I have (2)50 gallon blue barrels in my solid concrete basement. Filled them up 3 years ago with plain tap water. Should I just add the recommended bleach or empty and refill them? Suggestions?
1- make sure that they are not directly on concrete, put boards or wood planks in between. This prevents leaching.
2- empty and refill yearly, add recommended bleach or pool cleaner
There shouldn't be any reason to empty & refill them if they were clean when you stored the water, and the water was clean. Make sure they aren't in the sunlight either. If it makes you feel better, add a little bleach each year as an extra precaution.