Sumps for water filter housings can, over time, become very difficult to remove due to pressure build-up. It is always recommended to keep the proper water filter housing removal wrench on hand in order to make filter changes as “stress free” as possible!
Also, it is best to change your O-rings with each filter change, as O-rings can degrade over time. When you encounter a leak from your water filter housing, the O-ring is most often your culprit. So it is best to keep several O-rings on hand for emergencies.