At the time of European settlement the river was a summertime chain of waterholes bounded by large gum trees.
Flowing through the area where the city of Adelaide is sited the river was sometimes invisible beneath its gravel stream bed.
It frequently flooded in winter and did not reach the sea, instead ending at coastal dunes where its waters created a vast but shallow freshwater wetlands.
These wetlands, known as The Reedbeds after the dominant vegetation, occupied a large area of the western Adelaide Plains and were also fed by other waterways.
The river only flowed to the sea through the Port River, Barker Inlet, and Patawalonga River following heavy rain.

The river's catchment area of approximately 500 km² (193 sq mi) is the largest of any waterway within the Adelaide region.
The upper reaches are used to create a potable water supply for metropolitan Adelaide with the river supplying three of Adelaide's eight reservoirs.
The upper catchment has an average annual rainfall of between 575 millimetres (22.6 in) at its eastern end to 1,025 millimetres (40.4 in) near Uraidla.
The Torrens has a very variable flow leaving early settlers to use trial and error in determining bridge heights, with many bridges consequently being washed away.
Due to the variability of Adelaide's climate, flow rates can change from a trickle to flood conditions quickly.
On 5 June 1889, prior to major flooding, the flow rate before it entered the suburbs was 0.7 cubic metres per second (25 cu ft/s), rising to 129.1 m³/s (4,560 cu ft/s), eight days later.

What the River Torrens may be capable of performing for a week or two of the rainy season beyond sweeping down to the swamp the summer filth of Adelaide we cannot guess; but the Torrens at other times is not a river at all, but merely a chain of fresh water pools.
At the present moment, its running water may be spanned with the hand and sounded with the forefinger
— The Register, 1838
Since settlement it has repeatedly flooded, sometimes with disastrous consequences.
Adelaide's western suburbs were especially prone to flooding due to their location on the river's alluvial fan.
As development of Adelaide progressed the amount of rainfall required for flooding decreased and consequent damage increased.
Increased stormwater runoff, modification of the river's banks and other changes all served to exacerbate the problem.
Work done by various groups to minimise flooding was often counter productive with the creation of levees, moving and widening channels and other works simply shifting the flooding elsewhere.

Two early floods were, 18 September 1841 which resulted in two people drowning while trying to cross the river at Klemzig, and 22 September 1844, the largest recorded since settlement began, when "Shands' Brewery" was washed away after the river undermined its foundations.
The 1899 flood was particularly widespread with extensive flooding of both the river and its tributaries, after a year with 785.6 millimetres (30.93 in) of rain compared to the Adelaide average of 530 millimetres (21 in).
The river flooded market gardens and farms throughout its hills course causing extensive damage.
Norwood was inundated to The Parade, Adelaide to Pirie and Rundle Streets, and many areas west of the city were left in a shallow lake.
The river ran 9 feet (2.7 m) deep over the weir near Thorndon Park Reservoir, 3 feet (0.91 m) over the Torrens Lake Weir and 1-foot (0.30 m) over the Morphett Street Bridge.
The Underdale (or Holbrooks) Bridge was destroyed, the Torrens Lake weir's bridge damaged, and the Felixstow Bridge over the Fourth Creek washed away.
At the time of European settlement the river was a summertime chain of waterholes bounded by large gum trees. Flowing through the area where the city of Adelaide is sited the river was sometimes invisible beneath its gravel stream bed. It frequently flooded in winter and did not reach the sea, instead ending at coastal dunes where its waters created a vast but shallow freshwater wetlands. These wetlands, known as The Reedbeds after the dominant vegetation, occupied a large area of the western Adelaide Plains and were also fed by other waterways. The river only flowed to the sea through the Port River, Barker Inlet, and Patawalonga River following heavy rain.
The river's catchment area of approximately 500 km² (193 sq mi) is the largest of any waterway within the Adelaide region. The upper reaches are used to create a potable water supply for metropolitan Adelaide with the river supplying three of Adelaide's eight reservoirs. The upper catchment has an average annual rainfall of between 575 millimetres (22.6 in) at its eastern end to 1,025 millimetres (40.4 in) near Uraidla. The Torrens has a very variable flow leaving early settlers to use trial and error in determining bridge heights, with many bridges consequently being washed away. Due to the variability of Adelaide's climate, flow rates can change from a trickle to flood conditions quickly. On 5 June 1889, prior to major flooding, the flow rate before it entered the suburbs was 0.7 cubic metres per second (25 cu ft/s), rising to 129.1 m³/s (4,560 cu ft/s), eight days later.
What the River Torrens may be capable of performing for a week or two of the rainy season beyond sweeping down to the swamp the summer filth of Adelaide we cannot guess; but the Torrens at other times is not a river at all, but merely a chain of fresh water pools. At the present moment, its running water may be spanned with the hand and sounded with the forefinger
— The Register, 1838
Since settlement it has repeatedly flooded, sometimes with disastrous consequences. Adelaide's western suburbs were especially prone to flooding due to their location on the river's alluvial fan. As development of Adelaide progressed the amount of rainfall required for flooding decreased and consequent damage increased. Increased stormwater runoff, modification of the river's banks and other changes all served to exacerbate the problem. Work done by various groups to minimise flooding was often counter productive with the creation of levees, moving and widening channels and other works simply shifting the flooding elsewhere.
Two early floods were, 18 September 1841 which resulted in two people drowning while trying to cross the river at Klemzig, and 22 September 1844, the largest recorded since settlement began, when "Shands' Brewery" was washed away after the river undermined its foundations. The 1899 flood was particularly widespread with extensive flooding of both the river and its tributaries, after a year with 785.6 millimetres (30.93 in) of rain compared to the Adelaide average of 530 millimetres (21 in). The river flooded market gardens and farms throughout its hills course causing extensive damage. Norwood was inundated to The Parade, Adelaide to Pirie and Rundle Streets, and many areas west of the city were left in a shallow lake. The river ran 9 feet (2.7 m) deep over the weir near Thorndon Park Reservoir, 3 feet (0.91 m) over the Torrens Lake Weir and 1-foot (0.30 m) over the Morphett Street Bridge. The Underdale (or Holbrooks) Bridge was destroyed, the Torrens Lake weir's bridge damaged, and the Felixstow Bridge over the Fourth Creek washed away.
River Torrens