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Certain contaminants in water supplies can cause severe complications in dialysis patients. If the water used for preparing dialysate and or reuse purposes, or the dialysate itself, exceeds the allowable limit for bacteria and endotoxins, the dialysis patient can exhibit clinical signs such as shaking chills, fever, hypotension, myalgias, nausea and vomiting (pyrogenic reactions), and possibility sepis. The onset of these symptoms usually occurs one to two hours after initiation of the treatment. Sophisticated water purification systems we provide to purify water; to a level determined to be safe for the patients. And the critical piece of equipment in these water purification systems is the reverse osmosis (RO) plant. The basic components of an RO system are the pre-filter, a pump, and membrane elements. The membrane elements are placed in stainless steel or FRP housings, which are then manifolded together.

The raw city water is fed through a back-washable sand filter followed by water softener. sand filter removes the suspended solids and softener removes calcium and magnesium ions. Softeners also remove small amounts of iron. After the softener, activated carbon filter is employed to remove chloramine, chlorine, and trace organics. It is important to keep the chloramine or chlorine in the system up to this point in order to minimize the chance of bacterial growth. 5 micron Cartridge filter is employed to remove particles greater than 5 microns to protect the RO membranes. Next comes the RO machine, which typically removes 90% to 95+ % of the dissolved salts. RO also removes bacteria and pyrogens as well as 99+ % of organic molecules over 200 daltons in molecular weight. In some cases where the raw water has a very high level of dissolved solids, a second RO machine in series or an ion exchange unit after the RO may be used to lower the dissolved solids level to an acceptable number.

The Association for the Advancement of Medical Instrumentation (AAMI) has set forth water standards as guidelines for dialysis centers to follow. These standards list maximum levels for ions found in water as well as for heavy metals and bacteria.

The goal of disinfection is to prevent and control the colonization of microorganisms, and a well designed water purification system and delivery loop is the first step in achieving this prevention. In order to prevent stagnation--a cause of bacterial grrowth--the distribution piping in direct-feed systems (those with no storage tanks) must have a velocity of at least 1.5 ft/sec, and in indirect feed systems (those with storage tanks present), at least 3 ft/sec. It should be a continuous fast flowing loop design with no dead ends, rough joints, or unused branches in the piping. The connections linking the product water to the dialysis machine should be accessible, minimal in length, and have a positive shutoff valve to prevent air from being drawn up into the loop. If a storage tank is present, it should be small in size in order to produce turbulent flows. It should also have a dish or conical shaped bottom for complete drainage, and have an airtight lid with a bacteria filter. The incorporation of an internal spray mechanism will also prevent water from stagnating on the exposed surfaces. Bacterial monitoring for the purpose of validating frequency and efficacy of disinfection is crucial and should be performed correctly and routinely. Strategies for controlling bacterial colonization include regular, simultaneous disinfection of the entire RO unit, the delivery loop, and the hemodialysis machines, as well as limiting "downtime" and ensuring that the system and distribution piping are well designed in the first place. Many different disinfectants exist and may be appropriate for RO systems. It is important to vary the disinfectants used in order to obtain different results such as biofilm removal and reduction of specific microorganisms.

AAMI and FDA standards state that 200 cfu/ml (colony forming units/ml) is the maximum bacterial concentration allowable in the product water used for dialysis purposes. The AAMI standard also expounds that the total microbial count in proportioned dialysate should not exceed 2,000 cfu/ml. Additionally, according to the standards, voluntary endotoxin (lipopolysaccharide) levels in the water used for reuse should not exceed 1 ng/ml or 5 EU (endotoxin units) as demonstrated by the Limulus amebocyte lysate (LAL) assay. AAMI recommends that bacterial monitoring should be performed once a moth on the RO product water and dialysate. More frequent bacterial monitoring should be performed if the system is opened for any reason, if a new piece of equipment has been incorporated, or if the results of the water or dialysate cultures exhibit higher than allowable counts.