The flood pools will be built near low-lying traffic passages that are most vulnerable to flash floods.
Many of the existing passages are dilapidated and because of their location are frequently inundated in the rainy season, officials with Beijing's water supply bureau said today.
The pools are expected to be completed before summer next year.
The main concern will be avoiding underground pipes, subway lines and building foundations while building the pools, state news agency Xinhua quoted the officials as saying.
Beijing was battered by the heaviest rain in six decades on July 21. The government put the death toll at 79 in its latest tally.