What Is Chlorine?
Chlorine is a widely used oxidizing disinfectant and one of the most important chemicals in modern water treatment. As a halogen, chlorine reacts quickly with microorganisms, making it an effective tool for controlling bacteria, viruses, and algae in a variety of systems.
In treated water, chlorine exists in two primary forms:
- Free chlorine: the active disinfecting species, including hypochlorous acid and hypochlorite ion.
- Combined chlorine: chloramines formed when free chlorine reacts with ammonia or organic nitrogen.
Both forms contribute to total chlorine, but free chlorine is the stronger and more immediate disinfectant. Chlorine has been used since the late 1800s to safeguard drinking water and is still essential today in municipal treatment plants, industrial facilities, cooling systems, and recreational water such as pools and spas.
Why Test for Chlorine?
Monitoring chlorine levels is critical for ensuring that water treatment programs are functioning effectively and safely.
- Disinfection Control: Free chlorine provides the strongest microbial protection, so distinguishing between free and combined chlorine helps operators understand how well the system is performing.
- By‑Product Management: Excess chlorine can contribute to the formation of disinfection by‑products (DBPs), making careful monitoring essential.
- Regulatory Compliance: The Maximum Residual Disinfectant Level (MRDL) for chlorine in drinking water is 4 mg/L.
- Seawater Applications: Total chlorine test kits can also be used to measure total residual oxidizer (TRO) in marine environments.
Accurate chlorine testing ensures that systems remain safe, efficient, and compliant with regulatory standards.
Our Chlorine Test Kits
CHEMetrics offers a comprehensive selection of chlorine test kits designed for both field and laboratory use. All kits feature self‑filling ampoule technology, which minimizes chemical handling and simplifies the testing process.
CHEMets® Visual Chlorine Test Kits
These kits use a color comparator to provide quick, easy‑to‑interpret results.
- DPD chemistry available for both low‑range and high‑range measurement of free and total chlorine.
- High‑range hypochlorite kits for applications where only free chlorine is present.
- ULR CHEMets® using DDPD chemistry for ultra‑low‑range detection—ideal for sensitive applications such as drinking water or ultrapure water systems.
Vacu‑vials® Instrumental Chlorine Test Kits
For users who prefer digital readings, CHEMetrics offers instrumental kits that:
- Use DPD chemistry accepted by the USEPA for drinking water and wastewater analysis.
- Work with CHEMetrics direct‑readout photometers or any spectrophotometer that accepts a 13‑mm round cell.
Instrumental testing provides enhanced precision and supports electronic data logging for quality assurance programs.
Browse Our Kits
All CHEMetrics chlorine test kits, along with a full range of water‑quality testing supplies, are available through the AquaPhoenix Scientific eStore.