What you store your water in is important for water safety. You will need a container that can be made airtight and doesn't let any light in. That will solve two of the biggest problem. A 55 gallon blue water storage barrel is the perfect solution. It is safe for food or water storage, is opaque and can made airtight.
Now that you have the right kind of container, you need to treat the tap water before storing it in the barrel. Remember all water has bacteria in it. so we need to pre-treat the water after filling the barrel. This potent and pure form of chlorine will kill bacteria providing you with a long-term 5 year storage? The only product that I know of that is EPA approved is a product called "Water Preserver". It kills all the bacteria in the water and the inside of the barrel leaving you with sterile water for 5 years. The Water Preserver must be used in combination with containers that are not clear and have caps that are airtight.
At the end of 5 years, simply dump the water, refill the barrel with fresh tap water and then re-treat with Water Preserver for another hassle free 5 years of emergency water storage.
CAUTION: Adding Bleach to your water storage is never a good idea or plan, it does nothing to extend shelf life and only contaminates your water. The Environmental Protection Agency (EPA) considers bleach as a pesticide. Bleach can contain mercury and arsenic. I know everyone promotes bleach as a primary way to treat questionable water. I consider it a last resort.
There are many better options before you should have to resort to bleach.
For more info, click on How To Store Water.