Sodium hypochlorite (CAS 7681-52-9): storage and disposal
From a prep room bottle of household bleach to dental surgery endodontic strengths, sodium hypochlorite is held as a solution across schools, pathology, histology, clinics and veterinary practices. It is classified as corrosive to metals, as causing severe skin burns and eye damage, and as very toxic to aquatic life. Its slow loss of strength and its reactions with acids and ammonia shape storage and collection.
- CAS number
- 7681-52-9
- Form
- Solution
- Storage class
- Alkali
- Signal word
- Danger
- Usual EWC code, laboratory stock
- 16 05 06*
Corrosive
Hazardous to the environment
What to do this week
- Without moving anything that looks damaged, check the label is readable and write down the opened date if it is not already there.
- Check it is stored as alkali stock, and apart from anything listed under "Do not store with" on this page. If nothing is listed, that does not prove it is safe with everything.
- If you no longer need it, add it to your disposal list so it can be included in a collection.
Safe storage in a school or lab
In a school or college prep room, the bottle of bleach tends to end up at the back of a general cupboard. A corrosive store is better: low down, on a resistant tray, with the cap sound. Keep it well away from acid stock, because acids make it release toxic chlorine gas. Ammonia solution and ammonium salts must stay apart too, since hypochlorite with ammonia or amines forms toxic chloramines. Solvents such as acetone are another poor neighbour. Stock ranges from household bleach at about 5% to about 10 to 15% available chlorine, with endodontic strengths in dental surgeries. Because it loses strength with time, hold only what will be used and date each bottle when it arrives.
How to tell it has deteriorated
A sound bottle holds a clear pale yellow liquid with a sharp bleach smell and keeps its shape. What does not look normal is a bulging bottle, a faded colour or crystals on the cap. Bulging comes from oxygen released as the bleach breaks down, which happens faster in warmth and light, so a bottle on a sunny windowsill or beside a radiator ages quickly. Strength falls over months, which means old stock may no longer do the job it was bought for while still being a corrosive waste. A corroded cap, a crust at the neck or damage to the shelf beneath are other signs. Do not squeeze or vent a swollen bottle. Leave it upright on its tray and report it.
How it is disposed of
We arrange this by specialist collection. We do not publish a drain or general waste route for any chemical. It is normally packed in a corrosive alkali laboratory pack with compatible chemicals.
Waste code 16 05 06* is the usual entry for laboratory stock, while a dental surgery or clinic would normally use 18 01 06* and a veterinary practice 18 02 05*, though the producer classifies the waste. Bleach must not go to a sink, a drain, a general waste bin or a skip, whatever has been done with household bleach in the past, and nobody should try to treat it first. The bottles are packed away from acids and ammonia products, in their own compatible group, so a leaking cap never meets either. Record the strength on the label and the number and size of containers, including any that are swollen. The consignment note for the collection is kept for three years.
| Usual EWC code, laboratory stock | 16 05 06* |
|---|---|
| Discarded inorganic chemical, not a laboratory pack | 16 05 07* |
| Human healthcare setting | 18 01 06* |
| Veterinary setting | 18 02 05* |
| Usually classed as hazardous waste | Yes |
The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. Use the waste code finder to see why.
Do not store with
- AcidAcids and alkalis react with strong heat and spattering if they meet.
- OxidiserSome oxidisers react strongly with alkalis, and ammonia based stock is especially at risk.
Named chemicals to keep apart
- Acetic acidHypochlorites release toxic chlorine gas in contact with acids.
- AcetoneHypochlorites react with these solvents, releasing heat and chlorinated products.
- Acetyl chlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Aluminium chlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Ammonia gasHypochlorites and ammonia or amines form toxic chloramine gases.
- Ammonia solutionHypochlorites and ammonia or amines form toxic chloramine gases.
- Ammonium chlorideHypochlorites and ammonia or amines form toxic chloramine gases.
- Ammonium nitrateHypochlorites and ammonia or amines form toxic chloramine gases.
Show 37 more
- Ammonium sulfateHypochlorites and ammonia or amines form toxic chloramine gases.
- AnilineHypochlorites and chlorine releasing agents can react dangerously with aniline through oxidation and chlorination.
- ButylamineHypochlorites and ammonia or amines form toxic chloramine gases.
- Calcium carbideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Calcium metalReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- DiethylamineHypochlorites and ammonia or amines form toxic chloramine gases.
- EthanolHypochlorites react with these solvents, releasing heat and chlorinated products.
- EthanolamineHypochlorites and ammonia or amines form toxic chloramine gases.
- Ethidium bromideReaction with these oxidisers can produce unknown hazardous products.
- EthylenediamineHypochlorites and ammonia or amines form toxic chloramine gases.
- FormalinFormaldehyde reacts with hypochlorite, so the two are stored apart.
- Formic acidHypochlorites release toxic chlorine gas in contact with acids.
- HexamethylenediamineHypochlorites and ammonia or amines form toxic chloramine gases.
- Hydrobromic acidHypochlorites release toxic chlorine gas in contact with acids.
- Hydrochloric acidHypochlorites release toxic chlorine gas in contact with acids.
- Hydroiodic acidHypochlorites release toxic chlorine gas in contact with acids.
- IsopropanolHypochlorites react with these solvents, releasing heat and chlorinated products.
- Lithium aluminium hydrideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Lithium metalReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- MethanolHypochlorites react with these solvents, releasing heat and chlorinated products.
- Nitric acidHypochlorites release toxic chlorine gas in contact with acids.
- Perchloric acidHypochlorites release toxic chlorine gas in contact with acids.
- Phosphoric acidHypochlorites release toxic chlorine gas in contact with acids.
- Phosphorus pentachlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Phosphorus pentoxideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Phosphorus trichlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Potassium metalReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- PyridineHypochlorites and chlorine releasing products can react dangerously with this amine, giving toxic chlorinated products.
- Sodium hydrideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Sodium metalReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Sulfuric acidHypochlorites release toxic chlorine gas in contact with acids.
- Thionyl chlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Tin(IV) chlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Titanium(IV) chlorideReacts with water, releasing heat and often a flammable or corrosive gas, so keep it away from all water based stock.
- Trichloroacetic acidHypochlorites release toxic chlorine gas in contact with acids.
- TriethanolamineHypochlorites and chlorine releasing products can react dangerously with this amine, giving toxic chlorinated products.
- TriethylamineHypochlorites and chlorine releasing products can react dangerously with this amine, giving toxic chlorinated products.
Common quantities
Usually held as: household bleach about 5%, about 10 to 15% available chlorine, endodontic strengths.
Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.
Where it is commonly held
Hazard statements
- H290 May be corrosive to metals.
- H314 Causes severe skin burns and eye damage.
- H410 Very toxic to aquatic life with long lasting effects.
- EUH031 Contact with acids liberates toxic gas.
Precautionary statements
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P264 Wash hands and exposed skin thoroughly after handling.
- P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
- P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P316 Get emergency medical help immediately.
- P317 Get medical help.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P363 Wash contaminated clothing before reuse.
- P391 Collect spillage.
- P405 Store locked up.
- P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
- P234 Keep only in original packaging.
- P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
- P271 Use only outdoors or in a well-ventilated area.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- P319 Get medical help if you feel unwell.
- P332+P317 If skin irritation occurs: Get medical help.
- P362+P364 Take off contaminated clothing. And wash it before reuse.
- P390 Absorb spillage to prevent material damage.
- P403+P233 Store in a well-ventilated place. Keep container tightly closed.
- P406 Store in corrosive resistant container with a resistant inner liner.
Substance as classified, dilutions may differ.
Questions
Is household bleach really treated as hazardous waste?
A weaker product may be less hazardous than a stronger one, but it must not go down a sink or drain, whatever people have done with household bleach. Describe the strength on the label and arrange specialist collection.
Why does an old bleach bottle bulge?
Bleach releases oxygen as it breaks down, faster in warmth and light, so the pressure builds inside a closed bottle. Keep it upright on a tray, do not squeeze or vent it, and report it for collection.
What should it never be stored next to?
Acids, which release toxic chlorine gas, and ammonia, ammonium salts or amines, which give toxic chloramines. Acetone and similar solvents are also kept apart. A separate corrosive store, low down on a tray, is the safer arrangement.
How long can a dental practice keep endodontic stock?
There is no single set period, so follow the expiry date on the product. It loses strength over months, faster in warmth and light, so date each bottle on arrival, store it cool and dark, and ask for collection when stock is old or no longer needed.
