Stains. Corrosion. Instruments worn out before their time. These are problems every sterile processing department experiences and they can be among the greatest causes of stress, be costly to fix, and drag your department into the doldrums of dissatisfaction with your surgical customers.

How can you mitigate these issues? The water used in reprocessing can be a major cause. Your first course of action should be testing. Team up with your facilities department to have the water tested and compare the test results to the industry standard, AAMI TIR34:2014 “Water for the reprocessing of medical devices” (available at This gives you a path to providing more efficient service with better results. TIR34 provides a baseline for water quality that will help to address any water-based issues you may have. Continued evaluation of your water on a regular and especially seasonal basis is paramount. If your water supplies comply with AAMI TIR34, you will have fewer complaints and costly rescheduling of surgeries where instruments were rejected; save money on detergent because purer water requires less detergent to effectively clean instruments; and be less likely to deposit residues on the instruments, thus reducing corrosion and damage. If it does not comply, you need to bring it into spec.

TIR34 establishes maximum levels for water contaminants. Better water equals better results. How does your facility compare?

*mg/L = ppm

Maximum acceptable contaminant levels per AAMI TIR34:2014

TIR34 describes two kinds of water, utility water and critical water. Utility water is tap water and may be appropriate for certain parts of the cleaning process. Critical water is treated water (i.e., softened, RO, DI, or better) used to remove contaminants that may impede critical aspects of processing. In the final rinse, critical water provides better performance in removing residual detergent and impurities from the instruments than utility water.

Pure and impure water

Sterile processing departments have the goal of producing clean instruments in preparation for sterilization. Using impure water for this process will yield poor results and may corrode, stain, and decrease instrument lifespan. Further, greater amounts of impurities in the water require increased detergent dosage to compensate for those impurities.

This is true for sinks, ultrasonics, and washer-disinfectors. More detergent requires longer or repeated final rinses to remove residual detergent, increasing financial and time costs. Water can only dissolve so much stuff. If the final rinse water already has too much stuff in it, then it cannot dissolve residual detergent on the instruments, causes staining, or can end up in patients.

What is this stuff I am talking about? Dissolved contaminants. TIR34 discusses acceptable levels for these contaminants, but how do you know how much stuff there is in the water?

Testing should be done on a regular basis, as recommended in AAMI TIR34 and ST79. The contents of the water delivered to your facility changes seasonally and local conditions change unexpectedly; both can drastically affect cleaning performance and instrument condition in your department. Examples include everything from organic and inorganic fertilizer runoff in agrarian areas to a water main breaks, a fact of life in urban areas.

If you follow the recommendations in the standards, you are testing on a regular basis and have data to influence how you manage your process. How do you use this data to make better decisions?

Is my water acceptable for processing?

Your test results tell you if the values are within the ranges recommended by TIR34. If not, you need to implement water supply treatment, then confirm this with additional testing. You will likely have better visual appearance of the instrumentation, have fewer issues with the maintenance of the washers, and have fewer complaints from your customers.

Water treatment can be chemical or by filtration means. The table below shows the kinds of treatments that can be used to improve water purity.

Filtration and treatment for contamination in water supplies

Before you filter, you should test your water hardness. Softened water may solve many processing problems. It also makes filters work a lot more effectively.

Can water be too soft? Yes. Water that is too soft attacks copper pipes depositing copper ions on surfaces where they don’t belong. How do you know if the water is too soft before the effects are seen? By having a comprehensive and consistent testing program in place.

How often do I test?

Water testing should be done on a regular basis, at least quarterly. Your facilities engineering department may be doing this monthly or even weekly. Testing is economical compared to the cost of poor cleaning and having dirty instruments delay or cancel a surgery.

The final rinse

TIR34 and the IFU for cleaning for the majority of surgical instrumentation recommend critical water for the final rinse because it has superior ability to dissolve and remove residual contaminants from instruments.

Here are some global benchmarks for processing:

In Germany, 75% of all SPDs use RO water or better for all phases of washer-disinfector cycles; 95% use RO water or better for final rinse.