Monochloramine (NH2Cl, CAS 10599-90-3), often called chloramine, is a combined-chlorine secondary disinfectant formed in the water from chlorine plus ammonia at 4.5:1 to 5:1 Cl2:NH3-N by weight. More than one in five Americans drink chloraminated water (US EPA), and the residual is capped at 4.0 mg/L as Cl2, a maximum residual disinfectant level (MRDL) computed as a running annual average under 40 CFR 141.65.
Nothing is bought as monochloramine. Plants dose a chlorine source and an ammonia source, then hold the ratio, the pH above 8.0 and a residual of 1 to 4 mg/L as Cl2 in the network. Its 3-log Giardia CT at 10 °C (50 °F) is 1,850 mg·min/L, about 18 times that of free chlorine, which is why it carries the residual rather than the primary kill. Monochloramine is one of the oxidants in this reference of water treatment chemicals, documented with the same identity, dose and compliance fields as every other entry.
The identity card below summarizes the attributes that define monochloramine.
| Attribute | Value |
|---|---|
| Name | Monochloramine |
| Synonyms | Chloramine, chloramide, combined chlorine (when monochloramine is meant) |
| CAS number | 10599-90-3 |
| EC number | 234-217-9 (ECHA name: chloramide) |
| Formula and molar mass | NH2Cl; 51.47 g/mol |
| Class | Inorganic chloramine (combined chlorine) |
| Functions | Secondary (residual) disinfectant; supplemental disinfectant; bromate control agent in ozonation |
| Supply form | Generated in situ from chlorine (gas or sodium hypochlorite) and ammonia (anhydrous, aqua ammonia, ammonium sulfate or ammonium chloride) |
| Dose basis | mg/L as Cl2 |
| US limit | MRDL 4.0 mg/L as Cl2, running annual average (40 CFR 141.65) |
| WHO | Guideline value 3 mg/L |
| NSF/ANSI/CAN 60 | No listing under its own name; precursors listed |
Every value on this page is checked against primary sources (eCFR, Health Canada, WHO, NSF listings, AWWA, ECHA); see our methodology and fact-checking process.
What Is Monochloramine (NH2Cl)?#
Monochloramine is the first chloramine that forms when hypochlorous acid meets ammonia: NH3 + HOCl → NH2Cl + H2O. Health Canada (2020) places its formation between pH 6.5 and 9.0, fastest at pH 8.3, and the reaction is the basis of every chloramination program.
Monochloramine has a taste threshold of 0.48 mg/L and an odor threshold of 0.65 mg/L for a trained panel (Health Canada, 2020). Consumer complaints appear at 3 to 3.7 mg/L, and aeration does not remove it, unlike volatile free chlorine.
Monochloramine, dichloramine and breakpoint chlorination: which forms when?#
Three inorganic chloramines form, and the Cl2:NH3-N weight ratio and the pH decide which one dominates. The table below compares the 3 species.
| Species | Formula | Forms at (Cl2:NH3-N by weight, pH) | Taste / odor threshold | WHO guideline value |
|---|---|---|---|---|
| Monochloramine | NH2Cl | Up to 5:1; pH 6.5 to 9.0 | 0.48 / 0.65 mg/L | 3 mg/L |
| Dichloramine | NHCl2 | 5:1 to 7.6:1; pH 4.0 to 6.0 | 0.13 / 0.15 mg/L | None set |
| Trichloramine | NCl3 | Below pH 4.4 or near 15:1 | Odor 0.02 mg/L | None set |
Breakpoint: 7.6:1 in theory, 8:1 to 10:1 in practice (Health Canada, 2020); thresholds from a trained panel.
The breakpoint curve runs through 4 zones: A, reducing compounds consume chlorine; B, chloramines form; C, chloramines are destroyed; D, a free residual remains after the breakpoint (Michigan Tech training, 2023). Chlorine demand and the four curve zones are read under breakpoint chlorination.
How Does Monochloramine Disinfect Water?#
Monochloramine disinfects as a slower, weaker oxidant that persists in pipes far longer than free chlorine. The WHO Guidelines for Drinking-water Quality describe it as less powerful, not to be used as a primary disinfectant, and the source of a more stable residual. The Water Quality Association rates it at about 200 times less effective than free chlorine.
Persistence has a price. Monochloramine slowly decomposes, and that autodecomposition releases ammonia that feeds nitrifying bacteria in the network (US EPA nitrification guidance). How CT and log inactivation are calculated is set out under CT values for disinfection.
Why is monochloramine a secondary disinfectant?#
Monochloramine is a secondary disinfectant because its CT for 3-log Giardia inactivation is about 18 times that of free chlorine: 1,850 against 104 mg·min/L at 10 °C (50 °F) (40 CFR 141.74; free chlorine at pH 7.0 and C ≤ 0.4 mg/L). The table below lists the chloramine CT values that EPA tabulates by temperature.
| Temperature | 3-log Giardia, pH 6 to 9 (mg·min/L) | 4-log virus (mg·min/L) |
|---|---|---|
| ≤ 1 °C (34 °F) | 3,800 | 2,883 |
| 5 °C (41 °F) | 2,200 | 1,988 |
| 10 °C (50 °F) | 1,850 | 1,491 |
| 15 °C (59 °F) | 1,500 | 994 |
| 20 °C (68 °F) | 1,100 | 746 |
| 25 °C (77 °F) | 750 | 497 |
Free chlorine: 104 mg·min/L for 3-log Giardia at 10 °C, pH 7.0. Virus credit applies only when chlorine is added before ammonia (40 CFR 141.74; EPA benchmark guidance, 2022).
Plants therefore pair a strong primary step with a monochloramine residual. UV and membranes leave no residual, so WHO advises a small dose of chlorine or monochloramine as a preservative, and systems using chloramines also calculate a virus disinfection benchmark (40 CFR 141 Subpart P). How utilities pair primary and secondary disinfectants across the plant and network is covered under drinking water disinfection.
Where Is Monochloramine Used? Distribution, Building Water and Ozonation#
Monochloramine is used in 3 settings: drinking water distribution, building water systems and ozone treatment. The table below compares dose, feed point and control in each.
| System | Dose as Cl2 | Feed point | Control | Target | Source |
|---|---|---|---|---|---|
| Drinking water distribution | Typically < 2 mg/L leaving the works | Ammonia after the clearwell, chlorine first | Total chlorine, monochloramine, free ammonia, nitrite | 1 to 4 mg/L in the network; Texas minimum 0.5 mg/L | Irish EPA; 30 TAC 290.110 |
| Building water (Legionella) | 1.0 to 4.0 mg/L | On-site generator on cold-water entry or hot loop | Total chlorine or monochloramine, free ammonia | 1 to 2 mg/L residual; Cl2:NH3 3:1 to 5:1; pH 7.5 to 9 | US EPA (2016) |
| Ozonation (bromate control) | Preformed NH2Cl, 1 to 5 mg/L | Before ozone | Bromate | 68 to 87 % bromate reduction (wastewater study) | Morrison et al. (2023) |
Drinking water distribution: secondary disinfection by chloramination#
Distribution systems carry monochloramine at residuals of 1 to 4 mg/L as Cl2, with typically less than 2 mg/L leaving the works (Irish EPA disinfection manual). Health Canada (2020) advises about 2 mg/L leaving the plant and more than 1.5 mg/L at all monitoring points to prevent nitrification, while WHO notes typical supply concentrations of 0.5 to 2 mg/L.
Texas sets a floor of 0.5 mg/L chloramine as total chlorine, with weekly monochloramine and free ammonia and quarterly nitrite and nitrate sampling (30 TAC 290.110). Under the Stage 2 rule, storage management plus chloramines is a best available technology for consecutive systems serving 10,000 people or more (40 CFR 141.64). Conversion, ratio trimming and booster stations are covered under chloramination.
Building water systems: Legionella control#
Building water systems dose 1.0 to 4.0 mg/L as Cl2 from an on-site monochloramine generator on the cold-water entry or the hot loop, aiming at a 1 to 2 mg/L residual in premise plumbing (US EPA Legionella technologies review, 2016). The same review gives a Cl2:NH3 ratio of 3:1 to 5:1 and pH 7.5 to 9. Premise-plumbing programs sit within Legionella control in water systems.
Ozone treatment: bromate control with preformed monochloramine#
Preformed monochloramine at 1 to 5 mg/L as Cl2 dosed before ozone can cut bromate formation by 68 to 87 %, and by up to 92 % at 5 mg/L, in wastewater ozonation reviewed by Morrison et al. (2023). The US bromate MCL is 0.010 mg/L (40 CFR 141.64), so the ammonium-chlorine process is one lever for bromide-rich sources. Bromate formation and ozone doses are covered under ozone in water treatment.
How Is Monochloramine Dosed? Chlorine-to-Ammonia Ratio and Feed#
Monochloramine is dosed at a Cl2:NH3-N weight ratio of 4.5:1 to 5:1, where 5:1 equals 1:1 molar (Health Canada, 2020). The Irish EPA manual designs at 5:1, starts at 4.5:1 with a trace of about 0.02 mg/L free ammonia as NH3, and never goes below 4:1; above 5:1, dichloramine forms.
Every chloramine dose is stated as Cl2. Free available chlorine is Cl2 plus HOCl plus OCl-, combined chlorine is the chloramines, and total residual chlorine is their sum, all as Cl2. Free, combined and total chlorine are defined under chlorine residual.
How do you convert a chloramine dose between Cl2, NH3-N, NH3 and product?#
One mg/L of NH3-N equals 1.216 mg/L as NH3 and 4.72 mg/L as ammonium sulfate (100 %), which contains 21.2 % N (calculated from molar masses). Feed rates follow the operator formulas: kg/d = mg/L × m³/d / 1,000, and lb/day = mg/L × MGD × 8.34 / purity (Florida DEP; EOCP). The worked example below applies them to one plant.
Worked example, calculated. Inputs: flow 10 MGD (37,854 m³/d); dose 2.0 mg/L as Cl2; ratio 4.5:1 Cl2:NH3-N by weight; chlorine source sodium hypochlorite 12.5 trade % (125 g/L available chlorine); ammonia source 40 % ammonium sulfate or 19 % aqua ammonia. Formulas: Florida DEP and EOCP.
| Quantity | Dose | Feed |
|---|---|---|
| Chlorine as Cl2 | 2.0 mg/L | 75.7 kg/d (166.8 lb/day) |
| Sodium hypochlorite, 12.5 trade % | 2.0 mg/L as Cl2 | About 606 L/d (160 gal/d) |
| Ammonia as NH3-N | 0.444 mg/L | 16.8 kg/d (37.1 lb/day) |
| Ammonia as NH3 | 0.540 mg/L | 20.5 kg/d (45.1 lb/day) |
| Ammonium sulfate, 100 % | 2.10 mg/L | 79.4 kg/d (175 lb/day) |
| Ammonium sulfate, 40 % product | 5.24 mg/L as product | 198.5 kg/d (437 lb/day) |
| Aqua ammonia, 19 % | 2.84 mg/L as product | Product-specific density |
For other flows, the chemical dosage and feed rate calculator converts any chlorine or ammonia dose to kg/d and lb/day.
Which feed order and equipment does chloramination use?#
Chloramination feeds chlorine first and ammonia after the clearwell, so the primary contact runs on free chlorine (Irish EPA). The order matters for credit: chloramine virus CT credit applies only when chlorine is added before ammonia (40 CFR 141.74).
Anhydrous ammonia goes through an ammoniator, and aqua ammonia or ammonium sulfate solution through a diaphragm metering pump. Ammonium chloride (CAS 12125-02-9) is a fourth ammonia source with a small share of listings. Solution strengths and MULs of the main ammonia source are on ammonium sulfate (chloramination).
How Is a Monochloramine Residual Controlled and Tested?#
A monochloramine residual is controlled through 8 routine measurements, with total chlorine as the compliance test (Health Canada, 2020). The 8 measurements are listed below.
- Total chlorine, as Cl2 (Standard Methods 4500-Cl D, E, F, G or I; DPD kits where the State approves them, 40 CFR 141.74)
- Monochloramine, by the indophenol method
- Free ammonia, as NH3-N
- Nitrite, the early nitrification signal
- Nitrate
- Heterotrophic plate count (HPC)
- pH
- Temperature
Continuous analyzers are checked against a grab sample at least every 5 days (40 CFR 141.74). Colorimetric halogen analyzers suffer interference from chloramines, so a free-chlorine analyzer reads a chloraminated stream poorly (Veolia Water Handbook, chapter 36).
Which pH keeps monochloramine stable and limits nitrification?#
Monochloramine is stable above pH 8.0 (Health Canada, 2020). Its decay rate roughly doubles for every 0.7 pH unit drop (Thomas, 1987, cited in US EPA nitrification guidance), and the ammonia that decay releases feeds nitrifiers.
Nitrification follows a weak residual: more than 90 % of nitrifying samples had a residual below 2 mg/L (Wilczak et al., 1996). About two thirds of medium and large US chloraminating systems reported nitrification in a 1996 AWWA survey, and Texas has required a Nitrification Action Plan since 2015-07-30 (30 TAC 290.46(z)). Action levels and breakpoint responses belong to chloramination and nitrification control.
What Is Monochloramine Compatible With? Free Chlorine, Membranes and Elastomers#
Monochloramine is incompatible with free-chlorinated water, polyamide membranes and network elastomers, and it reacts with reducing agents. The 4 interaction groups are listed below.
- Free chlorine: blending chloraminated with free-chlorinated water drives an uncontrolled breakpoint, with residual loss, odors and DBPs (Health Canada, 2020).
- Polyamide RO membranes: chloramine is among the agents not recommended for polyamide elements (DuPont FilmTec Reverse Osmosis Technical Manual); polyamide tolerates less than 0.1 mg/L free chlorine. Hydranautics TAB-111 gives its CPA line 50,000 to 200,000 ppm-h of chloramine exposure against 1,000 to 2,000 ppm-h of chlorine before salt passage doubles.
- Elastomers: chloramine degrades rubber gaskets and seals in the distribution network, and surveyed utilities report increased rubber degradation.
- Reducing agents: sodium bisulfite reduces monochloramine; ascorbic acid proved ineffective against monochloramine in one study (Basu and De Souza, 2011).
Biocides that polyamide membranes tolerate are compared under membrane biofouling control.
Which Standards Cover Monochloramine? NSF/ANSI/CAN 60, AWWA and EN for Precursors#
No product standard covers monochloramine itself; AWWA, CEN and NSF/ANSI/CAN 60 cover its precursors. The table below compares the standards and the NSF maximum use levels (MUL, as product) for each precursor.
| Precursor | NSF/ANSI/CAN 60 MUL, as product (NSF listings, 2026-10-21) | AWWA | EN |
|---|---|---|---|
| Ammonium sulfate | Most common 60 mg/L (125 of 231 product-function rows; 44 companies) | ANSI/AWWA B302-23 | EN 12123:2022 |
| Anhydrous ammonia | 5 mg/L on all 31 product-function rows (10 companies) | ANSI/AWWA B305-22 | EN 12126:2022 |
| Aqua ammonia (ammonium hydroxide) | Most common 10 mg/L (109 of 199 rows; 28 companies) | ANSI/AWWA B306-22 | EN 12122:2024 |
| Ammonium chloride | 37 and 167 mg/L (2 rows; 1 company) | None | EN 1421:2022 |
| Sodium hypochlorite | Most common 84 mg/L (273 of 1,551 rows; 178 companies) | ANSI/AWWA B300-24 | EN 901:2024 |
| Chlorine | 30 mg/L (102 of 106 rows; 38 companies) | ANSI/AWWA B301-24 | EN 937:2016 |
| Monochloramine | No listing | No standard; see AWWA B-series standards | No standard; see EN standards for drinking water treatment chemicals |
Is monochloramine NSF/ANSI/CAN 60 certified?#
No: monochloramine has no NSF/ANSI/CAN 60 listing under its own name; it is covered through its listed precursors. NSF lists ammonium sulfate, ammonia and ammonium chloride products under the function "Chloramination", and hypochlorite listings carry a note to monitor residual chlorine, chlorine dioxide, chlorate, chloramine and DBPs in finished water.
Certification matters because NSF/ANSI/CAN 60 is required in 49 US states (NSF survey of ASDWA members). A utility therefore checks each precursor's listing, MUL and facility rather than a monochloramine certificate. How MULs and listings work is covered under NSF/ANSI/CAN 60 certification.
What Is the Regulatory Status of Monochloramine as a Drinking Water Disinfectant?#
Monochloramine is regulated as a disinfectant residual, not as a contaminant: the US Disinfectants and Disinfection Byproducts Rules cover chlorine, chloramine and chlorine dioxide as disinfectants (US EPA). The matrix below shows the status as of 2026-10-22.
| Instrument | Value | Type | Reference |
|---|---|---|---|
| US MRDL | 4.0 mg/L as Cl2 | Running annual average, computed quarterly from monthly averages; compliance 2002-01-01 / 2004-01-01 | 40 CFR 141.65, 141.133 (63 FR 69390, 1998-12-16); disinfectants and disinfection byproducts rules |
| US MRDLG | 4 mg/L as Cl2 | Non-enforceable goal | 40 CFR 141.54 |
| Short-term exception | May exceed the MRDL | Line breaks, storm runoff, source contamination, cross-connection events | 40 CFR 141.2 |
| Consecutive systems | Chlorine and chloramine monitoring | Required from 2009-04-01 | 40 CFR 141 Subpart V; Safe Drinking Water Act |
| DBP rule revisions | No proposal published as of 2026-10-20 | Status | US EPA |
| WHO | 3 mg/L monochloramine; TDI 94 µg/kg bw | Guideline value | WHO guidelines for drinking-water quality |
| Health Canada | No MAC required (2020) | Guideline status | Guidelines for Canadian Drinking Water Quality |
| EU | No parametric value for chloramine; ammonium 0.50 mg/L (indicator); nitrite 0.50 mg/L at the tap, 0.10 mg/L ex works | Directive values | EU Drinking Water Directive 2020/2184 |
| Texas | ≥ 0.5 mg/L chloramine as total chlorine | State minimum | 30 TAC 290.110 |
| US FIFRA | Not covered on this page | Product registration | FIFRA registration of water treatment biocides |
| EU BPR | Precursor: active chlorine released from sodium hypochlorite approved PT1 to PT5, 2019-01-01 to 2028-12-31 | Approval | Implementing Regulation (EU) 2017/1273; EU Biocidal Products Regulation |
| 21 CFR 173.310 | Not listed | Boiler-water additives | eCFR |
The WHO value rests on a tolerable daily intake of 94 µg/kg body weight, derived from a NOAEL of 9.4 mg/kg body weight per day. Disinfection beside coagulation and corrosion control is shown under drinking water treatment chemicals.
Is the 4.0 mg/L chloramine limit an MCL?#
No: 4.0 mg/L as Cl2 is the maximum residual disinfectant level, a running annual average, not an MCL (40 CFR 141.65 and 141.133). Single samples above 4.0 mg/L do not by themselves breach it, and the MRDLG is 4 mg/L as Cl2. WHO sets a 3 mg/L guideline value, and Health Canada sets no MAC.
How Is Monochloramine Handled Safely? Precursor Hazards and Storage#
Monochloramine is never stored or shipped, so its handling hazards are those of the precursors: chlorine, hypochlorite and ammonia, and the reactions between them. Hypochlorite plus ammonia or ammonium salts forms chloramines, and with acid it forms nitrogen trichloride, which decomposed explosively in a drain incident (HSDB 748). The table below compares the precursor hazards and process-safety thresholds.
| Precursor | Reaction hazard | EPA RMP threshold (40 CFR 68.130) | OSHA PSM threshold (29 CFR 1910.119) |
|---|---|---|---|
| Anhydrous ammonia | Incompatible with halogens and strong oxidizers (NIOSH) | 10,000 lb (4,536 kg) | 10,000 lb (4,536 kg) |
| Aqueous ammonia | Incompatible with halogens and strong oxidizers (NIOSH) | 20,000 lb (9,072 kg) at 20 % or greater | 15,000 lb (6,804 kg) above 44 % |
| Chlorine | Reacts explosively or forms explosive compounds with ammonia (NIOSH) | 2,500 lb (1,134 kg) | 1,500 lb (680 kg) |
| Sodium hypochlorite plus ammonia | Forms chloramines; with acid, nitrogen trichloride (HSDB 748) | n/a (reaction hazard) | n/a (reaction hazard) |
| Monochloramine | Per supplier SDS of the precursors | n/a (not stored); see EPA RMP and OSHA PSM | n/a (not stored) |
The 2024 Safer Communities RMP rule is in force; the proposal of 2026-02-24 was not final as of 2026-10-20.
What GHS classification applies to monochloramine?#
Monochloramine has no harmonised CLP Annex VI entry, so its classification is product-specific (ECHA). Because it is formed in the water and never sold, the safety data sheets that apply are those of the ammonia and chlorine products.
What Are the Alternatives to Monochloramine?#
The 2 alternatives to monochloramine are free chlorine and chlorine dioxide. The table below compares them on residual role, CT and limits.
| Disinfectant | Residual role | 3-log Giardia CT at 10 °C (50 °F) | US limit | WHO |
|---|---|---|---|---|
| Monochloramine | Secondary residual; not a primary disinfectant (WHO) | 1,850 mg·min/L | MRDL 4.0 mg/L as Cl2 | 3 mg/L |
| Free chlorine | Primary and residual | 104 mg·min/L (pH 7.0) | MRDL 4.0 mg/L as Cl2 | 5 mg/L |
| Chlorine dioxide | Residual capped by its MRDL | 23 mg·min/L | MRDL 0.8 mg/L as ClO2; chlorite MCL 1.0 mg/L | No guideline value for ClO2 |
Monochloramine vs free chlorine (sodium hypochlorite and chlorine gas)#
Free chlorine is the stronger disinfectant, with a CT about 18 times lower, while monochloramine is the more stable residual. Monochloramine's disadvantages are nitrification, NDMA formation with dimethylamine precursors, elastomer degradation and membrane damage. Free chlorine has a WHO guideline value of 5 mg/L against 3 mg/L for monochloramine, and both share the 4.0 mg/L as Cl2 MRDL. Trade %, MUL range and storage of the liquid chlorine source are on sodium hypochlorite.
Monochloramine vs chlorine dioxide#
Chlorine dioxide is a far stronger primary disinfectant, at a CT of 23 mg·min/L for 3-log Giardia at 10 °C, but it is capped at 0.8 mg/L as ClO2 and its chlorite byproduct at 1.0 mg/L (40 CFR 141.65, 141.64). Both are on the list of agents not recommended for polyamide membranes. Generation routes and chlorite control are covered under chlorine dioxide.
Monochloramine Precursors, Suppliers and Sourcing#
Monochloramine is not sold, so buyers source an ammonia source and a chlorine source and form the disinfectant on site. Each precursor should be bought with an NSF/ANSI/CAN 60 listing for the exact trade name and facility, and with the AWWA or EN standard it meets. Distributors of ammonia and chlorine sources are listed under water treatment chemical suppliers.
Precursor quotes depend on strength and basis, container (cylinder, tote or bulk), annual volume, freight distance, contract term and certification. Send one precursor specification and request quotes for water treatment chemicals on the same basis. The table below lists the precursors by role.
| Role | Chemical | Common forms | Page |
|---|---|---|---|
| Ammonia source | Ammonium sulfate | 40 % liquid; dry crystal | Ammonium sulfate (chloramination) |
| Ammonia source | Aqua ammonia | 19 % and 29.4 % NH3 | Ammonia (aqueous and anhydrous) |
| Ammonia source | Anhydrous ammonia | Liquefied gas, pressure tanks | Ammonia (aqueous and anhydrous) |
| Ammonia source | Ammonium chloride | 2 NSF-listed products | Section of the ammonium sulfate page |
| Chlorine source | Sodium hypochlorite | 12.5 trade % (125 g/L available chlorine) | Sodium hypochlorite |
| Chlorine source | Chlorine | 68 kg (150 lb) cylinders, 1-ton containers | Chlorine gas |
Monochloramine is formed on site and is not sold; no company is a partner of this site.
Where Does Monochloramine Sit Among Oxidants for Water Treatment?#
Monochloramine is the combined-chlorine member of the oxidant family, the one chosen for residual persistence rather than oxidizing power. Chlorine, bromine, ClO2, ozone and peroxygens are compared under oxidants and oxidizing biocides for water treatment. Unlike chloramines, bromamines remain effective biocides, according to Solenis guidance on cooling-tower testing. One safety line belongs here: mixing bleach and ammonia releases chloramine gas (CDC).
Monochloramine FAQs#
What is another name for chloramine?#
Chloramine usually means monochloramine (NH2Cl), also called chloramide; "combined chlorine" covers it when monochloramine is meant.
What is the difference between chloramine and monochloramine?#
Chloramine is the group name for monochloramine, dichloramine and trichloramine; monochloramine is the one that forms at up to 5:1 Cl2:NH3-N and disinfects. Dichloramine has a lower taste threshold, 0.13 mg/L against 0.48 mg/L.
Does monochloramine form disinfection byproducts?#
Yes: monochloramine forms haloacetonitriles, cyanogen chloride, organic chloramines, chloral hydrate and NDMA, among others (WHO). NDMA reaches up to 0.16 µg/L in chloraminated distribution systems. Formation and control of disinfection byproducts are covered on the DBP page.
Which dechlorination chemicals remove monochloramine?#
Sodium bisulfite reduces monochloramine, while ascorbic acid proved ineffective against it in one study (Basu and De Souza, 2011). Holding without chemicals takes 3 to 4 times longer for chloramines than for chlorine. Dose ratios of the dechlorination chemicals are compared on the hub.