Some newer homes will have a central water filter and conditioning system installed. These central units filter all the drinking water prior to it being delivered at the faucet. It is important to understand how your unit operates, and to remember what frequency you need to either replace filters in the unit or clean out any fixed filters that come with the system.
You must read the owner’s manuals for the specific house water filtration system you have. Make sure you follow these instructions in order to change out any filters on a regular basis.
The basic principles of maintaining the system is water is being filtered by one, two or maybe even three different filters before delivering water to your home. Changing the filters requires shutting off the water supply valves on both sides of the filtration system and bleeding out the pressure in the existing lines.
The filters are inside long vertical canisters that can be un-screwed from the bottom. Make sure you have a bucket ready to catch some of the water that will spill out. Remove the old filter and make sure there is no debris in the bottom of the canister. Insert the new filter.
Some units have O-ring seals that should be lubricated with food based silicon grease. Check your manufacturer instructions on this piece. After lubricating the O-ring and the threads where the canister gets connected, screw the canister back onto the housing. Open the valves after and before the system to re-engage the water supply. You might want to run the water for a few minutes to flush the system.
Here is a great overview video from Aqua Man Wisdom.