city at 158 metres above sea level, it was a semi-buried masonry reservoir divided into two independent compartments, with a total capacity of 3935 cubic metres and a water level at 160.80 metres. Initially, it was supplied by steam-powered pumps drawing water from the Santo Isidro Reservoir approximately 200 metres away, with a 36-metre level difference.

With the city’s population and urban growth, the reservoir’s capacity became insufficient. In 1934, plans for raising the tank were made, and by the early 1940s the Torre – Congregados Reservoir was built, with a capacity of 500 cubic metres and water level at 180.80 metres, intended to maintain network pressure rather than provide additional storage. To reduce operating costs, water was pumped directly from Santo Isidro to the tower instead, from 1949 onwards.

In the 1950s, construction began on a new complex comprising four stepped circular tanks. The first was built in 1953, following the demolition of the southern chamber of the old reservoir, using the “Blaton-Magnel” technique, advanced for its time. This was followed by the second reservoir, constructed between 1956 and 1957, incorporating “Freyssinet” prestressed cable systems. The third, a 10,000 cubic metre prestressed concrete reservoir, was completed in the late 1980s.

Today, the three circular reservoirs manage water supplies for the upper city, feeding the distribution network during peak demand and storing water during low demand. The largest 10,000 cubic metre tank also functions as a pumping well for the lift station serving the city’s upper zone.