As the Philadelphia water department faces continued scrutiny over how it tests for lead, bills introduced by city council members could push the city to the fore in warning residents about the dangers of lead in water.

The bills would require landlords to tell renters about lead piping that connects buildings to the water main, and require daycares and schools to test water for lead contamination. Currently, neither measure is required by federal or local law.

Last week, the Guardian published an investigation that found water departments in 33 cities in 17 states east of the Mississippi river had in the last decade used testing methods that may diminish the amount of lead detected in tests.

Hours after the investigation was published, a class action lawsuit against the city of Philadelphia was announced. The suit alleges that officials were not using the best available water testing methods to detect lead.

“What we’re trying to do is renew a 50-year-old conversation about lead poisoning,” said Helen Gym, sponsor of the bill that would require annual lead-in-water testing in schools.

“We have to do these things in order to remain incredibly vigilant about an incredibly serious issue.”

In Philadelphia, lead contamination has been a problem for decades. There is no safe level of lead, which is especially dangerous in childhood: exposure to even tiny amounts is associated with learning difficulties and behavioral disorders. Some research has even connected lead exposure with the likelihood a child will commit a crime in the future.

The most recent surveillance by the Pennsylvania state health department showed that more than 10% of 35,800 Philadelphia children tested for lead exposure had levels above five micrograms per one-tenth of a liter of blood. The federal Centers for Disease Control and Prevention has cited this as a level at which physicians should increase monitoring of children exposed to lead.

Nationally, most lead surveillance has focused on paint, soil and dust, covering the age at which blood tests are scheduled to take place and how inspectors test the homes of children with elevated lead levels.

Federal law requires landlords to tell tenants if a home contains lead paint, but no such disclosure is required for lead service lines. The Philadelphia health department admitted in public hearings that when investigating the homes of children with elevated lead levels, inspectors do not test water for lead.

The federal Environmental Protection Agency (EPA) does not require schools or daycares to test water for lead, despite more than two decades of elevated lead levels being found in schools around the country. At one time, it was common for water fountains and coolers sold to school districts to have lead-lined tanks and parts.

“I’ve been working on the lead-in-drinking-water issue for 25 or 30 years,” said Erik Olson, director of the health program at the Natural Resources Defense Council.

Regarding the bills now proposed in Philadelphia, he added: “The legislation would actually address several holes in the current system that have existed for decades.”

Olson said problems regarding informing tenants about lead service lines had persisted for decades, and that schools and daycare centers had long been a blind spot in EPA testing.

“We want [children] to be drinking water,” Olson said. “It’s much healthier than sugary drinks, and in fact there are legal requirements under federal law for kids to have access to safe drinking water. Unfortunately, a lot of schools and daycare centers have not been tested.”

Though the Philadelphia water department has not exceeded federal guidelines for system-wide lead contamination, some home tests did exceed federal limits. In its most recent round of testing, in 2014, the city’s water department found one home with 62 parts per billion of lead, more than four times the federal “action limit” of 15 parts per billion. Two more had 35 and 25 parts per billion respectively.

The vast majority of the city’s houses and apartments, 91.6%, were built before the lead paint ban in 1978. Lead plumbing was not banned until 1986.

The city also contends with a number of risk factors for lead exposure in children, including a poverty rate of more than 25%, a large proportion of children younger than seven, and low breastfeeding rates. Lead contaminated water can be especially problematic for the last group, research has shown, because formula is often reconstituted with tap water.

At least 33 lead smelters are believed to have operated in the city. Until the use of lead in gasoline was phased out in the 1970s, vehicle emissions released it. Even recently renovated homes may have leaded-brass faucet fixtures, because Congress allowed up to 8% lead content in brass until 2014. The limit is now 0.25%.

The Philadelphia water department has faced increasing scrutiny since it became clear it told customers to use protocols known to potentially reduce lead in test results.

In 2016, the EPA recommended against three such protocols – running water before a six-hour test period, removing faucet filters and slowly running water. Some practices, such as removing faucet filters called aerators, were warned against in 2006.

Since the Guardian began investigating Philadelphia’s water testing practices, the EPA has said it sent a letter to the city’s water department, urging it to comply with the latest recommendations. It is unclear if the water department intends to do so.

The bills, scheduled to be introduced on Thursday, could be some of the first in the US to require landlords to tell tenants if their water travels through lead service lines. The water department estimates that about 50,000 such lines exist in the city. The bills are unlikely to be passed until the fall, because of a legislative summer break.

Gym, the councilwoman, said the city council wanted to “make sure our water department is working within the boundaries of the latest science and also testing expansively”. She did not say if the water department had dropped the testing practices the EPA has recommended against.