Sinks and drains in the lab may seem like a convenient place to dispose of liquids, however in many labs, disposal of chemical solutions and other liquids down sinks and drains is strictly forbidden. The disposal of improper materials in a sink or a drain can cause damage to plumbing systems; interfere with wastewater treatment plant operations; or cause fires, explosions, generation of toxic gases or other adverse chemical reactions. Only under very controlled conditions may some liquid wastes be disposed of down the drain.

Federal, state and/or local regulations control what can be discharged to a sink or drain that flows to an on-site wastewater treatment system or ultimately to a public wastewater treatment plant. It would be very unusual for a lab to have sinks and drains discharge directly to a septic system or directly to surface waters anymore. If that is the case however, it is likely the lab is under strict local regulations or permit requirements as virtually any discharge of material down the sink or drain would reach the environment. Check with your institution’s EH&S department or local regulatory agencies to find out if you can safely dispose of specific waste solutions down the laboratory sink or drain.

The United States Environmental Protection Agency (EPA) regulates point sources that discharge pollutants (from both storm water and non-storm water) into waters of the United States through provisions of the Clean Water Act known as the National Pollutant Discharge Elimination System (NPDES) program. The term “point source” refers to any discernible, confined and discrete conveyance, such as a pipe, ditch, channel, tunnel, conduit, discrete fissure, or container. So if your lab building has an on-site treatment system where the effluent from the treatment system discharges directly or indirectly to a surface water body, it is very likely that a NPDES permit is required.

The U.S. EPA has authorized many states to implement and monitor the NPDES program. NPDES permits set specific requirements regulating the characteristics of the discharged water based on national technology-based effluent limitations and applicable water quality standards. The permits establish the level of performance the discharger must maintain and specify monitoring, inspection, and reporting requirements and other actions necessary to achieve compliance.

If you have an NPDES permit or believe one is required for your facility, continue on to the expanded content to learn more about NPDES permit requirements.