Last month, a leaking sewer line caused thousands of gallons of raw, untreated sewage to spill into an Oxon Hill, MD neighborhood — and into the Potomac River.

Crews from the Washington Suburban Sanitary Commission first discovered the leak on Sunday, May 3, WTOP reported. By the time they were able to repair the leak, more than 15,000 gallons of sewage had leaked. WSSC officials explained that sewer mains are much more difficult to repair than water mains.

“Fixing a broken sewer main is very different than fixing a broken water main,” Lyn Riggins, a spokeswoman for WSSC, said. “You can’t just shut off the waste water. The waste water has to keep flowing or it will back up somewhere.”

Before repair work could begin on the 14-inch crack in the sewer line, which was buried 12 to 24 inches below ground, WSSC contractors had to set up 7,000 feet of temporary pipeline to divert the waste water around the leak and keep sewage moving.

Crews also used a camera to inspect the pipeline before repair work commenced.The entire repair process took about a week — and the leak continued throughout this time.

Because Oxon Hill is located in a low-lying area, much of the leaked sewage was contained. However, some of the sewage made it to the Oxon Run tributary, which flows directly into the Potomac.

Despite the massive sewage leak, officials urged nearby homeowners that their water was still safe to drink, as the sewage and waste water treatment system is separate from the plant that treats drinking water. Residents were encouraged not to walk near areas where sewage had leaked; the WSSC had set up warning signs to indicate these areas, WUSA reported.

“Even though there is waste water leaking in this area, the drinking water system is safe,” Riggins said.