water for hospitals, clinics and labs: ultra-pure electro-deionised AS4187 water and sterilised water

ultra pure water for hospitals and labs to comply with AS4187

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In hospitals, dental clinics and other facilities used by vulnerable populations, prevention, monitoring and testing protocols for pathogens in the water distribution system should be maintained in such a way that colonisation is prevented or minimised.

1. Water needs in hospitals, clinics and labs

Watercore engineers collaborate with labs, clinics and hospitals to provide the best solutions and treatment for ultra pure water for their business compliant with AS4187 and/or ISO3696.

In general labs, clinics and hospitals require ultra pure water for different purposes:

Cleaning and disinfecting RMDs (Reusable Medical Devices) in washer disinfectors and steam sterilizers
Analytical laboratory use

The treatment process to obtain ultra pure water combines several stages where membranes play a very important role. Water is filtered through activated carbon and softened with resins in order to limit the danger of scaling and fouling through the double-pass reverse osmosis.

EDI can be used as a post-treatment for deionization when a higher purity is required (typically 10 MegOhm*cm).

2. Bacteria growth in water: what makes bacteria proliferate and grow

A number of common water contaminants, also known as substrate, are likely to be used by bacteria for growth:

Organic compounds based on Carbon (C), Hydrogen (H), Oxygen (O) and Nitrogen (N)
Minor elements such as compounds of Phosphorus (P), Potassium (K), Sulphur (S) and Magnesium (Mg)
Trace of metal ions such as Iron (Fe), Nickel (Ni) and Cobalt (Co).

Prevention of bacterial proliferation is easier when the presence of all these elements is minimal but, in general, the main pollution that always needs to be eliminated for a minimum water disinfection is the first one : organic compounds.

Ingress of contaminants can occur through tanks, pipes and connections to the pipe network and monitoring the integrity of the distribution system is a fundamental to guarantee the quality of water supplied to patients and health personnel.

3. Water disinfection: for hospitals, clinics and labs: choosing the right disinfection method

Different factors must be assessed before deciding the most appropriate disinfection method for a water supply. A satisfactory disinfection requires a disinfectant concentration (dosing) combined with a contact time. Disinfection by-products are another important concern as some of them can be dangerous for human health.

Disinfecting Agent	Chlorine	Chloramines	Ozone	UV
Bacteria Inactivation	++	+	+++	++
Virus Inactivation	+++	+	+++	++
Protozoa Cyst Inactivation	0	0	+	+++
Minimum Contact Time	30 min	2 hours	2 minute	1 second
By-products	THMs and chlorinated acetic acids	Halonitrils	Bromates (BrO3-) dangerous @ 10ug/L. Manganese Oxide (MnO2)	0
Residual Effect	+	++	0	0

Silver:

According to the Australian Drinking Water Guidelines “Silver is a weak biocide/bacteriostat that has been used occasionally for disinfection, particularly in point-of-use devices. However, there is no reliable evidence that these products worked effectively to kill micro-organisms. A long exposure time of several hours to days is required for any biocidal effect to be observed” . For this reason we recommend alternative disinfection methods.

4. internal water distributions in hospitals, clinics and labs: corrosion and biofilm growth and repairs

Some procedures should be put in place and maintained to prevent the contamination of the internal water distribution system:

Maintenance and repairs must be performed in a way that will prevent contamination.
Corrosion in pipes must be prevented as it results in leaching of metals with a potencial effect on health.
Scaling in pipes must be prevented as it represents a base for bacterial growth.
Biofilms must be minimised.

5. Main water quality parameters for rmd's in accordance with AS4187

	Final Rinse Water –Washer Disinfectors	Steam Generator Feedwater Quality	Steam Sterilizers Feedwater Quality
Appearence	Colourless clean without sediment	Colourless clean without sediment	Colourless clean without sediment
PH	5.5 – 8	5 – 7.5	5 – 7
Conductivity @ 25C	30 μS/cm	5 μS/cm	3 μS/cm
Total Dissolved Solids (TDS)	40 mg/l	10 mg/l	——
Total Hardness	50 mg/l (CaCO3)	0.02 mmol/l	0.02 mmol/l
Chloride (Cl)	10 mg/l	2 mg/l	0.1 mg/l
Lead (Pb)	10 mg/l	0.05 mg/l	0.05 mg/l
Iron (Fe)	2 mg/l	0.2 mg/l	0.1 mg/l
Phosphate (P2O5)	0.2 mg/l	0.5 mg/l	0.1 mg/l
Silicate (SiO2)	0.2 mg/l	1 mg/l	0.1 mg/l
Cadmium (Cd)	—–	0.005 mg/l	0.005 mg/l
Total count (cfu/100 ml)	10	—–	—–
Endotoxin (EU/ml)	0.25	—–	—–

6. ultra pure water for hospital and labs

What is the difference between Electrodeionization (EDI) and conventional Deionization

Deionization, also referred to as demineralization or ion exchange, is the process of removing ions from water with the use of synthetic resins.

In contrast to conventional ion exchange in which resins are exhausted and must be chemically regenerated, EDI utilizes an electric current for continual resin regeneration.

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