No, I'm not talking about the one-hit wonder song "Amy" by Pure Prairie League...I'm talking about AAMI (the Association for the Advancement of Medical Instrumentation), the organization which regulates water quality within dialysis units.
The municipal water supply derives from both ground water (e.g., below the surface, like wells) and surface water (e.g., lakes and rivers) sources. A variety of processing steps are typically undertaken--such as the addition of deflocculants such as aluminum, decontaminants such as chlorine compounds, filtering out of particulate matter, and addition of fluoride for the prevention of tooth decay (props to the Precious Bodily Fluids Nephrology blog)--in order to make the water acceptable for drinking. It is not, however, acceptable for dialysis. Compared to the 2 Liters of fluid a human typically drinks in a day, the dialysis patient is exposed to between 100-200 Liters of dialysate water, and any impurities which might be present, per dialysis session. Thus it is essential to regulate and monitor the amount of bacteria and other chemicals with the dialysis water supply. AAMI is the group which provides oversight of such regulations. A comprehensive review of current AAMI standards can be found here.
An example of what happens when these standards are not adhered to occurred during a 1987 incident in a Philadelphia-area outpatient dialysis unit in which high levels of chloramine resulted in an outbreak of hemolytic anemia amongst dialysis patients. Fortunately, no patients died.