⚡ Water Electrical Conductivity
In short
Conductometric determination of electrical conductivity of water and wastewater. The test is performed according to PN-EN 27888:1999; Measurement range: 1 μS/cm – 2000 mS/cm (depending on probe). The procedure comprises 9 steps (about 9–11 min in total); it is used for: Drinking water quality control (limit ≤2500 μS/cm at 20°C), Surface and groundwater monitoring, Water treatment process control (deionization, reverse osmosis).
At a glance
- Standard: PN-EN 27888:1999
- Category: Physicochemistry
- Procedure steps: 9
- Total time of stages: 9 min–11 min
- Measurement range: 1 μS/cm – 2000 mS/cm (depending on probe)
- Resolution: 0.1 μS/cm (low range), 0.01 mS/cm (high range)
- Accuracy: ±0.5% of reading (with temperature compensation)
Overview
Electrical conductivity (conductivity) of water is a measure of water's ability to conduct electric current. It depends on the concentration and type of dissolved ions (mineral salts), temperature, and ion mobility. It is expressed in μS/cm (microsiemens per centimeter) or mS/cm.
Conductivity is one of the fastest and cheapest analytical parameters — measurement takes tens of seconds and requires no chemical reagents. It serves as an indicator of total water mineralization: distilled water <1 μS/cm, drinking water 200–800 μS/cm, seawater ~50 000 μS/cm, industrial wastewater may exceed 10 000 μS/cm.
It is a mandatory parameter in drinking water testing (Polish Ministry of Health Regulation — standard ≤2500 μS/cm at 20°C), surface and groundwater monitoring, and wastewater control. Measurement is temperature-sensitive — results are corrected to reference temperature of 25°C (or 20°C according to some standards).
Method principle
The conductometric method is based on measuring the electrical conductivity of a solution between two electrodes (platinum or stainless steel) immersed in the water sample. Application of alternating voltage (AC) at frequency 50–1000 Hz causes ionic current flow through the solution.
The conductivity meter measures specific conductivity (conductivity) as the inverse of resistivity: κ = G × K, where G — measured conductance [S], K — cell constant [cm⁻¹]. The cell constant is determined during calibration with KCl solution.
The result is converted to reference temperature of 25°C using temperature coefficient (typically ~2%/°C): κ₂₅ = κₜ / [1 + α × (t - 25)].
Applications
- Drinking water quality control (limit ≤2500 μS/cm at 20°C)
- Surface and groundwater monitoring
- Water treatment process control (deionization, reverse osmosis)
- Water mineralization assessment (TDS ≈ 0.5–0.7 × conductivity)
- Industrial water quality control (boilers, coolers, pharmaceuticals)
- Rapid assessment of deionized and distilled water purity
Key parameters
| Parameter | Value |
|---|---|
| Measurement range | 1 μS/cm – 2000 mS/cm (depending on probe) |
| Resolution | 0.1 μS/cm (low range), 0.01 mS/cm (high range) |
| Accuracy | ±0.5% of reading (with temperature compensation) |
| Reference temperature | 25°C (ISO 7888) or 20°C |
| Temperature coefficient | ~2%/°C (for typical waters) |
| Measurement time | 30–60 seconds per sample |
Standard
- Standard number
- PN-EN 27888:1999
- Title (PL)
- Jakość wody — Oznaczanie przewodności elektrycznej właściwej
- Title (EN)
- Water quality — Determination of electrical conductivity
Step-by-step procedure
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Workstation preparation
Turn on conductivity meter. Check probe condition (cleanliness of platinum electrodes, no damage). Prepare calibration solutions at room temperature.
-
Calibration
Immerse probe in KCl calibration solution (select concentration for expected sample range). Wait for reading and temperature stabilization. Confirm calibration value. Check cell constant.
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Probe rinsing
Rinse probe with deionized water minimum 3 times. Gently dry with tissue (do not touch electrodes!).
-
Sample preparation
Bring sample to room temperature (20–25°C). Do not filter unless required. Record sample temperature.
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Sample measurement
Immerse probe in sample — electrodes must be completely submerged. Ensure no air bubbles. Wait for reading stabilization (±1% for 30 s).
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Result reading
Record conductivity value in μS/cm or mS/cm. Record measurement temperature. Ensure result is automatically compensated to 25°C (or convert manually).
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Rinsing between samples
Between consecutive samples, rinse probe with deionized water. For large conductivity differences — rinse multiple times until low background achieved.
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Quality control
Every 10 samples measure KCl control solution. Deviation max ±5% from certified value. Check blank (deionized water <1 μS/cm).
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Probe storage
After work, rinse probe with deionized water. Store dry or immersed in deionized water (depends on manufacturer). Do not store in KCl!
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Laboratory conductivity meter | Mettler Toledo FiveEasy F30, WTW inoLab Cond 7110, Hanna HI5321 | 2 500–12 000 PLN |
| Conductivity probe | WTW TetraCon 325, Mettler Toledo InLab 731-ISM, K=0.475–1.0 cm⁻¹ | 500–3 000 PLN |
| Temperature sensor | Integrated with probe (NTC or Pt1000) | built into probe |
| Glass beakers 100–250 mL | DURAN / Simax borosilicate | 15–40 PLN/pc |
| Deionized water | For rinsing probe between measurements, conductivity <0.1 μS/cm | system 15 000–40 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| KCl calibration solution 0.01 mol/L | 7447-40-7 | Conductivity 1413 μS/cm at 25°C. Certified CRM traceable to NIST. For conductivity meter calibration. |
| KCl calibration solution 0.1 mol/L | 7447-40-7 | Conductivity 12 880 μS/cm at 25°C. For calibration in higher range. |
| KCl calibration solution 0.001 mol/L | 7447-40-7 | Conductivity 147 μS/cm at 25°C. For calibration in low range (pure waters). |
| Deionized water | — | Conductivity <0.1 μS/cm, for rinsing probe between samples. |
Health and safety (OHS)
- KCl solutions — low risk, use protective gloves
- Probe — delicate, platinum electrodes — do not scratch
- Safety goggles and laboratory coat required
- Wastewater samples — potentially infectious, use gloves
Training and video materials
Frequently asked questions
Which standard describes this test?
The test is performed according to PN-EN 27888:1999 — “Water quality — Determination of electrical conductivity”.
How does this method work?
The conductometric method is based on measuring the electrical conductivity of a solution between two electrodes (platinum or stainless steel) immersed in the water sample. Application of alternating voltage (AC) at frequency 50–1000 Hz causes ionic current flow through the solution.
What is the measuring range and accuracy?
Measurement range: 1 μS/cm – 2000 mS/cm (depending on probe); Resolution: 0.1 μS/cm (low range), 0.01 mS/cm (high range); Accuracy: ±0.5% of reading (with temperature compensation); Reference temperature: 25°C (ISO 7888) or 20°C.
How long does the test take?
The times given for the individual stages add up to approximately 9 min–11 min. The procedure comprises 9 steps.
What equipment is required?
Laboratory conductivity meter, Conductivity probe, Temperature sensor, Glass beakers 100–250 mL, Deionized water. Indicative cost of the core instrument (Laboratory conductivity meter): 2 500–12 000 PLN.
Where is this test used?
Drinking water quality control (limit ≤2500 μS/cm at 20°C); Surface and groundwater monitoring; Water treatment process control (deionization, reverse osmosis); Water mineralization assessment (TDS ≈ 0.5–0.7 × conductivity); Industrial water quality control (boilers, coolers, pharmaceuticals); Rapid assessment of deionized and distilled water purity.
What safety precautions apply?
KCl solutions — low risk, use protective gloves; Probe — delicate, platinum electrodes — do not scratch; Safety goggles and laboratory coat required; Wastewater samples — potentially infectious, use gloves.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number PN-EN 27888.