Skip to main content

System Status: 

  1. Home
  2. Safety
  3. Research Safety
  4. Hazardous Waste
  5. Disposal Guidance
  6. Sewer Disposal: What Can Go Down the Drain?

Sewer Disposal: What Can Go Down the Drain?

Last Updated: October 7, 2024 2:30:22 PM PDT
Give feedback

Find out what kinds of liquids can go down UC San Diego drains.

Whatever goes down the drain ends up in the ocean, so the San Diego Metropolitan Wastewater Department strictly regulates sewer waste.

What can go down the drain

The only substances allowed down drains are those that meet all of the following criteria:

  1. Nonhazardous
    • No radioactive waste
    • No hazardous chemical waste
    • No untreated biohazardous waste
  2. Liquid
    • No solids, sludges, or viscous substances
  3. Will not interfere with sewage treatment operations
    • No corrosive pH levels
    • No grease or oil
    • No hot (150°F or higher) temperatures in volumes of more than 10 gallons

Click on a category below to find out if a substance is allowed to go down the drain.

Note: Protect drains from chemical spills — do not use sinks for chemical storage or secondary containment. Disposal of hazardous waste using sinks, intentional evaporation, or as regular trash is against the law. Campus laboratories must abide by strict state and federal waste disposal requirements. You may be held liable for violations of applicable laws.

Type of materials list on the left, and common drain disposal questions on the right
Type of material: Common drain disposal questions:
Lists Materials and whether they can go down the drain, and what to do with it
Material Can it go down the drain?
What to do with it
Biohazardous waste Solids: NO

Liquids: NO, unless they have been deactivated		 Liquid biohazardous waste can be decontaminated and made suitable for drain disposal in 2 ways:
  • Deactivate with bleach (1 part bleach to 9 parts liquid waste) for 30 minutes before pouring it down the drain.
  • Occasionally, liquid waste is autoclaved. Do not add bleach in this case. Read Autoclaving Guidelines for Biohazardous Waste.

For chemical disinfection of liquid biohazardous waste, the only university-wide approved disinfectant for UC San Diego is bleach. If your laboratory wishes to inquire about the use of alternative disinfectants to inactivate liquid biohazardous waste, please send an email with the following information:

  • Material to be disinfected
  • Chemical to be used
  • Concentration of chemical
  • Contact time
  • Disposal method (sewering, hazardous waste pickup)

You will receive a response within five (5) working days regarding approval.

For more information and for disposal instructions for solid biohazardous waste, read How to Package and Dispose of Biohazardous and Medical Waste.
Controlled substances NO Read Controlled Substances: Managing Inventory for disposal procedures.
Radioactive waste NO Read How to Store and Dispose of Radioactive Waste for disposal instructions.
Hazardous chemical waste NO Read How to Identify Hazardous Chemical Waste for guidance on hazardous chemical waste determination. Follow appropriate disposal procedures.
Non-liquids Can it go down the drain? What to do with it
Solids, sludges, or viscous substances NO These items can obstruct the flow of sewage.
Powders and salts NO These items can obstruct the flow of sewage.
Corrosive pH levels Can it go down the drain? What to do with it
Corrosive waste with a pH between 2.0 and 5.0 NO, unless it has been adjusted You have 2 disposal options:
  • Adjust the pH to greater than 5.0 and less than 12.5 and then dispose of it down the drain.
  • Store and dispose of nonadjusted waste as hazardous chemical waste.
Corrosive waste with a pH of 2.0 or lower or pH of 12.5 or higher NO This kind of waste is always considered hazardous chemical waste.
Hot liquids Can it go down the drain? What to do with it
Hot, nonhazardous liquids (150°F or more) NO, unless in volumes of less than 10 gallons For 10 gallons or more of nonhazardous hot liquid:
  • Cool the liquid to below 150°F before pouring it down the drain.
Grease and oil Can it go down the drain? What to do with it
Grease and oil NO, unless the concentration is less than 500 mg per liter For higher concentrations:
  • Dispose of substances such as automotive oil, gear oil, and machinery grease as hazardous chemical waste.
  • Place substances such as vegetable oil, lard, or shortening in the regular trash.
Common questions Can it go down the drain? What to do with it
Alcohols NO, unless the concentration is nonhazardous Ethanol is nonhazardous in concentrations less than 24%. Dilution of higher concentrations of any alcohol is not allowed. For other alcohols:
Ethidium Bromide NO, it cannot go down the drain at any concentration

Because it is highly toxic and mutagenic please take the necessary precautions and dispose of it as hazardous chemical waste.

Read Handling Ethidium Bromide for guidance on safety, management, disposal, and other alternatives
Formalin and formaldehyde NO, unless the concentration is nonhazardous and does not contain methanol or other hazardous chemicals This concentration is nonhazardous and can go down the drain:
  • Formalin solutions containing less than 2.9% formaldehyde
Dilution of higher concentrations is not allowed. For higher concentrations:
Hydrogen peroxide NO, unless its concentration is less than 8% Dilution of higher concentrations is not allowed. For higher concentrations:
Photo and X-ray processor chemicals NO, unless it is spent photo developer not mixed with fixer For concentrated, unused processor chemicals and other spent solutions:
Other chemicals NO, unless the concentration is nonhazardous Some chemicals are hazardous in any concentration. Dilution of higher concentrations is not allowed.
Latex paint NO Read Latex Paint Disposal for disposal instructions.
Oil paint NO Read How to Store and Dispose of Hazardous Chemical Waste for disposal instructions.
Wash and rinse water NO, unless it has not been contaminated by hazardous materials or highly caustic, acidic, or toxic cleaning solutions Read Wash and Rinse Water Disposal for complete information.
For more information, contact the EH&S Environmental Issues Program, (858) 534-3660.
Notice: Disposal of hazardous waste using sinks, intentional evaporation, or as regular trash is against the law. Campus laboratories must abide by strict state and federal waste disposal requirements. You may be held liable for violations of applicable laws.