UV Sterilisation & Pathogen Removal

Bacteria and viruses in drinking water are the most serious water problem to solve — pathogens cause acute illness in days, where chemicals usually cause harm only over years of exposure. Australian mains water is disinfected at the treatment plant, so most homes do not need pathogen-stage filtration. Tank water, bore water, dam supplies, and rural catchments are different — they need active disinfection before use.

The two practical methods:

• UV sterilisation — water passes a UV-C lamp inside a quartz sleeve. UV disrupts microbial DNA, preventing reproduction. No chemicals added, nothing to taste, runs continuously while water is flowing. Standard rural and bore-water solution.
• Ultrafiltration cartridges (UF) — physical barrier with pores small enough to block bacteria and protozoa (typically 0.02 micron). Works without electricity. Will not catch viruses (which are smaller than the pores).

NSW Health and the Australian Drinking Water Guidelines recommend a multi-barrier approach for any non-mains supply used for drinking — sediment, carbon, and UV is the standard configuration.

How to choose

• Rainwater tank, drink the water? UV is the standard and safest choice. Pair with sediment + carbon upstream — UV needs clear water to work, and the carbon stage handles taste.
• Bore water with bacterial contamination? Same UV setup, plus consider iron and hardness pre-treatment depending on the water test results.
• Want pathogen protection without electricity (off-grid, caravan)? Ultrafiltration cartridges are the option. Slower flow than UV and will not catch viruses, but no power needed.

UV sizing matters: the steriliser must process all water at peak flow, with enough contact time to deliver the rated dose. A UV unit rated 30 L/min on a system that peaks at 40 L/min will under-dose during peak demand. Every product page lists the rated flow rate. Match it to your peak demand, not your average.

Lamp replacement is annual on most systems. Skipping or stretching the interval defeats the purpose — UV lamps continue producing visible light long after the UV-C output has degraded below the disinfection threshold, so a "still glowing" lamp is not a safety indicator.