Tap Water Quality in Coimadai, VIC
Postcode 3340 · Supplied by Greater Western Water via Merrimu
Quality Score
About Coimadai
Coimadai is a suburb of 409 residents in Victoria (postcode 3340). The median age is 47. It falls within the Greater Western Water area. Neighbouring suburbs include Darley, Merrimu, Bacchus Marsh, Maddingley.
Most residents own outright (43%), while 41% own their home with a mortgage, while 11% rent. The median household income is $96,668 per year. The top countries of birth for residents are United Kingdom (21%), New Zealand (8%), and Philippines (8%).
Tap water in Coimadai is supplied by Greater Western Water. The suburb receives water via the Merrimu supply zone.
Water quality summary
Based on 2023-24 water quality reports, Coimadai achieves a WaterScore of 9.5 out of 10, rated excellent overall. Water hardness measures 62 mg/L, classified as moderately hard. This may cause light mineral deposits on fixtures over time. The pH level is 7.6, which is within the ADWG guideline range of 6.5–8.5. The water is fluoridated at 0.55 mg/L, well under the ADWG maximum of 1.5 mg/L. Chlorine, used for disinfection, measures 0.96 mg/L — well within the ADWG guideline of 5 mg/L. Some residents may notice a slight taste, which can be reduced by refrigerating water or using a carbon filter. Turbidity is 1.2 NTU, within the ADWG guideline of 5 NTU. E. coli was not detected in testing, meeting the ADWG standard for microbiological safety.
Compare with nearby suburbs: Darley , Merrimu , Bacchus Marsh
Census Data
Suburb snapshot
Population
Median Age
Median Income
Owner-occupied
Recommended filters for Coimadai
Products matched to your water profile
BRITA
Marella 2.4L Fridge Water Filter Jug (Maxtra+)
4.7 · 16,095 ratings on Amazon
Ideal for Coimadai — removes chlorine taste and odour.
ZeroWater
2.8L 5-Stage Jug (IAPMO Certified: PFOA/PFOS + Lead)
4.2 · 5,315 ratings on Amazon
A reliable 2.8l 5-stage jug (iapmo certified: pfoa/pfos + lead) suitable for Coimadai's water profile.
Purewell
8.5L Stainless Steel Gravity System
4.4 · 1,137 ratings on Amazon
Ideal for Coimadai — removes chlorine taste and odour.
Comparison
How Coimadai compares
Compared to Victoria and national averages
| Metric | Coimadai | VIC Avg | National Avg |
|---|---|---|---|
| Hardness | 62 mg/L | 28 mg/L | 85.3 mg/L |
| pH | 7.6 | 7.4 | 7.8 |
| Fluoride | 0.55 mg/L | 0.7 mg/L | 0.7 mg/L |
| Chlorine | 0.96 mg/L | — | — |
| Turbidity | 1.2 NTU | 1.8 NTU | 0.4 NTU |
| TDS | — | — | 275.7 mg/L |
Full Results
Detailed water quality data
All values compared against Australian Drinking Water Guidelines (ADWG)
| Parameter | Value | Unit | ADWG Guideline | Status |
|---|---|---|---|---|
| Alkalinity | 31 | mg/L CaCO3 | No limit | Measured |
| Aluminium | 0.05 | mg/L | < 0.2 | Good |
| Free Chlorine | 0.96 | mg/L | < 5 | Good |
| Total Chlorine | 1.17 | mg/L | < 5 | Good |
| Colour | 2 | HU | < 15 | Good |
| E. coli | 0 | MPN/100mL | < 0 | Compliant |
| Electrical Conductivity | 266 | No limit | Measured | |
| Fluoride | 0.55 | mg/L | < 1.5 | Good |
| Hardness | 62 | mg/L CaCO3 | < 200 | Good |
| Iron | 0.04 | mg/L | < 0.3 | Good |
| Manganese | 0.003 | mg/L | < 0.1 | Good |
| pH | 7.6 | pH units | 6.5 – 8.5 | Normal |
| Sodium | 21.2 | mg/L | < 180 | Good |
| Trihalomethanes | 0.061 | mg/L | < 0.25 | Good |
| Turbidity | 1.2 | NTU | < 5 | Good |
Safety
Safety assessment
Based on 15 parameters tested, all results fall within Australian Drinking Water Guidelines. E. coli was not detected, meeting the ADWG standard for microbiological safety.
Based on comparison with Australian Drinking Water Guidelines (ADWG)
Explained
What these numbers mean
Moderately hard (62 mg/L)
Water Hardness
Your water is moderately hard. You may notice light limescale deposits on kettle elements and taps over time. Soap lathers reasonably well, though slightly more product may be needed. Skin and hair are generally unaffected, and appliance lifespan should not be significantly reduced at this level.
Normal Range
pH Level
pH of 7.6 is within the ideal range of 6.5–8.5. The ADWG recommends pH between 6.5 and 8.5 for drinking water.
Fluoridated
Fluoride
Fluoride at 0.55 mg/L. Below the recommended range.
Chlorine
Disinfection
Chlorine measured at 0.96 mg/L, well within the ADWG guideline of 5 mg/L. Used for disinfection to keep water safe. May affect taste slightly — refrigerating water or using a carbon filter can help.
Learn more about these measurements in our water quality glossary — including Hardness , pH , Fluoride , and ADWG guidelines .
Advice
Practical tips for residents
Chlorine Levels Are Low
Chlorine in Coimadai measures 0.96 mg/L, which is low. Filling a jug and letting it stand for 30 minutes will reduce any residual taste.
Soft Water Advantage
Coimadai's water is moderately hard at 62 mg/L. You can use less soap and detergent, as it lathers easily with softer water.
Fluoride in Your Water
Fluoride measures 0.55 mg/L in Coimadai. Australian guidelines allow up to 1.5 mg/L. This is added by utilities to support dental health in the community.
Sediment Filtration
Turbidity is 1.2 NTU in Coimadai. A sediment pre-filter on your main line can help reduce fine particles and improve water clarity at the tap.
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FAQ
Frequently asked questions
Is tap water safe to drink in Coimadai?
How hard is the water in Coimadai?
What water utility supplies Coimadai?
Does Coimadai water have fluoride?
What is the water quality score for Coimadai?
What is the population of Coimadai?
Supplier
Water utility
- Utility
- Greater Western Water
- Supply Zone
- Merrimu
- Data Source
- Greater Western Water — GWW Annual Water Quality Report 2023 24
Nearby
Nearby suburbs
Same water utility, similar water quality
Similar Quality
Suburbs with similar water quality
Suburbs scoring between 8.5 and 10.0
Utility reports average the grid — not your home
Coimadai's water meets ADWG standards at the source, but old pipes, roof tanks, and ageing plumbing can add lead, copper or bacteria before the water reaches your tap. These won't show up in your utility report.
Check your own tap before buying a filter or assuming the suburb average matches your home.
Tetra
EasyStrips 6-in-1 Water Test (100 strips)
4.6 · 8,650 ratings on Amazon
Tests 6 parameters in 60 seconds: hardness, chlorine, pH, nitrate, nitrite, alkalinity. Cheapest way to verify your utility data.
Test my tap →Sponsored Amazon link. Check Amazon for current price and availability.
Heavy Metals
Drinking Water Test Kit (Lead, Copper, Iron, Mercury)
4.2 · 250 ratings on Amazon
20 tests. Detects lead, copper, iron, mercury — the things utility reports miss. Mobile-app results, EPA-standard thresholds.
Check metals kit →Sponsored Amazon link. Check Amazon for current price and availability.
Guides for Melbourne
In-depth articles on the water supply that serves Coimadai
Cite
Cite this page
Free to quote and reuse with a credit to WaterScore and a link to this page. Journalists and researchers can find key figures and contacts on our press and data page.
WaterScore. (2026). Tap water quality in Coimadai, VIC [Data set]. Compiled from Greater Western Water data (2023-24 annual report). https://waterscore.com.au/water-quality/coimadai-vic/
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Related
Explore more
Related pages for Coimadai, VIC
Is tap water safe?
Safety assessment
Water hardness
62 mg/L
Best water filter
Filter recommendations
Victoria water quality
State coverage
Greater Western Water
Water utility
Compare with Darley
Coimadai vs Darley
Compare with Merrimu
Coimadai vs Merrimu
Compare with Bacchus Marsh
Coimadai vs Bacchus Marsh
Disclaimer: The information on this page is for general informational purposes only and does not constitute medical advice, health recommendations, or professional guidance. Water quality data is sourced from Greater Western Water (2023-24 annual report) and reflects conditions at the time of utility testing — it may not reflect real-time water quality at your tap. Actual water quality can vary due to local plumbing, seasonal changes, and distance from the treatment plant. For specific health concerns, consult a qualified health professional. For the most current water quality information, contact your local water utility directly. See our Terms of Use.