Can’t Open the Filter Housings on Your Undersink Water Filter or Reverse Osmosis Unit?

1. The first thing of all is relieve the pressure on the housings.  With a filter, turn off the inlet water and open the faucet.  Leave it locked open while you work.  If you have a reverse osmosis unit, also turn off the valve on the storage tank. When no water is coming from the faucet, you should be able to open the housing.

2. To open, turn the housing counterclockwise.  Think of it this way: If you put the filter wrench on the extreme right housing and point the handle away from the housing to the left, you would use your right hand and pull back toward your body to open the housing.

3. Get into a comfortable position. If the unit is installed in an awkward, hard-to-reach location, you may have to pull it out to a place where you can address it comfortably. In the worst case, you may have to uninstall it so you can lay it on its back to get more leverage.  (Remember that the housings are full of water, so it’s going to run on the floor when it opens if it’s lying sideways.)

4.If all else fails, you can get more leverage by lengthening the wrench handle with a pipe or a vacuum cleaner wand.  Or you can even buy a special wrench designed for very tough jobs.  See WR012 on this page.

5. Extreme methods: Someone suggests using a hair dryer to warm the filter cap causing it to expand and thus loosen more easily.  Another suggestion, and I’ve seen this work with larger housings, is to apply the wrench to the housing and tap on the wrench handle with a small hammer or rubber mallet. The shock from the mallet tapping can break the housing loose and let you open it.

6. Finally, this may sound strange, but it is important.  When you apply steady pressure to the wrench to loosen the housing, believe that it will open.  In fact, think about what it will feel like when it breaks loose and opens.