INDUSTRIES · RAIN HARVESTING
of Australian rainwater tanks test positive for E. coli.
Conventional UV, chlorine and sand treatments leave the gap open. Purus closes it — 6-log pathogen removal at solar pressure, chemical-free, on the existing tank pad. ADWG-compliant water from the catchment infrastructure already on your property.
Two trends are colliding. Regional and rural town supply is under unprecedented pressure — Stanthorpe in southern QLD officially ran out of water in January 2020, and severe drought has gripped Victoria and South Australia since early 2024. At the same time, regulators are tightening what counts as "safe" potable supply for any commercial, community or food-handling context.
For roughly one in four Australian households — and a growing list of stations, regional councils, eco-resorts, schools, healthcare facilities, food businesses and indigenous community programs — the rainwater tank is no longer a backup. It's the primary supply. And the gap between what the tank can provide and what users actually need it to meet has never been wider.
of Australian rainwater tanks tested positive for E. coli — the standard indicator of faecal contamination. In a Southeast Queensland study, 63% of tank samples and 58% of household taps fed from those tanks exceeded the Australian Drinking Water Guidelines limit of <1 CFU E. coli per 100 mL.
2025 review of 25 years of Australian rainwater research · Applied and Environmental MicrobiologyThe contamination isn't surprising — it's faecal matter washed off the roof catchment by bird and possum droppings, leaves, and accumulated organic debris. The longer the dry period before the rain, the heavier the contamination load. Pathogenic E. coli strains (EPEC, ETEC, ExPEC virulence genes) have been detected in two-thirds of tanks studied, with documented links to gastroenteritis from untreated tank water.
For a private household using rainwater for the garden and laundry, this is a manageable risk. For anyone running a food premises, hospitality venue, school, healthcare facility, caravan park, community-based supply or commercial operation — it's a regulatory non-conformance and a liability waiting to happen. The Australian Drinking Water Guidelines require zero E. coli in 100 mL. Routine testing isn't a guideline for these contexts; it's an expectation.
Three approaches dominate Australian rainwater treatment. Each addresses part of the problem and concedes another. None of them give you ADWG-grade water at off-grid power without operator burden.
10 nm filtration physically excludes bacteria, protozoa and most viruses — not killed-and-hopefully-passed-through. Combined with optional RO polishing, the supply meets ADWG on every parameter, every cycle.
Operating pressure that small solar arrays sustain reliably. Pairs with off-grid power without inverter heroics or generator backup. A genuine off-grid potable solution, not an off-grid-pretending one.
A footprint that drops onto the existing tank slab — no new civil works, no shed, no permanent plant room. The catchment infrastructure already on the property becomes a compliant primary supply.
For each of these segments, the catchment asset is already on the property. The treatment train is the gap between what's there and what's needed.
RURAL & PASTORAL
Drought-cycle pressure on town supply is making rainwater the primary. ADWG-compliant water for staff accommodation, food preparation and stock-water that meets export-market drinking standards. Off-grid solar-pumped where mains power isn't viable.
COMMERCIAL · GREEN STAR
Green Star credits for rainwater harvesting and greywater recycling demand low-energy treatment that doesn't penalise the building's overall energy score. 1.8 bar operating pressure makes Purus the right architectural fit for both new commercial builds and sustainability retrofits.
HOSPITALITY · TOURISM
Off-grid hospitality already markets sustainability — but bottled water at scale undermines the story. Rainwater treated to potable standard on-site delivers the brand promise without the plastic. Compact footprint hides behind the back-of-house.
REGULATED · COMMERCIAL
Anywhere food is served, patients are treated, or children attend — routine testing against ADWG is required. A guaranteed ADWG-compliant supply removes a recurring compliance risk and the operating burden of repeated remedial treatment.
COMMUNITY · INDIGENOUS
Remote and very-remote communities where reticulated supply is impractical or unreliable. Containerised Purus 100.20 deployments on solar deliver community-scale potable from catchment infrastructure — drop-and-go, low operator burden, remote-monitored.
REGIONAL COUNCIL
Council assets serving small populations where mains extension is uneconomic. Purus replaces aging UV-and-chlorine plant with a single low-power treatment train — easier to maintain, more compliant, and built to ride out drought-cycle supply variability.
A rough guide based on indicative daily demand. Final sizing depends on tank capacity, roof area, peak draw profile, and whether RO polishing is needed for taste/TDS. Send us a brief and we'll size it properly within five business days.
| Use profile | Indicative daily demand | Suggested Purus | Power profile |
|---|---|---|---|
| Single station household / homestead | 0.5 – 2 kL/day | Purus 50.2 (small fixed) | Solar-compatible |
| Six-star commercial building / boutique resort | 5 – 30 kL/day | Purus 50.2 (small fixed) | Mains or solar-hybrid |
| School, healthcare facility, caravan park | 20 – 80 kL/day | Purus 50.2 (small fixed) | Mains or solar-hybrid |
| Mid-size hotel, conference, agri-process | 50 – 130 kL/day | Purus 100.5 (medium fixed) | Mains |
| Indigenous community supply, regional council asset | 80 – 200+ kL/day | Purus 100.20 (containerised mobile) | Solar / off-grid capable |
INDICATIVE ONLY · ACTUAL SIZING CONFIRMED DURING SCOPING
Send us a sample (we'll arrange the bottle) and we'll come back with a microbiological assessment, a sized Purus recommendation, and indicative CAPEX/OPEX. Most briefs turn around in five business days.
Sources & further reading