First off, it is a standard sized water filter housing and second, you should have a water filter wrench lurking about in your wet bay somewhere. If you can't find the filter wrench, you can get one at Lowes or Home Depot.
Your water filter housing may or may not have a pressure relief button on top of the housing. If it does and with the water off, push the button. If it doesn't, just turn off the water and open a faucet to depressurize the system. Put the wrench on and loosen the housing. Once loose, you can just unscrew it by hand.
If you are not using an external filter system, the filter is a standard combination (particulate and carbon) filter that you can get almost anywhere - including Lowes and Home Depot.
Roger & Mary
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