Water Use in Dialysis
During an average week of hemodialysis, a patient can be exposed to 300-600 liters of water, providing multiple opportunities for potential patient exposure to waterborne pathogens. Adverse patient outcomes including outbreaks associated with water exposure in dialysis settings have resulted from patient exposure to water via a variety of pathways; including improper formulation of dialysate with water containing high levels of chemical or biological contaminants, contamination of injectable medications with tap water, and reprocessing of dialyzers with contaminated water. For the health and safety of hemodialysis patients, it is vital to ensure the water used to perform dialysis is safe and clean.
The Association for the Advancement of Medical Instrumentation (AAMI)external icon in conjunction with the International Standards Organization (ISO) have established chemical and microbiological standards for the water used to prepare dialysate, substitution fluid, or to reprocess hemodialyzers for renal replacement therapy. The AAMI standards address:
- Equipment and processes used to purify water for the preparation of concentrates and dialysate and the reprocessing of dialyzers for multiple use.
- The devices used to store and distribute this water.
- The allowable and action threshold levels of water contaminants, bacterial cell counts, and endotoxins. Refer to specific reference listed for full details on maximum allowable chemical contaminates and bacterial/endotoxin limits.
Table. AAMI Water Standards
|Reference Document||Allowable water Total Viable Count (TVC)||Action level water Total Viable Count (TVC)||Allowable Level water Endotoxin Unit (EU)||Action Level water Endotoxin Unit (EU)|
(Minimum regulatory requirement)
For the rationale for water treatment in hemodialysis: “Water Systems in Health-Care Facilities” in the Guidelines for Environmental Infection Control in Health-Care Facilities.
The Guidelines for Environmental Infection Control in Health-Care Facilities (MMWR June 6, 2003) pdf icon[PDF – 48 pages] provides recommendations on dialysis water quality and dialysate on pages 19 &20.
VIII. Dialysis Water Quality and Dialysate
|A||Adhere to current AAMI standards for quality assurance performance of devices and equipment used to treat, store, and distribute water in hemodialysis centers (both acute and maintenance [chronic] settings) and for the preparation of concentrates and dialysate.||IA, IC|
|B||No recommendation is offered regarding whether more stringent requirements for water quality should be imposed in hemofiltration and hemodiafiltration||No recommendation|
|C||Conduct microbiological testing specific to water in dialysis settings.||IA, IC|
|C1||Perform bacteriologic assays of water and dialysis fluids at least once a month and during outbreaks using standard quantitative methods.
|C2||In conjunction with microbiological testing, perform endotoxin testing on product water used to reprocess dialyzers for multiple use.||IA, IC|
|C3||Ensure that water does not exceed the limits for microbial counts and endotoxin concentrations outlined in Table 18.||IA|
|D||Disinfect water distribution systems in dialysis settings on a regular schedule. Monthly disinfection is recommended.||IA, IC|
|E||Whenever practical, design and engineer water systems in dialysis settings to avoid incorporating joints, dead-end pipes, and unused branches and taps that can harbor bacteria.||IA, IC|
|F||When storage tanks are used in dialysis systems, they should be routinely drained, disinfected with an EPA-registered product, and fitted with an ultrafilter or pyrogenic filter (membrane filter with a pore size sufficient to remove small particles and molecules >1 kilodalton) installed in the water line distal to the storage tank.||IC|
(The AAMI guidelines listed in this document are from 1993, refer to the current AAMI standards for the most up to date information.)
|Category IA||Strongly recommended for implementation and strongly supported by well-designed experimental, clinical, or epidemiologic studies.|
|Category IB||Strongly recommended for implementation and supported by some experimental, clinical, or epidemiologic studies, and by a strong theoretical rationale.|
|Category IC||Required by state or federal regulations. Because of state differences, readers should not assume that the absence of an IC recommendation implies the absence of state regulations.|
|Category II||Suggested for implementation and supported by suggestive clinical or epidemiologic studies or by a theoretical rationale.|
|No recommendation||Unresolved issue. These include practices for which insufficient evidence, or no consensus exists regarding efficacy.|
What is a boil water advisory(BWA)?
A BWA is issued to protect the community from waterborne infectious agents. A BWA is issued only after careful consideration among representatives from public health, regulatory agencies, and municipal departments after positive tests (e.g., positive samples for fecal coliforms, changes in turbidity measurements) or line breaks.
Can we dialyze patients during a boil water advisory (BWA)?
Yes, if the water treatment components in use are sufficient to remove or destroy bacteria, Reverse Osmosis (RO) will protect the product water from having microbial contamination. Deionization (DI) unit does not remove or destroy bacteria, so if DI is being used as the main water treatment (rather than RO), you will need a submicron or endotoxin/ultrafilter downstream of the DI unit. If an ultraviolet (UV) irradiator is used, the filter should be located after the UV irradiator. Close monitoring of the resistivity of the product water will be needed to detect any decrease in quality. Also consider weekly microbial assessment of the product water during the BWA.
Keep in close contact with the municipal water supplier because they may choose to “shock” treat (hyperchlorinate) their distribution system to bring it back into compliance with the acceptable standards for drinking water. If the city “shocks” their water system, you may see chlorine/chloramine break through. Review your testing procedures with staff and alert them to be vigilant for potential break through so that patients will be protected from exposure to chlorine/chloramine.