If you have an under sink water filter, the filter will need to be changed every now and then. It isn't a difficult job, and can be done in just a few minutes with the right tools.
Before you start this replacement, you will want to make sure you have everything you need at your hands. This will prevent you from having to leave the sink area to grab tools you may have forgotten. Check the sink filter before you purchase the replacement. The filters may vary from model to model. Have some towels handy to soak up water that may leak from the lines during the replacement. A sump wrench should have been included with the initial filter purchase, you will need this. If you have misplaced it, you can purchase a replacement when you purchase the new filter. Some models also require a silicone lubricant, so be sure to have this handy, as well.
Turn Off Valve and Drain
You will need to turn off the cold water valve before you start anything. The turn-off can be found under the sink itself. Once the valve is closed you will want to lay down the towels you brought. Release the pressure from the lines by turning on the faucets for both the hot and cold water. Your filter model may also have a vent valve that needs to be pressed. This will release the excess water in the filter unit itself.
Remove the Filter
With the lines drained and the pressure released you can begin to remove the old filter. Use the sump wrench to remove the sump by turning it clockwise. The sump will likely have water in it, so be sure the towels are in place to catch this. Remove the O-ring seal and put it aside. You will need this again later. Remove the old filter and toss it in the trash. The sump itself should be removed and cleaned in soapy water. Do this in another sink, like a bathroom sink, and be sure to get all of the excess soap out of it before moving on.
Replacing the Filter
Follow the manufacturer's directions to replace the filter in the sump. Most often the filter will just need to be placed in the sump and pressed down until you hear it click. Use the silicone lubricant on the O-ring and set it in its groove. Be sure it's in the right place and secured. Line up the filter head and the sump, and tighten it by turning it clockwise. Write the date on the label provided so you know when to replace it the next time. If there is no label included, you can write the date on the side with a marker.
Turn the water valve back on. Slowly open it to fill the filter. If your model has the vent valve, be sure to hold it down so air doesn't get in to the unit. Check to be sure there are no leaks. Let the water run for about 5 minutes to remove any carbon particles from the filter.