A week before the E.P.A.’s letter was released, Alika Speight, 38, and her three children moved into the apartment on the second floor of the house. It is one of a handful of homes the city opened a decade ago to temporarily house families whose children showed high levels of lead in blood tests while city workers scrubbed their homes of lead.

Roughly a year ago, at his annual checkup, Ms. Speight’s 3-year-old son, Kion, showed elevated levels of lead in his blood. The city agreed to remediate her house.

Finding excess lead in Kion’s blood was jarring, she said. Ever since, she has tried to instill new habits in her children. No baths, just fast showers. No food if it is made with tap water. No drinking water unless it comes from a bottle.

But Ms. Speight’s estimate of the number of bottles required to cook and drink far exceeds the two free cases each home can now receive from the city every two weeks.