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 is favoured for its low THM and HAA formation and its persistent residual, but has well-documented drawbacks: it supports nitrifying bacteria (which can deplete the residual and degrade water quality), it can form N-nitrosodimethylamine (NDMA, a regulated carcinogen), it is corrosive in some plumbing materials (notably lead-soldered joints and certain elastomers), and it must be removed before kidney dialysis or aquarium use. Chlorine dioxide provides a measurable residual without forming THMs, HAAs, or NDMA, penetrates biofilm in distribution pipework, and is more effective against Legionella and Cryptosporidium. For UK water systems regulated under DWI guidance and ACoP L8, ClO₂ is increasingly specified where chloramine's nitrification or NDMA risks are unacceptable. ChloroKlean Plus L20 is BPR-compliant for PT5 (drinking water) applications.

Author
Key Advantage of ClO₂
Provides residual without forming NDMA, supporting nitrifying bacteria, or threatening dialysis patients. Stronger biofilm penetration.
By-products
ClO₂ produces chlorite and chlorate at regulated low levels. Chloramine produces NDMA (regulated as carcinogenic), some THMs/HAAs, and supports formation of nitrate via nitrification.
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 NDMA, THMs, or HAAs at typical doses
  • Penetrates biofilm in distribution pipework
  • Effective against Legionella and Cryptosporidium
  • 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

None at dose

Does not chlorinate organics

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

Yes (at CT)

Inactivates oocysts at sufficient CT

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

Full GB BPR PT5 authorisation

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)
  • Cryptosporidium resilience is required across the distribution

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
"Chloramine has a real advantage in residual persistence over very long distribution networks - that is the reason US utilities adopted it. The trade-off is the nitrification cycle and NDMA formation, both of which have become regulatory and operational headaches. Chlorine dioxide gives you most of the residual benefit without the nitrification or NDMA risk, and it actually goes after biofilm rather than passing over it. For UK water systems where Legionella and biofilm control are paramount, ClO₂ is the better fit."
GO

Gavin Owen, Managing Director, ChloroKlean

BPR-compliant disinfection specialist

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 supplied from the public mains. Biofilm penetration and residual reliability are emphasised - both areas where ClO₂ outperforms chloramine.

View source

Frequently Asked Questions

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.