**4. Additional and optional equipment**

**3.8. Plumbing**

228 Updates in Hemodialysis

Only qualified plumbers registered with the local water board and with prior experience in water systems are used to plumb new installations. The main components are the filters and the piping in between. Plumbing installations including those for haemodialysis must comply

This prevents treated water, containing disinfectants, from back flowing into municipal water supply. The device cannot be tested and so are changed routinely every two years according

The 2009 ISO guidelines recommend that piping should not contribute any chemicals eg copper, lead, zinc or chemicals. [9]. Common practice is the use of PVC (polyvinyl chloride) piping as it is non corrodible, is able to withstand high temperatures achieved during disin‐

Much controversy surrounds the potential leaching of plasticizer compounds from the dialysis tubing, including the dialyser membrane and their effects on health. Two compounds in particular, Bisphenol A and phthalate diesters are known to act as 'oestrogenic disrupting chemicals' which have been shown in rodent models, to cause liver, pancreatic, thyroid and developmental abnormalities [28, 29]. Their role in human disease remains unclear. Copper piping is used only for reject water and not for the piping that supplies the WRO and the dialysis machine, as copper can leach from the piping and result in copper toxicity to the patient [14]. Brass fittings may be minimally used for certain fixtures due to the risk of leaks and blowout with plastic couplings. Particular care needs to be taken to prevent use of and

There are two grades of wastewater created from the water filtration process. The first is reject water from the WRO, which has not come into contact with the patient and second, post dialysis effluent, which is produced during the actual dialysis process. Safe disposal of dialysis effluent water poses two issues. **Firstly**, because dialysis fluid is in contact with blood, it is a biological waste product and theoretically may contain bacterial or viral particles from the patient. There is however no evidence that this poses a definite infective risk. In one study dialysis wastewater was analysed and compared to municipal, industry, Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO) standards for wastewater use for agricultural applications. Apart from an expected higher conductivity, the dialysis wastewater did not exceed FAO standards for biochemical oxygen demand or bacteria [15]. **Secondly**, dialysis wastewater in the home setting is diverted to sewerage, which poses a practical dilemma for patients in the rural setting, where septic tanks are used. With the large volumes of dialysis wastewater created per treatment, this could quickly overflow

with the *Plumbing and drainage standard* of that country.

*3.8.1. Backflow device and stop valve*

to the manufacturer's specification.

*3.8.2. Piping, couplings, micro fittings and sealants*

fection and has a smooth inner surface to prevent biofilm.

contamination from adhesives, epoxy resins or bonding cements.

**3.9. Water disposal and saving – Green dialysis**

### **4.1. Cartridge filter with basic RO membrane**

These are small, under-counter-size WRO units. In remote areas where patients are supplied by borehole water, the feedwater can have high amounts of particulate matter, dissolved salts and metals (e.g. arsenic). A cheap pre-filtering system is required to return water to near drinking water standard to protect the more expensive downstream components of the filtration system. Water from rainwater and borehole supplied tanks requires a pump that provides pressures between 300 – 500Kpa as these filters operate on line pressure. The filter typically has a 3 stage system that involves a carbon prefilter cartridge leading into a RO cartridge. Typically the cartridges are changed every 6 months, although this is variable depending on the feedwater quality. When the reject rate of water starts to increase (i.e. less water per minute of treated water is produced), then the cartridges are changed sooner. Typically patients will notice that the storage tank takes longer to fill alerting them that an earlier change is necessary.

**Figure: 9: Holding tanks with booster pumps and back flow preventor**

A) Two 3000L holding tanks to provide an uninterrupted water supply in case of emergency. Note also the booster pumps in the centre. These ensure an inlet pressure of at least 550Kpa

(B) A backflow device.

**Figure 9.** Holding tanks with booster pumps and back flow preventor

#### **5. Water quality testing 4.2. Water temperature regulators**

outlined below. (*see Table 3*).

testing facility for all water analyses.

resulting dialysis water needs to meet minimum criteria for chemical and microbiological characteristics. These criteria form the basis of the definition for standard quality and ultrapure quality dialysis water. There are several available guidelines specifying the minimum allowable standards for water quality. (eg U.S. Association for the Advancement of Medical Instrumentation (AAMI) and the European best practice guidelines (EBPG). The ISO As blood is passed through a dialysis circuit, heat is radiated to the cooler ambient temperature and then is brought into contact with dialysis water. The temperature of this water may have significant seasonal or diurnal variation. Dialysis machines are capable of heating but not

(international organisation for standardisation) is an international collaboration of national standard bodies (ISO member bodies). Minimum water testing parameters from the ISO are summarised below. The ISO recommends at least annual testing for chemical contaminants and quarterly testing for microbiological contaminants (Table 2)(9). Ultimately a schedule of water testing must achieve two goals. Firstly, testing must ensure that a high quality of dialysis water is being delivered at the end of the filtration process. Perturbations in feed water quality and breakthrough in upstream filters do not usually result in fouling of the dialysis water, as there is a fair degree of redundancy built into each filter. Hence, even if, for example, a post-WRO sample reveals an elevated bacterial load, a well maintained further downstream ultrafilter should still prevent this exposure to the patient. Secondly, testing at different points in the circuit enables troubleshooting and localization of the problem area. As in the example above, the problem would be proximal to the WRO testing port and hence the carbon filters would be backwashed and the RO disinfected. A suggested schedule for water testing frequency in the home environment in

There are 4 main points of water testing. *(see table 3 and Figure 2).* Water samples are best sent to an experienced

The water purification system is a multiple layer system designed to progressively purify water at each step. The

cooling dialysis water to the required temperature. Feed water less than 10 degrees Celsius and greater than 30 degrees would require temperature adjustment. Feed water temperature also affects the integrity of the RO and particle filters, which have a maximum operating temperature set by the manufacturer, usually less than 35 degrees Celsius. In most units the temperature of dialysis water is typically 35ºC. A high dialysate temperature can result in haemolysis [19]. If feed water temperature is outside the recommended range then water temperature will need to be adjusted. This is usually not required in more temperate climates.

#### **4.3. Booster pumps**

typically has a 3 stage system that involves a carbon prefilter cartridge leading into a RO cartridge. Typically the cartridges are changed every 6 months, although this is variable depending on the feedwater quality. When the reject rate of water starts to increase (i.e. less water per minute of treated water is produced), then the cartridges are changed sooner. Typically patients will notice that the storage tank takes longer to fill alerting them that an

> A) Two 3000L holding tanks to provide an uninterrupted water supply in case of emergency. Note also the booster pumps in the centre. These ensure an inlet pressure of at least 550Kpa

> > (B) A backflow device.

The water purification system is a multiple layer system designed to progressively purify water at each step. The resulting dialysis water needs to meet minimum criteria for chemical and microbiological characteristics. These criteria form the basis of the definition for standard quality and ultrapure quality dialysis water. There are several available guidelines specifying the minimum allowable standards for water quality. (eg U.S. Association for the Advancement of Medical Instrumentation (AAMI) and the European best practice guidelines (EBPG). The ISO (international organisation for standardisation) is an international collaboration of national standard bodies (ISO member bodies). Minimum water testing parameters from the ISO are summarised below. The ISO recommends at least annual testing for chemical contaminants and quarterly testing for microbiological contaminants (Table 2)(9). Ultimately a schedule of water testing must achieve two goals. Firstly, testing must ensure that a high quality of dialysis water is being delivered at the end of the filtration process. Perturbations in feed water quality and breakthrough in upstream filters do not usually result in fouling of the dialysis water, as there is a fair degree of redundancy built into each filter. Hence, even if, for example, a post-WRO sample reveals an elevated bacterial load, a well maintained further downstream ultrafilter should still prevent this exposure to the patient. Secondly, testing at different points in the circuit enables troubleshooting and localization of the problem area. As in the example above, the problem would be proximal to the WRO testing port and hence the carbon filters would be backwashed and the RO disinfected. A suggested schedule for water testing frequency in the home environment in

As blood is passed through a dialysis circuit, heat is radiated to the cooler ambient temperature and then is brought into contact with dialysis water. The temperature of this water may have significant seasonal or diurnal variation. Dialysis machines are capable of heating but not

There are 4 main points of water testing. *(see table 3 and Figure 2).* Water samples are best sent to an experienced

**Figure: 9: Holding tanks with booster pumps and back flow preventor**

earlier change is necessary.

230 Updates in Hemodialysis

**5. Water quality testing** 

**4.2. Water temperature regulators**

**Figure 9.** Holding tanks with booster pumps and back flow preventor

outlined below. (*see Table 3*).

testing facility for all water analyses.

When feedwater originates from rainwater or borehole, it is stored in a tank. A booster pump is necessary to pump water to the filtration system (Figure 11). Some homes especially older ones may have low mains water pressure. This may be due to low supply pressure from the municipality, corrosion or faulty pressure restrictors. If not correctable then such homes may also require a booster pump. This must be sufficient to meet the minimum pressure require‐ ments of the RO filter, which is typically between 1 to 8 bars.

#### **4.4. Iron removal units**

In some circumstances high iron content in the feedwater may necessitate an independent iron removal system. A dedicated iron filter (e.g. BIRM® Clack Corporation, Wisconsin 53598-0500 USA) is available. The ISO does not specify a level for iron in dialysis water but does recognise that it may foul downstream filters [9].
