Most people know that when someone is dehydrated they need fluids quickly. But storing Sterile fluids can be tough, most places require a prescription for IV Bags even online. And unless you practice it regularly, sticking people is a perishable skill.
There are much simpler options available. Simply using someone's hydration bladder and an oral re-hydration solution (it doesn't even need to be sterile!) can work just as well as IV administered fluids. Enema Bags are also a good choice if you don't want to ruin a perfectly good hydration bladder
https://www.realfirstaid.co.uk/rectal/