How to replace a water filter cartridge on your home water filtering system. This article covers how to change both filters on a Aquasana AQ4000 filter system.
Some of this information may be helpful with any brand of filter system. Unpack the replacement filter kit and check the contents. You should have 2 replacement water filter cartridges, A and a B. Two replacement O-rings. If the O-rings are not flat lay them out and see if they will flatten out on their own this may take over night. If this does not work, put a book on them over night. The reason is if the O-rings are bound from shipping makes then harder to make a good seal.
The first step is to lay your home water filtering system on its side. You can see on the filter caps are labeled A and B. Also arrows that indicate which way to turn to loosen each cap. Turn filter cap A to the right to unscrew or the direction the arrow points. Filter cap B should unscrew to the left or the direction of the arrow. They should only be hand tight. If they are too tight to remove by hand use the handles of a pliers to give you a little extra leakage. Be careful not to do any damage to the inlet or outlet water lines.
Water filter cartridge A will be the most difficult to remove. The seal on the top of the filter holds the cartridge in place. There is not enough room in the filter housing to get a hold of it. I find it easy to use a pair of pliers to get a hold of the filter and twist and pull to it out. Water filter cartridge B will be attached to the filter cap. Simply twist and pull the two apart. I lay the filters at each side of the filter housing. This helps to keep track of which filter is A and B. Remove both o-rings make sure the grove where they sit in is clean. Now install the two new O-rings. Put a small amount of food grade silicone based lubricant on the exposed area of each O- ring. This helps when installing the filter caps. The oil lets the caps slide easy on the rubber, which will make them seal easier. Installing them dry may let them kink and dislodge result in a leak.
Replacement water filter cartridge A is the white one. Install it in the A cartridge housing with the O-ring end in first. Putting some water on the rubber seal makes it slide in easier. Give it a push and turn until it is sorted. The B replacement cartridge is the blue one. Install the O-ring end into the filter cap. In the same manner as the other filter. At this point, I check the O-ring to make sure they are still in place. Then go ahead and install the B filter into the B housing. Screw the B cap until it is firmly seated. Now check the other seal and install the A cap until it is firmly separated.
Keep the filter system on its side, turn on the water and activate the diverter valve. Check around the cap threads for any signs of water. If there is a little leak, try tightening the cap a little more. If this does not seal the leak, then open up that cap and check the O-ring it may have come out of its seat. Check to make sure it is not cut or damaged. If it is, the old O-ring might reseal. The other option is take one of the old seals to your local hardware store and match it up. The other step if none of these ideas work is to order a replacement seal. Now you can be reinstalled the cap as described above and check for any leaks.
If you do not see, any leaks set the AQ-4000 up right and leave the water run for about 2-3 minutes until the water runs clear. The water at first may come out cloudy or even have a black color, this is normal. Carbon dust is being cleaned out of the new filter cartridges. I save the water that used to flush out the filter system. Houseplants like the water, or put it on plants out side. To keep track of when it will be time to reinstall your next set of water filters. Write the next replacement date on a piece of tape and put it on the filter. This helps to keep track of time. They should be replaced every 6 months or 500 gallons on your home water filtering system.