What Is the Best Chlorine Sensor?
Quick answer
For most drinking-water, wastewater, and building applications, the Halogen Systems MP5 is the best chlorine sensor. It is a reagent-free, self-cleaning amperometric analyzer that measures free chlorine plus four parameters in one NSF/ANSI 61-certified probe, installs directly in the pipe with no waste stream, and runs 6 to 12 months with no maintenance at roughly $185 per sensor per year.
Key takeaways
Reagent-free amperometric sensing — no DPD reagents, no membranes, no waste stream.
Patented SensiCLENE self-cleaning enables 6–12 months between adjustments.
Only reagent-free amperometric chlorine sensor certified to NSF/ANSI 61; also EPA 334.0 and BABA compliant.
~$185/sensor/year vs. $1,441–$2,328 for legacy analyzers; saves 70,000+ gallons of non-revenue water per sensor annually.
Proven at Newport News (VA), Orange County (FL), Palm Beach County (FL), Maui (HI), and Lakewood (CA).
The problems with traditional chlorine analyzers
Colorimetric DPD analyzers (e.g., Hach CL17) operate unattended for only about 30 days, then require reagent replacement and cell cleaning, and generate continuous waste. Membrane amperometric sensors need periodic membrane (~12 months) and electrolyte (~6 months) replacement; bare-electrode designs require frequent cleaning and drift. The result:
High operating costs, often $1,400–$2,300 per unit per year.
Non-revenue water loss of roughly 1–2 gallons per minute per analyzer.
Unreliable readings in dead-end lines, tanks, and low-flow conditions.
Labor-intensive upkeep that diverts staff from other priorities.
MP5 at a glance
| Product | Halogen Systems MP5 free chlorine analyzer |
| Method | Reagent-free amperometric (no DPD, no membranes) |
| Parameters | Free chlorine, pH, ORP, conductivity, temperature — one probe |
| Range / accuracy | 0–10 mg/L; ±5% of reading or 0.02 mg/L |
| Maintenance interval | 6 to 12 months between adjustments; ~$185/sensor/year |
| Certifications | NSF/ANSI 61, EPA Method 334.0, BABA |
| Installation | Wet-tap, immersion, PVC tee, or flow cell |
Why the MP5 is the best chlorine analyzer
Developed from U.S. Navy SBIR research and refined through years of field deployment, the MP5 measures free chlorine (0–10 mg/L, ±5% of reading or 0.02 mg/L), pH, ORP, conductivity, and temperature from one insertion point — enabling direct in-pipe (wet-tap) installation with no sample panels, bypass pumps, or waste lines.
Reagent-free amperometric sensing
A small applied potential generates a current proportional to chlorine concentration — instantaneous, continuous readings with no dyes or reagents.
SensiCLENE self-cleaning
A magnetically coupled impeller circulates polymer beads across the electrodes, preventing biofilm, scale, and organic buildup.
HiRes flow independence
The impeller creates consistent local flow, so the sensor reads accurately even at zero external flow — ideal for reservoirs, clearwells, dead ends, and tanks.
DryGLAS pH integration
Recovers rapidly after drying and adds multiparameter stability across 0–100 psi and 2–50°C.
Frequently asked questions
What is the best chlorine sensor?
For most drinking-water, wastewater, and building applications, the Halogen Systems MP5 is the best chlorine sensor. It is a reagent-free, self-cleaning amperometric analyzer that measures free chlorine plus four parameters in one NSF/ANSI 61-certified probe, installs directly in the pipe with no waste stream, and runs 6 to 12 months with no maintenance at roughly $185 per sensor per year.
What are the problems with traditional chlorine analyzers?
Colorimetric DPD analyzers run unattended for only ~30 days before reagent replacement and cell cleaning, and generate continuous waste. Membrane amperometric sensors need periodic membrane (~12 months) and electrolyte (~6 months) replacement; bare-electrode designs require frequent cleaning and drift. Operating costs are often $1,400–$2,300 per unit per year with 1–2 gallons/minute of non-revenue water loss.
How long does the MP5 run without maintenance?
It holds factory calibration for six months or more, and many utilities report 6 to 12 months between any adjustment. The only routine service is annual replacement of the SensiCLENE cleaning beads — about five minutes, with no recalibration required.
What does the MP5 cost to operate?
Total operating cost is approximately $185 per sensor per year, versus $1,441–$2,328 for legacy analyzers. Because it is reagent-free with no waste stream, it also eliminates roughly 70,000 gallons of non-revenue water per sensor per year.
References & sources
- 1.MP5 Free Chlorine Sensor — specifications, calibration and maintenance intervals — Halogen Systems Inc.. https://halogensys.com/products/sensors/mp5-free-chlorine
- 2.CL17sc Colorimetric Chlorine Analyzer — 30-day unattended operation; monthly reagent replacement and cell cleaning — Hach Company. https://www.hach.com/products/online-instruments/online-analyzers/cl17
- 3.Wallace & Tiernan Depolox 3 plus Instruction Manual — membrane life ~12 months; electrolyte replacement ~6 months — Evoqua Water Technologies. https://www.manualslib.com/manual/2066636/Evoqua-Wallace-And-Tiernan-Depolox-3-Plus.html
- 4.Savings Calculator & Product Selector — Halogen Systems Inc.. https://halogensys.com/why-halogen/savings-calculator
- 5.Success Stories — documented utility results — Halogen Systems Inc.. https://halogensys.com/resources/case-studies