Disposal of Laboratory Wastes to Sanitary Sewer

Guide for Drain Disposal of Laboratory Chemicals


MSU Safety and Risk Management (SRM) prepared this guide with assistance from various resources in the toxicology, chemistry, and environmental sciences.

Staff at the Bozeman Area Waste Water Treatment Plant, the destination of MSU s wastewater, were consulted in developing these guidelines to assure that local government regulations are followed.


Within individual laboratories, authorization for specific operations, delineation of appropriate safety procedures and instruction about these procedures is a responsibility of the principal investigator (PI).

It is the responsibility of each MSU laboratory worker to be sure that chemical waste generated from his or her activities is disposed of properly.  Some materials can be safely let into the sanitary sewer and others can cause damage to health, the environment, or the functioning of the wastewater plant.

Inappropriate chemicals put down the drain may be incorporated into sludge formed in wastewater treatment, contaminating it enough to be classified as a hazardous waste where otherwise it might have been recycled. After treated wastewater leaves the plant, it flows to East Gallatin River, a major recreational and drinking water resource for this area. The stewardship of this important natural resource is our collective responsibility.

Laboratory workers should consult this guide before undertaking drain disposal of any lab chemicals.



Send down the drain only those materials found on the safe list. Compounds not listed are not suitable for drain disposal.


Drain disposal must only be used when the drain flows to a sanitary sewer system* which eventually goes to the wastewater treatment plant. Storm drain systems flow directly into surface water (East Gallatin for example) and should NEVER be used for chemical disposal. Laboratory sinks should be used for disposal of chemicals on the safe list as discussed below.

How Much

Quantities of chemical waste for drain disposal should be limited generally to a few hundred grams or milliliters or less per day.  Larger amounts should have prior approval from Chemical Safety.  Only materials listed as safe for drain disposal in this document are approved for drain disposal in quantities up to 100 grams or 100 milliliter per discharge.  Disposal should be followed by flushing with at least 100-fold excess of water at the sink. (That means for 100 ml of chemical run the water for about two minutes at maximum flow.)


Understand the hazards and toxicity of the materials you work with by consulting material safety data sheets (soon to be available in every department). Work slowly to avoid splashes and wear the proper protective equipment (lab coat, goggles, face shield, gloves) during drain disposal.

*Sanitary sewer is the system of sinks, toilets, drains and associated pipes that send wastewater to a treatment plant where it is biologically and chemically treated before discharge into the environment.

The MSU Chemical Safety Team will collect chemicals that are not appropriate for drain disposal.  See appropriate section.



Ashes, cinders, sand, mud, straw, shavings, metal, glass, rags, feathers, tar, plastics, wood, manure, hair and fleshing, entrails, paint residues, solid or viscous substances capable of causing obstruction to the flow of sewers.

Some chemicals that are not appropriate for drain disposal include:

Halogenated hydrocarbons

Nitro compounds


Flammables (immiscible in water)

Explosives such as azides and peroxides

Water soluble polymers that could form gels in the sewer system

Water reactive materials

Malodorous chemicals

Toxic chemicals such as carcinogens, mutagens, teratogens

Substances that boil below 50 C.

Mixtures that have a component not found on the safe list.

Any material not found on the safe list.


Check with Chemical Safety at 994-3572 if you are not certain about drain disposal for a particular material. We may also be able to provide you with instructions for laboratory detoxification for some materials.




Dilute solutions of inorganic salts where both cation and anion are listed below are suitable for drain disposal.  Materials listed are considered to be relatively low in toxicity. Compounds of any of these ions that are strongly acidic or basic should be neutralized before drain disposal.

Cation    Anions

Al+3  BO3-3

Ca+2  B4O7-2

Fe+2, +3  Br-

H+  CO3-2

K+  Cl-

Li+  HSO-3

Mg+2  OCN-

Na+  OH-

NH4+  I-

Sn+2  NO3-

Sr2+  PO4-3

Ti+3, +4  SO4-2

Zr+2  SCN-


Mineral acids and bases should be neutralized to pH 5.5 to 9 range before disposal, following procedures in Appendix A.


Copper and Zinc have specific discharge limits required by the Sewage Treatment Plant. Contact Chemical Safety at 994-3572 prior to discharging any copper or zinc solutions.


Materials listed below in quantities up to about 10g or 100 ml at a time are suitable for disposal down the drain while flushing with excess water. These materials are soluble to at least 3 percent; present low toxicity hazards and are readily biodegradable.  Larger volumes must be collected by the Chemical Safety Team.


Alkanols with 4 or fewer carbon atoms:



 propanol and isomers

 butanol and isomers

Alkanediols with 7 or fewer carbon atoms

 ethylene glycol

 propylene glycol

 butylene glycol

 butanediol + isomers

 pentylene glycol

 pentanediol + isomers

 hexylene glycol

 hexanediol + isomers

 heptamethylene glycol

 heptanediol + isomers


Alkoxyalkanols with 6 or fewer carbon atoms:






 n-C4H9OCH2CH2OCH2CH2OH (2(2-butoxyethoxy) ethanol)


Aliphatic aldehydes with 4 or fewer carbon atoms:


formaldehyde (10% or less aqueous solution) <100mls per discharge!!

propanal (propionaldehyde)

 butanal (butyraldehyde)




RCONH2 and RCONHR with 4 or fewer carbon atoms and RCONR2 with 10 or fewer carbon atoms:


 N-methyl formamide

 N,N-diethyl formamide

 N,N-dimethyl formamide

 N-ethyl formamide


 N-methyl acetamide

 N,N-dimethyl acetamide

 N-ethyl acetamide


 N-methyl propionamide

 N, N-dimethyl propionamide





Aliphatic amines with 6 or fewer carbon atoms:





N-ethyl methylamine

N-methyl propylamine

dimethyl propylamine


1-ethyl propylamine


methyl butylamine

N-ethyl butylamine





Aliphatic diamines with 6 or fewer carbon atoms:

1,2- or 1,3- propanediamine (1,2- or 1,3- diaminopropane)

*Amines with a disagreeable odor, such as dimethylamine and 1,4-butanediamine should be neutralized, and the resulting salt solutions flushed down the drain, diluted with at least 100 volumes of water. Disposal limit is 100ml of material.

Carboxylic Acids

Alkanoic acids with 5 or fewer carbon atom: *

 formic acid

 acetic acid

 propionic acid

 butyric acid*

 isobutyric acid

 valeric acid*

 isovaleric acid


Alkanedioic acids with 5 or fewer carbon atoms:

oxalic acid (1,2-ethanedioic acid)

malonic acid (1,3-propanedioic acid)

succinic acid (1,4-butanedioic acid)

glutaric acid (1,5-pentanedioic acid)

Hydroxyalkanoic acids with 5 or fewer carbon atoms:


 lactic acid (2- hydroxypropanoic acid)

3-hydroxybutyric acid

2-hydroxy isobutyric acid


Aminoalkanoic acids with 6 or fewer carbon atoms and the ammonium, sodium and potassium salts of these acids.

Amino acids and the ammonium, sodium and potassium salts of these acids.

*Organic acids with a disagreeable odor, such as butyric acids and valeric acids should be neutralized and the resulting salt solutions flushed down the drain, diluted with at least 100 volumes of water. Disposal limit is 100 ml. of material.


Esters with 4 or fewer carbon atoms:

methyl formate

ethyl formate

isopropyl formate

propyl formate

methyl acetate

ethyl acetate

 methyl propionate

Isopropyl acetate


Ketones with 4 or fewer carbon atoms:


methyl ethyl ketone (butanone)

methyl isopropyl ketone (3-methyl butanone)

Sulfonic Acids and the Ammonium, Sodium, and Potassium Salts of these Acids:

methane sulfonic acid, sodium or potassium salt

ethane sulfonic acid, sodium or potassium salt

1-propane sulfonic acid, sodium or potassium salt

1-butane sulfonic acid, sodium or potassium salt

1-pentane sulfonic acid, sodium or potassium salt

1-hexane sulfonic acid, sodium or potassium salt

1-heptane sulfonic acid, sodium or potassium salt

1-octane sulfonic acid, sodium or potassium salt

1-decane sulfonic acid, sodium or potassium salt

1-dodecane sulfonic acid, sodium or potassium salt

1-tetradecane sulfonic acid, sodium or potassium salt

1-hexadecane sulfonic acid, sodium or potassium salt




Do neutralizations in a fume hood behind a safety shield, as fumes and heat may be generated. Wear lab coat or apron, gloves and goggles.

Keep containers cool during process.

Work slowly.

After neutralization is complete, flush to sewer with 20 parts water.

Acid Neutralization

1.      While stirring, add acids to large amounts of an ice water solution of base such as sodium carbonate, calcium hydroxide, or sodium hydroxide for concentrated acids.

2.      When a pH of at least 5.5  and less than 9.0 is achieved, dispose of the solution into the sewer, followed by 20 parts water.

Base Neutralization

1.      Add the base to a large vessel containing water. Slowly add a 1M solution of HCI.

2.      When a pH of less than 9 and greater than 5.5  is achieved, dispose of solution into sewer system followed by 20 parts water.




Oil should be collected locally and stored temporarily in approved and properly marked containers provided by Chemical Safety. The containers must be clearly marked "USED Oil only: No solvents."


When the oil drums are full please contact the Chemical Safety at 994-2711 to obtain information on the disposal of oils.  A contract with a recycling company has been made through facilities.  Chemical Safety must handle the collection and addition to the recycle container.


National Research Council, Prudent Practices in the Laboratory, Handling and Disposal of Chemicals, National Academy Press, 1995.

American Chemical Society, Safety in Academic Chemistry Laboratories, 1995.

Safety Manuals from the Universities of Wisconsin and Cincinnati.

Bozeman Area Sewer Ordinance