Bacteria and Microorganisms

UV disinfection is highly effective against most microorganisms found in Australian household water sources. Its effectiveness in removing or inactivating bacteria, including E. coli and coliforms, is essentially complete at the correct UV dose, typically 40 mg/cm² or higher. For protozoan parasites, including Giardia and Cryptosporidium, UV is particularly valuable because these organisms are resistant to chlorine at practical doses but are highly susceptible to UV light inactivation even at modest doses.

For viruses, UV treatment is effective against most enteric viruses at standard residential doses, though some adenoviruses require a higher UV dose for complete inactivation. In the context of Australian tank and bore water use, where viral risk is generally lower than bacterial and protozoan risk, a standard residential UV system provides adequate protection for most households.

The critical caveat is that UV treatment only works in clear water. Any turbidity, iron, colour, or particles in the water that absorb or block the ultraviolet light pathway will reduce the effectiveness of removing pathogens. This is why our water filter systems for tank and bore water always include proper pre filtration stages upstream of the UV unit. Our Armour Water team sizes every UV water system to your specific water conditions and flow requirements.

If you are using rainwater tank water for drinking water or food preparation, UV treatment is strongly recommended. Australian rainwater tanks are exposed to a range of contamination pathways, including bird and animal droppings on roof catchments, leaf and organic debris, and, in some cases, insect and rodent access to the tank itself. All these pathways can introduce bacterial contamination, including E. coli and coliforms, which make unfiltered tank water unsafe for consumption.

The Australian Drinking Water Guidelines acknowledge that properly maintained and treated rainwater can be a safe drinking water source, but the key word is ‘treated’. A tank water filtration system that includes sediment filtration, carbon treatment for tastes and odours, and UV disinfection as the final stage delivers water that meets the microbiological safety standards of a well managed municipal supply.

For households using tank water only for non potable purposes such as garden irrigation and toilet flushing, the microbiological risk is lower, and the treatment requirements are less stringent. However, for any household where tank water reaches a tap used for drinking or cooking, a complete water treatment system, including UV disinfection, is the responsible choice. Light disinfection with UV is chemical free, low maintenance, and very affordable relative to the health protection it provides.

A standard carbon block or sediment water filter does not reliably remove bacteria from bore water. Standard carbon and sediment filter systems are designed to address chemical contaminants, chlorine, taste and odour issues, and physical particles. They are not rated for bacteria removal and should not be relied on for microbiological safety in bore or tank water applications.

What water filters remove effectively are the physical and chemical contaminants that affect water quality, including clarity, taste, and odour. For bacteria, the right technology is either UV disinfection, reverse osmosis (which physically blocks bacteria through the membrane), or, in some specialised applications, absolute rated hollow fibre membrane filters rated at 0.1 microns.

The standard approach our team recommends for bore water microbiological safety is a multi stage water filtration system that combines sediment pre filtration, iron and carbon treatment, and a UV water disinfection unit as the final stage. This combination addresses physical, chemical, and microbiological water quality in one integrated water treatment system that is practical, maintainable, and genuinely effective.

Both UV treatment and chlorine disinfection are effective methods for killing or inactivating pathogens in water supplies, but they work through entirely different mechanisms and have different practical implications for household use.

Chlorine is a chemical disinfectant that kills pathogens through a chemical reaction. It is widely used in municipal water treatment because it maintains a residual protective effect as water travels through distribution pipes, helping prevent recontamination throughout the network. The downside is that chlorine significantly affects the taste and odour of drinking water, reacts with naturally occurring organic matter to form potentially concerning disinfection byproducts (DBPs), and can irritate sensitive skin in shower water.

UV disinfection uses UV light to physically damage pathogen DNA, preventing reproduction without adding any chemicals to the water. It leaves no residual in the treated water supplies, produces no disinfection byproducts, does not affect taste or odour, and is effective against Cryptosporidium and Giardia that are resistant to chlorine. The limitation is that UV treatment provides no ongoing residual protection after the treatment point, which is why it is not suitable for long distance distribution networks but is ideal for point of use or point of entry water filter systems in residential properties.

A UV water treatment system requires minimal but important regular maintenance to remain effective. The primary maintenance task is the annual replacement of UV lamps. Although the lamp may continue to glow after its rated service life of approximately 9,000 hours (roughly one year of continuous operation), the germicidal UV output declines significantly over time. A lamp that appears to be working may no longer be delivering the required UV disinfection dose to effectively inactivate pathogens.

The quartz sleeve surrounding the UV lamp also requires periodic cleaning or replacement. Mineral scale and biofilm can build up on the sleeve, reducing the transmission of UV light into the water and lowering treatment effectiveness in removing pathogens. The sleeve should be inspected and cleaned every six months and replaced when clouding or etching cannot be removed.

Pre filtration stages upstream of the UV systems also require regular cartridge replacement, because a clogged pre filter that allows turbid water to reach the UV chamber will significantly reduce microbiological protection. Armour Water provides comprehensive maintenance programs for all the water filter systems we install, including UV lamp supply, sleeve replacement, and pre filter cartridge service. Our team tracks your system's service schedule and contacts you when maintenance is due, so your water treatment protection is never compromised.