I have a Watts Premier Reverse Osmosis water purifier installed. I am trying to do the annual maintenance and change all of the filters. I cannot get any of the filter housings to unscrew. I'm using the tool that came with it but they will not budge.

I suspect that the filter bowls are seized by sediment or may have got too tight, and/or the wrench is too short to get any leverage to turn the filer bowls off.

https://www.wattspremier.com/manuals/199349.pdf

The wrench tool looks a bit cheesy.

You may need a strap pipe wrench from a hardware store, see several pictures here:

strap pipe wrench - Google Search

They also use these types of tools to remove oil filters on vehicles, and can be found at auto parts stores.

With this handle you can use a short piece of pipe as a handle extension to give more leverage.

Once the filter bowls are off, use the same water soluble lubricant used on the O rings to lubricate the threads of the filter bowl.

Thank you, I bought a strap wrench at Lowe's and am going to try that. I will post after I am finished--and make sure to lubricate the threads also.
Thanks!!