A complete technical overview of sodium hypochlorite — applications in water treatment, cleaning and disinfection, plus best practice for safe bulk storage.
Sodium hypochlorite (NaOCl) is one of the most widely used industrial chemicals in the UK. From municipal drinking water disinfection to dairy CIP cleaning and swimming pool sanitation, its broad-spectrum biocidal action and competitive cost per litre make it indispensable. But it is also a reactive, time-sensitive chemical that demands the right storage and handling discipline.
What is sodium hypochlorite?
Sodium hypochlorite is an aqueous solution typically supplied at 14–15% available chlorine for industrial use, or 10–12% for potable water applications. It is a clear, pale-yellow liquid with a characteristic chlorine odour. The active species is the hypochlorite ion (OCl⁻), which is a powerful oxidiser.
Key industrial applications
In water treatment, sodium hypochlorite is dosed to maintain a free chlorine residual that controls bacteria, viruses and biofilm in distribution networks. In food and beverage manufacturing, it is the workhorse of CIP (clean-in-place) cycles, sanitising tanks and pipework between batches. Laundries and commercial cleaning operations use it as a bleach and stain remover, while leisure operators rely on it for swimming-pool and spa disinfection.
Storage best practice
Sodium hypochlorite degrades over time, releasing oxygen and losing strength. The rate of decomposition roughly doubles for every 5 °C rise in temperature, and is accelerated by UV light and trace metal contamination (especially iron, copper and nickel). To preserve strength: store below 20 °C, keep tanks shaded or insulated, use HDPE or lined GRP storage (never bare metal), and rotate stock on a strict first-in, first-out basis.
Bunding and containment
Under UK CIRIA C736 and Environment Agency guidance, bulk hypochlorite tanks must be bunded to 110% of the largest tank’s capacity. Bunds should be chemically resistant, have no drains to surface water, and be inspected regularly. A spill of 15% hypochlorite is corrosive to skin and eyes and will release chlorine gas if mixed with acids — never co-locate hypochlorite and acid storage.
Handling and PPE
Operators decanting or sampling hypochlorite should wear chemical-resistant gloves (nitrile or neoprene), splash goggles, a face shield for bulk transfers, and a chemical apron. Eyewash and emergency shower facilities must be within 10 seconds’ reach of any handling point.
Buying sodium hypochlorite in the UK
Prestige Chemicals supplies UK REACH-compliant sodium hypochlorite at 14–15% w/v in 25 L drums, 1000 L IBCs and bulk tanker quantities, with rapid UK-wide delivery and full technical support on storage and dosing system design.