In putting together an outdoor survival kit for urban use, you can pretty much use many of the same items you would use for any outdoor survival gear bag. You need water and a means to purify it and you must have some sort of food in your bag, even if it’s just a couple days worth of something. A light source would be useful, a pair of gloves to protect your hands and some way to keep you dry.
How do you plan on carrying you stuff? Would this be for your car or do want to keep a backpack that you could take with you everywhere you went, in the car and out. That may be the beast way to go, or if you have the money you could make two or three kits. You could keep one in the vehicle, one to carry and preposition one at your job if there is a safe place to keep it. It may sound like a lot of stuff to worry over but what if you could not get to one kit, you would have some back ups.
Whatever you put into your bags is to be for that bag only. No borrowing items for camping trips or whatever because you may never put it back where it belongs. Any food you have in your bag needs to be checked on occasionally to make sure something has not expired or gone bad. Any medicine you have in your first aid kit also has expiration dates so keep up on that also. Don’t keep batteries in your flash lights until you need them, the batteries will loose their power sooner and if they go bad they will leak inside your flash light.
Do you prepare for what may happen unexpectedly? You can never know when some unforeseen incident will catch you off guard. For more information on urban preparedness go to this survival preparedness site and you will find some of the best book resources available. Learn all you can about being prepared for the future.