Shock and continuous chlorination is the most widely used method of disinfecting water in shared systems, mains networks and industrial facilities. It effectively eliminates bacteria, biofilm and microbiological contamination. We carry it out with full sanitary documentation.
Chlorine in water forms hypochlorous acid (HOCl), which passes through the cell membranes of microorganisms and destroys their enzymes and genetic material. It works effectively against bacteria (including Legionella), viruses and fungi.
For shock chlorination we use concentration 20–50 mg/l for 30–60 minutes, which destroys biofilm and disinfects the entire system deeply — including dead legs and capped-off branches of the pipework.
Shock
A single high dose of chlorine (20–50 mg/l). Used after failures, refurbishment, positive test results or when a new system is commissioned.
Continuous
The chlorinator doses chlorine into the system at a constant concentration of 0.1–0.3 mg/l. Ideal for apartment blocks, workplaces and properties on well water.
ClO₂
More effective than chlorine at low doses — a 5× stronger oxidant. It does not form trihalomethanes. Intended for hospitals, hotels and systems with Legionella.
An order to disinfect following a result outside the limits — Legionella, E. coli, enterococci.
New or refurbished water systems — disinfection required before they are put into use.
Domestic and drilled wells — seasonal disinfection, or after flooding or contamination.
Disinfection of balancing tanks, pressure vessels and hot water cylinders after cleaning.
Hotels, hospitals, swimming pools and care homes — mandatory inspections and disinfection in line with the sanitary inspectorate.
A system contaminated after flooding or a mains failure — immediate shock disinfection.
Chlorinating a water system is a procedure, not a one-off pouring of chemicals into a pipe. Effectiveness comes down to concentration, contact time and thorough flushing — and the value to you comes down to the report and the follow-up test result. Here is how it works in practice:
We establish the layout of the system, the draw-off points, cylinders and dead legs where microbiology is most likely to develop. On that basis we plan the scope, the date and how long the water will be off.
It removes deposits and biofilm that shield bacteria and bind chlorine. Without this step disinfection loses its effectiveness, because the agent is consumed by contamination instead of by the microorganisms.
The system is filled with a solution of sodium hypochlorite (NaOCl) or chlorine dioxide at a concentration matched to the purpose of the treatment. We check the concentration at the draw-off points and hold it for the required contact time.
The system is flushed until the chlorine concentration returns to the level required for drinking water. Only then can the water go back into normal use.
We take samples to an accredited laboratory and issue a disinfection report. The complete set of documents is recognised by Sanepid, including at the handover of new installations under PN-EN 806-4.
Chlorination is one of the methods we use as part of water system disinfection. If you are not sure whether your system needs treatment, start with water testing.
Once shock disinfection is complete we flush the system thoroughly until the free chlorine concentration falls to ≤0.3 mg/l — in line with WHO standards and the Ministry of Health regulation on the requirements for water intended for human consumption. We take a follow-up sample confirming that the water is safe.
The exposure itself takes 30–60 minutes. Together with filling the system, exposure and flushing, it usually comes to 2–4 hours depending on the size of the installation. The system is out of use while disinfection is under way.
Chlorination is effective against Legionella pneumophila, although the bacterium can be shielded by biofilm. That is why we combine shock chlorination with mechanical cleaning, or use ClO₂, which penetrates biofilm better. In high-risk properties we recommend combining chlorination with the thermal method.
Yes — after every disinfection we issue full documentation: a completion report, a parameter sheet (Cl concentration, pH, exposure time), a water analysis report confirming effectiveness and a summary report for Sanepid and the sanitary inspectorate. The documents are recognised by the sanitary inspectorates.
Chlorine dioxide (ClO₂) is a five times stronger oxidant than chlorine, works across a wider pH range and does not form trihalomethanes (THMs) — compounds that are potentially carcinogenic. It costs more to use, but is more effective in the presence of biofilm and where water pH is high. We recommend it for hospitals, hotels and properties with a history of Legionella.
We work across Mazovia, Łódź, Podlasie and the Lublin region. We reply the same working day.
