Shut off the system by turning off the water supply.
2. Turn off the holding tank valve.
3. Use a filter wrench or by hand to open the filter housing, unscrew it from right to left.
4. Throw away the used filter and clean the inside of the housing by rinsing or scrubbing.
5. Watch for the black "O" ring inside the filter housing ( DON'T LOSE IT! ).
6. Place the new filter inside the filter housing.
7. Place the "O" ring in the housing grove ( MAKE SURE IT IS IN PLACE ).
8. Put some Vaseline or silicon-based lubricant on the O'ring to prevent the bend while tighten the housing.
9. Use a filter wrench or by hand to screw the housing back into place by turning it from left to right ( Don't lay down the unit while screw it in, the unit should be stand upright to prevent the O-ring from slipping ).
10. Observe for any leaks, if there is leak, tighten the housing or re-aligning the O'ring.