Mini expansion device for portable water

[Another John]

You never heard of portable water? I was sold a large pack of it a few years ago, which I've kept in case of emergency: it's dehydrated, and when you need it all you do is add - um ...

J.

[Johnny B Good]

... water, preferably of the potable kind (like what you can draw off the public main supply in most parts of the UK, usually from a kitchen sink cold tap) if you wish to rehydrate yourself.

Plastic lemonade bottles with screw caps can be recycled as 'dehydrated water' readily hydrated from any kitchen cold tap or other potable supply you might find on your travels.