The windshield washer reservoir holds the washer fluid until you need it for your windshield. However, if after filling up your Ford Focus' reservoir you discover there isn't any fluid, you can deduce that you have a leak and need to either fix or replace the reservoir. You can either replace the windshield washer reservoir in your Focus yourself or take it to a mechanic.
Order a new reservoir to replace the old one from the parts supplier for your Ford Focus. Some dealerships have parts available for purchase or they may have a replacement reservoir in stock; otherwise, ask them to order one for you.
Turn the car off and remove the keys from the ignition. Pull the hood release handle beneath the instrument panel of your Focus. Exit the car, walk around to the front, reach under the center of the hood and locate the auxiliary release latch. Twist it to the left to open the hood. Hold the hood open using the prop rod on the engine compartment's edge.
Locate the windshield washer fluid reservoir, which is next to the battery near the right edge of the Ford Focus' engine compartment.
Remove the left front fender line and fender in order to get to the windshield washer reservoir in your Focus. To do this, unscrew the three or four bolts on the top that are visible with the hood open and the couple under the front of the car where the front bumper cover and the fender join.
Take off the headlight and you will have one more bolt to unscrew near the firewall. This will give you complete access to the windshield washer reservoir. Remove the hose and any other leads and unscrew the tank. You should then be able to lift the reservoir out of your Focus.
Screw in the new windshield washer reservoir to install it. Reattach the hose and other leads including those attached to the electrical system, and replace all the seals. After that is complete, reassemble the headlight, fender line and fender by reversing the order starting in Step 5 and continuing in Step 4.
If you're driving a 2008 or 2009 Focus, the windshield washer reservoir is on the other side of the compartment to the left of the engine coolant reservoir. Check for a crack in the reservoir that might be repairable. To increase your chances of finding the leak, pour some washer fluid into the tank.