There is a lot of construction under way in Cairo, including major work on the water and sewer systems, so some damage to the water mains may occur from time to time, allowing seepage of sewage into the drinking water. Also, if the water in your building or neighborhood goes off for some hours, the water sitting in the pipes may absorb impurities. For these reasons, or if the water runs discolored from the tap or leaves a sediment, it should be boiled for 15 minutes, then stored in sterile bottles. Soft drinks and beer are safe to drink as long as they are bubbly, but avoid flat soft drinks and beer because this could be a sign of contamination. Avoid ice cubes that may have been made from contaminated water.
Pasteurization destroys the bacteria in milk that cause tuberculosis.
Locally-produced yogurt should be safe if it comes in a sealed container. As a general rule, it is best to avoid salads, especially lettuce. If preparing a salad yourself, wash all ingredients thoroughly. Tomatoes can be peeled by submerging them in boiling water for up to one minute, then slipping the skins off. Lettuce is hard to sterilize - many doctors recommend not eating it at all.