# Chloramine

> Chloramine (monochloramine) is a long-lasting water disinfectant made from chlorine and ammonia; unlike chlorine, it does not leave water by standing or aerating.

- Canonical: https://genetixbay.com/knowledge/glossary/chloramine.html
- Also written: monochloramine, chloramines, NH2Cl, chloraminated water, combined chlorine
- Glossary category: pH, EC and water · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Chloramine is a disinfectant formed by combining chlorine with ammonia, mainly as monochloramine (NH₂Cl). Many [municipal water](https://genetixbay.com/knowledge/glossary/tap-water.md) systems use it because it lasts longer in pipes than [free chlorine](https://genetixbay.com/knowledge/glossary/free-chlorine.md) and forms fewer disinfection by-products. US regulators set a maximum residual disinfectant level of 4 mg/L (as Cl₂) for both chlorine and chloramine in drinking water; typical levels are lower.

## In practice

Chloramine is stable. Letting water stand overnight or bubbling it does not remove it meaningfully, which is the key difference from free chlorine. At drinking-water levels its direct effect on cannabis roots is probably small, but growers running [living soil](https://genetixbay.com/knowledge/glossary/living-soil.md) or [beneficial-microbe reservoirs](https://genetixbay.com/knowledge/glossary/beneficial-microbe-reservoir.md) worry about effects on microbes. Evidence in cannabis is thin (*Grower practice* concern).

Removal options:

- Ascorbic acid (vitamin C) neutralises chloramine quickly; about 2.5 parts ascorbic acid per part chlorine is a commonly cited ratio (USDA Forest Service), so a pinch per large reservoir is enough.
- Catalytic [activated carbon filters](https://genetixbay.com/knowledge/glossary/carbon-filter.md).
- [RO](https://genetixbay.com/knowledge/glossary/ro-water.md) systems with a catalytic carbon pre-stage.

Find out what your supplier uses from its water-quality report.

## Don't confuse with

- **Free chlorine**: evaporates from standing water within a day or so.
- **Chloride**: the ion Cl⁻, a [micronutrient](https://genetixbay.com/knowledge/glossary/micronutrient.md), not a disinfectant.

## Myth check

"Leave tap water out for 24 hours to remove chlorine" does not work for chloramine. *Established*.

## Related terms

[Free chlorine](https://genetixbay.com/knowledge/glossary/free-chlorine.md), [Tap water](https://genetixbay.com/knowledge/glossary/tap-water.md), [RO water](https://genetixbay.com/knowledge/glossary/ro-water.md), [Living soil](https://genetixbay.com/knowledge/glossary/living-soil.md)

## Read more

- [Water quality for cannabis: RO vs tap, alkalinity, bicarbonates and chloramine](https://genetixbay.com/knowledge/ph-ec/water-quality.md)

## Sources

1. Water Quality Association. 2014. Chloramine fact sheet. https://wqa.org/wp-content/uploads/2022/09/2014_Chloramine.pdf
2. USDA Forest Service. Vitamin C dechlorination. https://www.fs.usda.gov/t-d/pubs/html/05231301/05231301.html