For water storage I use 5 and 8 gallon containers. I rotate them at least yearly, and clean them with bleach and dry them before refilling. I do keep some liquid bleach on hand, and rotate those bottles regularly (annually). I am still prepared to purify the water from these if necessary by multiple methods. I have not stored any chlorine pool chemicals, but have thought about it. Dry keeps longer than solutions or liquids.

That goes for everything stored, dry goods and medicines will keep much longer. Solutions and creams will degrade with time. Dry medicines will also, but we are talking years, and they do not go bad, only lose strength.

Direct sunlight will degrade most materials fairly quickly, especially plastics and synthetics. Everything should be protected from sunlight when stored for extended periods. I once opened a military triangular bandage that had been sitting in the sun in a hot vehicle for a long time (unknown length of time), and it was literally powder. The package was still sealed.

Oxygen and moisture are also enemies of long term storage. Vacuum sealing when possible is good for just about anything. Desiccants are helpful in containers that can be sealed.

Other than protecting from moisture, I am not sure about electronics and batteries. I do keep lithiums for storage and they do need to stay dry. Is there anything special you can do for electronics that are being stored?