Want a trek to be organised to reservoir? (5,4)

I believe the answer is:

water tank

I'm a little stuck... Click here to teach me more about this clue!

'reservoir?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?

'want a trek to be organised' is the wordplay.
'to be organised' is an anagram indicator.
'want'+'a'+'trek'='wantatrek'
'wantatrek' with letters rearranged gives 'WATER TANK'.

'to' acts as a link.

Can you help me to learn more?

I've seen this clue in The Hindu.

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