Scrape away large areas of efflorescence, or white powdery buildup, using a wire brush.
Fill a bucket with water and add about two pounds of TSP, or tri-sodium phosphate.
Spray the brick surface with a hose and a spray nozzle.
Dip a nylon scrubber with an extension handle into the TSP solution and use it to scrub the bricks. This solution will remove most brick debris and stains without harming the surface. Rinse the brick and allow it to dry.
Scrub the brick with a diluted, acid-based brick cleaner if water stains have developed near the bottom from sprinklers or other prolonged water exposure. Again, rinse and let dry.
Chip away crumbling mortar between the bricks with a chisel and hammer.
Spray the mortar with water using a spray bottle. The mortar just needs to be a little damp.
Trowel on new mortar and pack it in place with the back of the trowel. Scrape away the excess first with the trowel and then with a stiff brush.
Continue moistening the new mortar for about four days. If it stays moist, it will cure better.