On Tuesday the Washington Aqueduct will return to using chloramine as a disinfectant after a longer than normal treatment using chlorine, according to a press release from the D.C. Water and Sewer Authority.

Normally the switch from using chloramine – made of chlorine and ammonia – to just chlorine is done annually for about a month to keep water mains clean from harmful bacteria. But this year, the treatment that began Feb. 1 lasted more than three months.

The U.S. Army Corps of Engineers determined that the system needed the longer treatment this year, DCist reports.

The use of free chlorine typically causes a change in the taste and smell of D.C.’s tap water.

“Customers may continue to notice a chlorine taste and odor for an additional week before the chloramine reaches the entire water distribution system. This taste may be reduced by refrigerating a pitcher of drinking water overnight,” according to the D.C. WASA press release.