How to change a water filter cartridge

[Trac]

I was wondering if anyone can give me simple instructions of how to change an Acquifier water filter cartridge?
I believe I have to turn the water off first, under the sink, and need to locate a quarter turn valve.
I was wondering if anyone can help me locate this valve or a point under the sink where I switch off water so I can replace the cartridge.
I assume I also need to switch off the mains water point.
H ere is an image of under the sink - the think blue piping leads to the cartridge that needs to be replaced.
Thank you!

 

[Ben-gee]

It will be fed from the mains water supply, so just turn that off if you can’t find a valve locally. Either st your stopcock or out in the street.

 

[ShaunCorbs]

You can try turning the washing machine valve off that feeds the filter sometimes they work sometimes they stick if not as Ben says mains off etc

 

[Harvest Fields]

You can try turning the washing machine valve off that feeds the filter sometimes they work sometimes they stick if not as Ben says mains off etc

Have some kitchen roll or a bowl to hand to collect the water and open it slowly to see if it has held.

 

[ShaunCorbs]

or open your filter tap and turn the valve off if it stops your good to go as harv says have a towel ready for any drips etc

 

[Trac]

Many thanks all. This is really helpful. I shall try the suggestions and certainly turn off at mains. I can't see anything understeer sink that I would need to switch off. I assumed I would need to turn off a valve here but don't know what I'm looking for....I hope that turning off at mains would suffice and then do a quick filter replacement. ..

 

[JCplumb]

The isolation valve is right there, middle left on the pic. It's a tee with a blue handle.

 

[Trac]

That's really fantastic JC. Brilliant . Many thanks. It's much appreciated. I shall give the valve a turn bit will switch off at mains as extra precaution.