The recommendations for episodes of intense rainfall are:

At home

• Check rooftops, lightning conductors, drainage points and drainpipes, and clear them of any accumulated rubbish.
• Disconnect electrical appliances and remove outside furniture and other items that may be dragged away by water. 
• Keep pets indoors.
• Keep any toxic products away from where water may reach.
• Keep useful items to hand: a mobile phone and charger, essential medicines, clothing and personal documentation.

In the car

• Slow down
• Brake smoothly.
• Stop if you need to.
• Do not cross flooded areas.
• Keep a safe distance from other vehicles.

You can find full safety recommendations on the website for the Barcelona Fire Service.