Derby
North West Region · Western Australia · Reporting period 2023-2024
The verdict
Derby's water is much softer and purer than most other localities in the North West Region.
At a glance
Position within the North West Region
Purity
By-products & nitrate
Purer than 77% of North West Region supplies
Clarity
Turbidity, colour, metals
About average for the North West Region
Taste
Sodium, chloride, TDS
About average for the North West Region
Hardness
Calcium & magnesium
Softer than 88% of North West Region supplies
pH balance
How close to neutral (7.0)
More neutral than 71% of North West Region supplies
Full readings
Typical (mean) value at Derby versus the North West Region average.
Purity & health
| Parameter | Derby | Region avg | Unit |
|---|---|---|---|
| Trihalomethanes (THMs) | 0.00 | 0.02 | mg/L |
Clarity & appearance
| Parameter | Derby | Region avg | Unit |
|---|---|---|---|
| Iron | 0.01 | 0.01 | mg/L |
Taste & saltiness
| Parameter | Derby | Region avg | Unit |
|---|---|---|---|
| Sodium | 117 | 66.3 | mg/L |
| Chloride | 90.0 | 88.9 | mg/L |
| Total Dissolved Solids (TDS) | 433 | 511 | mg/L |
| Sulphate | 5.0 | 29.6 | mg/L |
Hardness & scale
| Parameter | Derby | Region avg | Unit |
|---|---|---|---|
| Hardness | 14.0 | 171 | mg/L |
| Alkalinity | 157 | 179 | mg/L |
| Silica | 15.0 | 42.6 | mg/L |
pH balance
| Parameter | Derby | Region avg | Unit |
|---|---|---|---|
| pH | 7.8 | 7.8 | pH units |
Compare nearby
All of North West Region →Data & methodology
Data source: Water Corporation of WA Drinking Water Quality Annual Report 2023-2024.
Regional ranking: Each measured parameter is ranked against every other locality in the North West Region using the typical (mean) reading. Lower readings rank better, except pH where the score is distance from neutral (7).
ADWG safety check: Every reading is independently checked against the NHMRC Australian Drinking Water Guidelines; any value above the limit is flagged regardless of how it compares to neighbours.