A micron rating describes particle size performance, not universal contaminant removal.
Evidence snapshot
- NHMRC (2025): The Australian Drinking Water Guidelines are a risk-management framework, not a single national pass/fail law. They separate health-based, aesthetic and operational considerations.
- NSF (2026): NSF standard numbers are not quality rankings. NSF/ANSI 42 covers stated aesthetic claims, 53 health-effect claims, 44 softeners, 55 UV and 58 point-of-use RO; the exact certified claim still has to be checked.
- US EPA (2005): The EPA distinguishes nominal from absolute micron ratings. A particle-size claim should not be extended to dissolved chemicals or microorganisms without the relevant product evidence.
These figures and standards are reference points, not a diagnosis of one home. Local water data, premises plumbing, flow and maintenance determine how they apply.
What the first observation can tell you
Start with the property itself. Follow the claim through four steps: target, mechanism, operating conditions and verification. A material test does not automatically prove the finished system; plumbing approval does not prove contaminant reduction; a micron number does not describe dissolved chemistry. The evidence should match the exact question the household is asking.
Where the claim stops
Nominal ratings usually indicate an approximate efficiency, while absolute ratings are tied to a defined retention threshold.
Official guidance describes population-level or supply-level risk; a component test describes stated test conditions; a household observation describes one property. None should silently stand in for another. Connect them only where the source, configuration and operating conditions genuinely match.
Measure flow and pressure under the same conditions
Smaller is not automatically better at whole-house flow because pressure drop and loading also matter.
Record static pressure and pressure at a known flowing outlet before and after treatment. A shower that feels weak is useful evidence, but it cannot separate a loaded cartridge from a partly closed valve or a wider supply change. Ask for the clean-system pressure drop and the design flow in litres per minute. Repeat the same check after service so the figures are comparable.
What to record before buying
Chemical reduction claims require evidence for the media and compound, not only a micron number.
Decide how the claim will be checked after installation. That may be a pressure reading, service-volume record, alarm status, hardness test or matched laboratory samples. Also write down who acts when the trigger is reached. A result without a maintenance response is not a complete treatment plan.
A practical household check
| Record | What to capture | Why it changes the decision |
|---|---|---|
| Claim | Write the exact target and unit | Prevents category errors |
| Conditions | Record flow, capacity and test basis | Tests relevance to the home |
| Verification | Choose a measure that matches the claim | Shows whether it worked |
Use the same notes when requesting more than one quote. Suppliers then have to answer the same water, flow and ownership brief rather than redefining the problem around their preferred product.
Where Water Analytics Australia fits
WAA's role is to turn the household brief into a proportionate design. That starts with source water, treatment goal, realistic peak flow, available pressure, installation access and the preferred service approach. Depending on the job, the answer may be whole-home staged treatment, point-of-use RO, the benchtop system or a combination. The written proposal should explain why each stage is present, the conditions behind each claim and what the customer will need to maintain.
Related WAA guides
- How to Read a Water Quality Report Without Being a Chemist
- Activated Carbon vs Catalytic Carbon: Which One Handles Chloramine?
- WAA Full Home Water Refining Systems
Common questions
Does one specification prove the whole product claim?
No. A micron rating, material test, plumbing approval or TDS reading answers a limited question. Check the exact finished model, target, test method, flow and capacity.
What is the most useful measurement?
Use the measurement that matches the decision. Follow the claim through four steps: target, mechanism, operating conditions and verification. A material test does not automatically prove the finished system; plumbing approval does not prove contaminant reduction; a micron number does not describe dissolved chemistry. The evidence should match the exact question the household is asking.
What should WAA receive before recommending a system?
Provide the postcode, water source, household size, bathroom count, busiest-use pattern, observed issue, desired result and any laboratory report with its units and sample point.
Sources and further reading
- NHMRC: Australian Drinking Water Guidelines, version 4.0
- NSF: Standards for water treatment systems
- US EPA: Water Health Series: Filtration Facts
The next useful step
Write down the source, the result you want, peak-use flow and the evidence already available. Then ask for a recommendation that gives every stage a defined job, states the operating assumptions and includes the service plan. That is enough detail to compare a WAA proposal with any alternative without relying on fear or brochure language.