PSR has been formulated to rid your potable fresh water system of odors and discoloration by attacking the source. Scale builds on low lying, flat sections of your system, allowing bacteria to form. PSR targets these areas and brings new life to your system. Use PSR to remove hard water stains, lime scale, rust, or any other mineral based scales deposits. Scale builds on low lying, flat sections of your system, allowing bacteria to form. PSR targets these areas and brings new life to your system. Use PSR to remove hard water stains, lime scale, rust, or any other mineral based scales deposits. If you have ever seen what contaminated fresh water looks like than you can appreciate what PSR can do. Originally designed to cure problems within municipal drinking water system, PSR has been specially formulated to meet strict NSF requirements. All of our descalers are built on our proven formula which provides a safe, non-toxic and biodegradable solution. PSR takes it one step further by only using food grade rated materials. This gives you piece of mind knowing that your system will remain safe for drinking.