How do I install a drinking water system in cramped cupboard?

[jacket]

I want to install a drinking water filter system under my sink but it looks very cramped and I don't know which pipe to take the water from. Can anyone advise please?

I was planning to use this Everpure filter but I'm happy to use another if this is too fiddly:

https://best4purewater.co.uk/everpure-bw100-under-sink-filter-system-857.html

 

[jacket]

Here are two close up photos of the configuration...

 

[PlumbGate]

Take water from the cold with a vampire tap. Put the hot on and feel which pipe gets hot if you are unsure which one is cold. Looks like plenty of room for a basic filter. Probably could fit at least a 2 filter system. Not sure there is room for a holding tank though so probably can't do a reverse osmosis system.