Use a pencil to mark the area on the brick or block on the inside of your house where you first saw the water. Follow the trail of water as far as you can, back to where it may have originated and check for a leak there.
Inspect the areas around all windows and doors that are installed in brick. Check that they are properly sealed with silicone or caulk on both the inside and outside of the house. Look for gaps between the window and the brick on both sides.
Check for leaks where the house meets the foundation. This is a common area for there to be gaps in the brick or block. Go around the entire house on both the inside and outside. Run your hands over the surface to check for any leaks.
Press a digital moisture meter up against different areas of the wall. The moisture reading will vary, depending on the location of your house. Move the moisture meter around different areas on the inside of the house and look for a reading that is extremely high and stands out compared to the other areas.
Search the areas with the high moisture meter readings for the cracks until you find them.