ChloroKlean BPR Compliant Chlorine Dioxide Disinfectant - UK Supplier

    Chlorine Dioxide vs Chloramine for Drinking Water Systems

    Chlorine dioxide (ClO₂) and monochloramine (NH₂Cl, commonly called 'chloramine') are both used as secondary disinfectants to maintain residual protection through drinking-water distribution networks. Chloramine has low THM and HAA formation and a persistent residual, but requires management of nitrification, NDMA and material compatibility. Chlorine dioxide can provide a measurable residual, forms no chloramines and generally very little THM or HAA; chlorite, chlorate and other by-products require control. Neither chemistry is a reliable Cryptosporidium barrier. Selection depends on the product, source water, system and regulatory conditions.

    Author
    Key Advantage of ClO₂
    Provides residual without forming NDMA, supporting nitrifying bacteria, or threatening dialysis patients. Stronger biofilm penetration.
    By-products
    ClO₂ forms chlorite and chlorate that require dosing control and measurement. Chloramine can contribute NDMA, some THMs/HAAs and nitrate through nitrification; amounts depend on source water and treatment conditions.
    pH Range
    ClO₂ effective at pH 4-10. Chloramine effective pH 7-9; outside this range monochloramine speciation shifts to dichloramine and trichloramine.
    Regulatory Sources
    WHO Drinking-water Guidelines, US EPA Stage 2 D/DBPR, DWI Regulation 31, EU BPR 528/2012 PT5, HSE HSG274 Part 2
    UK Compliance
    Chlorine dioxide is widely used in UK distribution. Chloramine is less common in the UK than the US but is permitted; both are PT5-listed under GB BPR. ChloroKlean Plus L20 is fully BPR-compliant for PT5.
    Comparison Guide

    Chlorine Dioxide vs Chloramine

    Chloramine is used as a secondary disinfectant for distribution residual, but it supports nitrifying bacteria, can form NDMA (a regulated carcinogen), and is unsafe for kidney dialysis without removal. ClO₂ avoids all three issues.

    ClO₂

    Chlorine Dioxide

    • No chloramines; generally very little THM or HAA, with chlorite and chlorate controlled
    • Penetrates biofilm in distribution pipework
    • Effective against Legionella; better than chlorine against Giardia (Cryptosporidium still needs UV or filtration)
    • Does not support nitrifying bacteria growth
    • Safe for systems supplying dialysis or aquaria
    NH₂Cl

    Monochloramine

    • Persistent residual across long distribution networks
    • Lower THM and HAA formation than free chlorine
    • Supports nitrifying bacteria - residual depletes
    • Forms NDMA (regulated carcinogen)
    • Must be removed for dialysis and aquaria

    Detailed Comparison

    Detailed comparison of chlorine dioxide versus chloramine
    FeatureChlorine DioxideChloramine
    NDMA Formation

    None

    Does not nitrosate dimethylamine

    Yes

    Regulated carcinogen; EPA limit 10 ng/L (proposed)

    THM / HAA Formation

    Generally very little

    Control chlorite, chlorate and other by-products

    Low

    Lower than free chlorine but not zero

    Nitrification Risk

    None

    No ammonia released into water

    High

    Releases ammonia; nitrifiers consume residual

    Biofilm Penetration

    Excellent

    Diffuses into and oxidises EPS matrix

    Moderate

    Better than free chlorine; less than ClO₂

    Legionella Efficacy

    Proven (>4-log)

    Sub-ppm residual sufficient

    Limited

    Slow kinetics; biofilm Legionella often survives

    Cryptosporidium Efficacy

    Limited

    Inactivates oocysts only at high CT; DWI does not accept ClO₂ as a Cryptosporidium barrier in private supplies

    Very limited

    Chloramine ineffective at practical CT values

    Dialysis Compatibility

    Direct safe use rare

    ClO₂ also requires removal for dialysis

    Removal required

    Must be removed pre-dialysis; haemolysis risk

    Lead Plumbosolvency

    Low effect

    Minor impact on lead release

    Significant

    Implicated in lead release events (e.g. Flint, MI)

    UK BPR PT5 Status

    Compliant

    Supplied under GB BPR for PT5 (transitional arrangements)

    Compliant

    Also approved active substance under PT5

    When to Choose Each

    Choose Chlorine Dioxide When:

    • Source water has nitrification history or precursors
    • NDMA compliance is marginal or under regulatory scrutiny
    • Hospital, healthcare, or dialysis facility is on the network
    • Existing distribution has documented biofilm or Legionella issues
    • Lead service line replacement is incomplete (plumbosolvency risk)

    Consider Chloramine When:

    • Very long distribution networks requiring extended residual
    • Existing utility chloramination programme is well established
    • Source water has high TOC making free chlorine THM-prone
    • No dialysis or aquarium customers on the network
    • Local regulator specifies chloramine as the secondary disinfectant

    Why Choose ChloroKlean Plus L20

    If you're considering switching to chlorine dioxide, ChloroKlean Plus L20 is purpose-built for industrial and commercial applications.

    BPR PT5 Compliant

    ChloroKlean Plus L20 holds UK GB BPR PT5 compliance for drinking water disinfection. Documented compliance pathway for use in private water supplies and as a secondary residual in distribution.

    No NDMA, No Nitrification

    ClO₂ chemistry does not release ammonia, so it does not feed nitrifying bacteria or form NDMA - two of the most common reasons utilities move away from chloramination.

    Biofilm and Legionella

    Independently tested >4-log Legionella reduction at 0.1-0.5 ppm. Penetrates pipework biofilm where chloramine and free chlorine sit at the surface.

    Regulatory and Scientific References

    This comparison is informed by the following authoritative sources. Always refer to the latest published guidance.

    WHO Guidelines
    World Health Organization (WHO)

    Guidelines for Drinking-water Quality (Chloramines and Disinfectants)

    WHO Guidelines compare chloramine and chlorine dioxide as residual disinfectants, noting chloramine's role in NDMA formation and the nitrification risk in distribution systems.

    View source
    US EPA UCMR / NDMA
    US Environmental Protection Agency

    Unregulated Contaminant Monitoring Rule (NDMA)

    EPA's UCMR programme has tracked NDMA occurrence in US drinking water; chloramination is the dominant precursor pathway. A formal NDMA MCL is under proposal.

    View source
    DWI Guidance
    Drinking Water Inspectorate (DWI)

    Drinking Water Inspectorate - Disinfection Guidance

    DWI guidance on secondary disinfection in UK public supply lists approved chemicals including chlorine dioxide; chloramination is permitted but uncommon in the UK.

    View source
    US EPA Stage 2 D/DBPR
    US Environmental Protection Agency

    Stage 2 Disinfectants and Disinfection Byproducts Rule

    EPA Stage 2 D/DBPR triggered widespread US utility switching from free chlorine to chloramine; subsequent NDMA and nitrification issues are driving renewed interest in chlorine dioxide.

    View source
    HSE HSG274 Part 2
    Health and Safety Executive (HSE)

    Legionella: Technical guidance for hot and cold water systems

    HSG274 Part 2 covers Legionella control in building hot and cold water systems and describes chlorine-dioxide operating considerations; it does not establish universal superiority over chloramine.

    View source

    Frequently Asked Questions

    Chloramine forms substantially fewer THMs and HAAs than free chlorine, which is the main reason many US utilities switched in response to EPA Stage 1 and 2 D/DBPR. The trade-off is higher NDMA formation, nitrification problems, and increased lead release where lead plumbing remains.

    Yes. Monochloramine slowly releases ammonia, which is consumed by nitrifying bacteria to produce nitrite and nitrate. This consumes the chloramine residual, can drive nitrite above drinking water limits, and degrades distribution water quality. Chlorine dioxide does not release ammonia and does not support nitrification.

    Yes, at sufficient concentrations. NDMA is classified by IARC as 'probably carcinogenic to humans'. The US EPA tracks NDMA under UCMR with chloramination as the dominant precursor pathway. ClO₂ does not form NDMA.

    Chloramine is less effective than free chlorine at oxidising and stabilising the protective lead(IV) oxide scale on the inside of lead service lines. The Flint, Michigan crisis is the best-known example. Where lead service lines remain in service, secondary disinfectant choice matters - contact ChloroKlean for guidance on transitioning legacy networks.

    Chloramine has slower kinetics against Legionella than chlorine dioxide and limited biofilm penetration. For Legionella-critical applications under HSG274 Part 2, ClO₂ has substantially stronger documented efficacy. See our hospital Legionella case study.

    Yes. Chlorine dioxide can be dosed at the treatment works to provide a residual through distribution. It is widely used in parts of Europe and permitted in UK public supply under DWI approval. Typical residuals are 0.1-0.5 ppm. Contact ChloroKlean for specification.

    Avoid NDMA and Nitrification Risks

    ChloroKlean Plus L20 delivers BPR PT5-compliant chlorine dioxide for drinking water systems - residual protection without nitrification, NDMA, or biofilm Legionella.