One of the things, if not THE #1 thing, we should be most concerned about storing for emergencies is water. I'm dangerously, woefully behind on realistic water storage, so this is my current area of research.
We live in a very small home (450 sq ft? 3 people, 2 pets) and storage is a difficult, continuous issue. Some things I can squeeze into little nooks and crannies. Some things I can repackage or redistribute to save space, but water is water, and you can't compress it, and you can't squeeze it into the cracks. Yet, it's vital to have it on hand in an emergency.
You need water available, independent of "the grid", municipal, or shared sources. Shoot for outdoor tanks. Water catchment would be awesome. You can survive if you have a 1500 gallon tank outside, but can you access it? If you're in an emergency situation things are already uncomfortable and strange. Wouldn't it be nice if you planned ahead so that the most mundane tasks don't turn into an additional burden?
The general rule is to have 1 gallon of water per occupant per day. That adds up, and I think that's a conservative estimate. Multiply your daily use by how many days worth you would feel best about having on hand and you'll see, it adds up fast.
That 1 gallon rule probably just means drinking water. You will NEED water for sanitation and hygiene. It's really not optional. Hand washing, dishes and even showers are important, and become more important the longer the emergency situation drags on.
There are lots of reasons to have, and ways to stash, emergency water, but have you considered how you will access it? If you have barrels outside or some other way that you store larger quantities of water, do you have a way off accessing it with relative ease if you need it? Have you ever siphoned before? It's not hard, but have you done it? If you need to, can you do it? Can you pump it? Can you transport it to your house?
One of the pics I added to this post is of a product called Water Bricks. I'm NOT promoting them. Like I said, I'm researching, but I do like the idea and the design. There are lots of different kinds of products on the market for water storage, some are cheaper, some just as good, some just cheap knock offs, different sizes, etc... I chose to picture these because of their ready-to-go functionality. By observation alone I can see:
A. They stack neatly and interlock securely.
18.5 x 18.5 x 18.5 inches ; 18 pounds
B. They hold 3.5 gallons per unit, which makes them portable. Incidentally, most toilets will flush with less water than that... just thinking out loud here.
C. They seem well constructed and durable.
D. You can get an optional spigot to fit the opening. Big plus.
This last feature would be great in the kitchen. Think about it. If you've ever done any primitive tent camping where there's no running water and you didn't have a faucet, you instantly understand what a benefit it would be to sit one of these blocks along side the kitchen sink.
There are some good looking, but costly and bulky equipment you can get for camp kitchens and water, etc... but it wouldn't be practical in a house. I've tried to figure out how to fashion a similar system and adapt it for indoors in case of emergency. Think about a camp shower. The pic I chose was the cheapest, simplest one I saw. They are very portable, lightweight (when empty) and stowable. You pop them out of the box, hang them up, and you have a gravity fed faucet.
Speaking of a camp shower, after a few days without water you will be pretty gritty and grim. It won't kill you, but "survival" would be nicer with a few simple preps. Hang one in your shower stall, or outdoors in a tree, rig a curtain... You will be surprised how good a shower will make you feel, and how morale will improve.
You can buy a pop up shower stall for around 30-40 bucks if you want to go that route. There are even portable propane water heaters for around a 100 (and up). On the cheap end, my husband used to drive for the oil field and he'd be out for WEEKS with no access to showers. He used baby wipes and a 7 dollar pump up, pressurized type sprayer like you'd use for bug spray or weed killer. lol Innovative, but if you're gonna prep for comfort and "homey" familiarity, that ain't it.
I'm just sharing my thought as I'm having them. These things might not be life saving preps, but they are life improving preps, and probably time/labor saving preps. They aren't for your B.O.B. but if you're bugging in through a power outage, a natural disaster or something like that, they're worth a look.
These are just a few considerations concerning water and it's usage in an emergency. Feel free to point out things I've missed that are needful. I'm sure I'm not hitting them all. I need to learn, too.
My 2.
Addendum:
It turns out, the Water Brick also has a water filter that fits in the opening. Like I said, I'm not promoting this product at this point, but it has given me some great ideas. It's pretty cool, and pretty well thought out. You could probably be innovative and McGyver your own equipment if you already have water containers. There's no reason not to just adapt something to them if you have them. I don't have any real stash supplies for water yet, so this is looking pretty inviting. It's a bit pricey, though, all together. I'm going to shop it and see what I could cobble together myself before I commit. Just cogitatin'.