MMIC Medical Systems


The adage “garbage in, garbage out” is an accurate assessment for steam sterilization.  If you need to chemically treat your feedwater and using steam filters to produce clean, dry steam it nevertheless may not be sufficient to meet the needs of Sterile Processing Services.


For instance, many healthcare facilities soften their municipal water supply, unknowingly feeding treated water that’s still too hard for producing high quality steam for sterile reprocessing.[1]  Water softened to 4-16 mg/L hardness will still accumulate chalky spotting and deposit formations over time.  This results in more frequent sterilizer chamber cleanings and shorter lifespans of medical instruments.


But even with ultra-low water hardness, feedwater that’s high in Total Dissolved Solids (> 150 mg/L) and chlorides[2] can still cause problems for instrument reprocessing.  Staining, spotting, corrosion, wet packs, and incidents of bioburden are common challenges in Sterile Processing and are due to the quality of the sterilizing steam, which depends on the quality of the steam boiler’s feedwater.


There’s a long history in healthcare for the chemical treating of boiler feedwater, incorporating steam filters, and scheduling of boiler blowdowns to maintain the boiler equipment and produce clean, dry steam.  However, if the incoming water quality is deficient, facilities will be faced with steam filters quickly building up contaminates and potentially clogging within days, increasing more frequent but less effective boiler blowdowns, and ultimately still chasing defects and dealing with frequent reprocessing rework in their medical device reprocessing.


There’s an alternative approach to creating clean dry steam for sterile reprocessing that often gets overlooked: clean steam.


Clean steam is steam generated from purified water, most commonly from reverse osmosis filtration or deionization treatment.  Instead of requiring multiple chemical treatments such as anti-scaling, pH control agents, neutralizing amine, or alkalinity builders, purified water has significantly reduced contaminate levels, simplifying water conditioning.  Corrosive dissolved salts are removed from the steam feedwater.  Fewer boiler blowdowns and sterilizer chamber cleanings are required.  Staining and spotting agents are eliminated.  No residues are deposited by the steam onto medical instruments, eliminating potential sites for future microbiological growth once the instrument surfaces have cooled down.  Dry steam ensures there’s no wet packs at the end of the sterilization cycle.  Microbial and pyrogen-free feedwater results in microbial and pyrogen-free steam.  Quality in, quality out.


Today’s modern high rated boilers are more sensitive to the quality of the steam feedwater.  More steam sterilizers on the market now operate off purified feedwater or clean steam.  And with sterile reprocessing steam accounting for less than 5% of the total steam production for the average medical center facility usage, facilities are re-examining the historical assumptions on how to produce clean, dry steam for sterile reprocessing.

[1] Steam feedwater hardness < 1 mg/L, Table 1, “Categories and recommended levels of water quality for medical device

reprocessing,” AAMI TIR34: 2014/ (R)2017, Water for the reprocessing of medical devices.


[2] Steam feedwater chloride < 1 mg/L, Ibid