When it comes to water filter cartridges, 2" x 10" is the norm and available everywhere. 5 micron carbon block is what you want. It is important to note this type of filtration will not remove harmful bacteria so the shock treatment is mandatory, this will remove all odour/taste issues plus filter particulate matter down to the micron size of the cartridges used. The units in the picture are made by Watts and have a built in valve which does filter/off/bypass however any unit will do. Quite a few ways of mounting these and you may need to become creative as each apllication is different. Mine are located in the galley floor storage. I used 2 in series although not required I tend to overdo things.

How to shock treatment.
Do this by adding around 2-3 cups of bleach to the water tank, then fill completely. Once full open every tap to get the bleach water into the line. Once all taps have been addressed top of tank until you get water coming out the overflow. Let this sit and do its thing until next morning. Flush, fill and empty the tank at least a couple of times to remove bleach smell. This should be done with old filters or no filters in place. In my case I just select the bypass position.
reason lines are filled and allowed to sit is they also contribute to bacteria/mould growth so they need to be treated also, not just the tank. I prefer to winterize my lines with pink stuff since I figure there will be less growth in there if they are full of pink as opposed to damp after a blow job.

