The government on Friday announced emergency action as parts of the country appeared - despite long-awaited rain - to be heading into an early drought.
Environment Minister Alfonso Pecoraro Scanio stressed, however, that the state of emergency called in central and northern regions was "precautionary" and the rainy spell might change the outlook.
Cabinet Undersecretary Enrico Letta said current Civil Defence reports were "reassuring".
Letta said contingency plans, mainly for the farming and electrical-power sectors, would be lined up next week.
Experts have warned that despite the arrival Thursday of torrential rain - forecast to continue for the next three days - the north's key River Po was still much too low for this time of the year.
Central and northern areas had 20-50% less water than last year, they said.
Action was needed, the government said, to avert damage to agriculture and power outages.
A crisis unit meeting earlier this week called for restrictions on water use for non-domestic purposes like irrigation and power generation.
The experts said it was essential to keep the Po at the highest level possible, if necessary by "opening the taps" of higher mountain lakes to send water into the river.
The 675 km-long Po, the country's longest and most used river which cuts across the north from west to east, feeds irrigation channels and industries on the fertile Po plain and is also a major shipping route.
The river has been hit by drought several times over the past few years but never this early in the season.
On April 22 the river hit an unprecedented April low of 6.53 metres below sea level.
Thursday's downpours, however, swelled it by a remarkable 1.5 metres in 24 hours - but farmers said it was a "temporary respite".
The north's Lake Garda, the largest lake in Italy, has also been affected and is 50 centimetres below its normal level in places.
Italy has just emerged from the mildest winter on record.
The summer ahead is expected to be dry with temperatures at least one degree higher than the average for the past five years.
Electricity shortages could occur unless preventive action is taken, the government says - as rivers and lakes feed much less water than usual to power stations unable to cope with extra demand from air conditioners and refrigerators.
