How do you store enough emergency water in limited space?

[Whatarewedoing]

We are a family of four and live in a town with three decent size supermarkets, one in walking distance. We are limited for space, but I have been building up our non perishable food supply to last us two to three weeks. The thing I have not got a handle on is water - arguably the most important of all. If we need 3 liters drinking water a day per person, 10 to be comfortable, that would be an enormous amount of bottled water. We dont have that storage. If you feel you have a good handle on your emergency water prep, what do you do? Are there any special storage containers or even filters that you can recommend? How long would you prep for given my situation.

In an emergency it is only 1.5-2 litres per day min which is pretty much enough for drinking and a quick flannel wash. So i would just focus on 3-5 days of bottled water for drinking.
Do you have water butts? They could be used for water for flushing loos. Could you store any bottled water outside? It doesnt need to be kept dry although it could break the bottles if it freezes.

You don't need that much drinking water. You can use rainwater for example for washing.

2 litres per person per day is plenty for drinking and cooking.

And if necessary I would cook with rainwater, if it was boiled.

3-4 large containers is plenty, have uht milk for children if applicable and cartons of long life juice too

We have water butts outside, holding approx 1000l all told but not everyone has outside space. I'd use that if I needed to, water purification tabs if for drinking or cooking. Indoors we use washed out large milk containers to store tap water, I see no need to buy bottled when already paying for my water meter. Then I use this for cooking, boiling etc and just keep refilling so its always reasonably fresh. I store it in odd cupboard spaces. My friend actually stores some behind her bath panel 😅 but we don't have a bath. We also have a few of the collapsible 5l containers, and they're stored in the shed.

No idea , we have a small holding.

Inside one of those garden storage benches, the ones that contain the cushions for the garden furniture etc. They've got lots of depth and room, and close at the top too, and don't look out of place either somewhere in the garden.

I'm of course presuming you have a garden! If not, under the bed in those storage boxes with wheels that you can pull out easily. Shove what's already under the bed into the attic/loft.

Pop, fruit juice and plant/uht milk all count for drinking.

You keep clean with wet wipes, hand gel and minimum water for hand washing flannel bath. (Bits and pits everyday)

Loo: bucket, bin bag and cat litter. Wee can go on a compost heap if you have one. (Bob Flowerdew's recycled beer. Or in the loo. It will just trickle over the u bend.

Store water under beds, back of wardrobe under kitchen units, behind the bath panel.

Learn how to filter and purify water by boiling.

Water purifation tablets. Collect rain water in clean containers.

Water butt for plants.

If you store jam jars, fill them with water , it takes up the same space.

Life straw.

We have one of these to filter water: https://amzn.eu/d/06ec0iSY

Useful for camping as well as prepping.