Guidelines for Chlorination of Dialysis Water Systems
After water disruptions or emergencies, change the pretreatment filter and disinfect the dialysis water system with an EPA-registered product to prevent colonization of the reverse osmosis membrane and downstream microbial contamination. 1
Context: When Chlorination is Indicated
The CDC/HICPAC guidelines specifically address chlorination in the context of remediation after water system disruptions or emergencies, not routine maintenance. This is a critical distinction that dialysis units must understand.
Emergency Situations Requiring Action
Chlorination protocols apply when:
- Significant water disruptions occur with heavy microbial or chemical contamination
- Municipal boil water advisories are issued
- Cross-connections with sewer lines happen
- Sewage intrusion or flooding affects the facility
- Service disruptions compromise water quality
Specific Chlorination Protocol for General Water Systems
When corrective decontamination is necessary 1:
Chlorination Parameters:
- Add sufficient chlorine (preferably overnight) to achieve free chlorine residual of >2 mg/L (>2 ppm) throughout the system
- Flush each outlet until chlorine odor is detected
- Maintain elevated chlorine concentration for >2 hours but <24 hours
- Perform decontamination when fewest occupants are present (nights/weekends)
Critical Exception for Dialysis Systems
For dialysis water systems specifically, the guideline diverges from general water system chlorination: Rather than using the standard chlorination protocol above, you must change the pretreatment filter and disinfect with an EPA-registered product designed for dialysis systems 1. This protects the reverse osmosis membrane from damage and prevents downstream contamination.
Important Caveat: Chlorine-Resistant Organisms
Use thorough flushing instead of chlorination if highly chlorine-resistant microorganisms (e.g., Cryptosporidium spp.) are suspected as water contaminants. 1 This is particularly relevant given dialysis patients' immunocompromised status.
Post-Remediation Steps for Dialysis Units
After water quality is restored:
- Change pretreatment filters
- Disinfect with EPA-registered dialysis-specific products
- Run water softeners through regeneration cycle
- Flush and restart equipment per manufacturer instructions
- Resume routine microbiological monitoring
Common Pitfall to Avoid
Do not apply standard building water system chlorination protocols directly to dialysis reverse osmosis systems. The RO membranes can be damaged by chlorine exposure, and residual chlorine poses severe hemolysis risk to dialysis patients. The guideline explicitly calls for EPA-registered products specifically designed for dialysis water systems rather than standard chlorination 1.
Routine Water Quality Standards
While the provided guidelines focus on emergency chlorination, research evidence indicates that optimal dialysis water treatment should include double reverse osmosis with regular disinfection using appropriate methods 2. The goal is achieving "ultra-pure" dialysate (microbial count <0.1 CFU/mL, endotoxins <0.03 U/mL) through proper system design and maintenance rather than relying on emergency chlorination 2, 3.