Public Advocate Jumaane Williams entered office pledging to be an “activist elected official who brings the voices of everyday New Yorkers to city government.”

Judging by his first report as public advocate, Williams appears to be fulfilling that promise. Indeed, he has sought out the voices of people who are normally forgotten and amplified the message to government decision makers. In it, Williams focused on the plight of people living with serious mental illness who end up in a mental health crisis.

His report is both courageous and timely. Tragically, for Rodriguez “Randy” Santos and the four homeless men he allegedly murdered last weekend in the Bowery, Williams’ report comes too late.

But that doesn’t mean it is too late to prevent the next tragedy. And thankfully, Williams’ report flags a host of common-sense solutions most New Yorkers would rightly expect to have already been in place.

First and foremost, the city must address its failing response system. Williams notes that despite calls for “emotionally disturbed persons” nearly doubling from 2009 to 2018, the city has yet to develop a comprehensive strategy for ­responding to those in crisis.

His report illustrates this failure with two especially galling examples. First, he notes that under the current system, not one of the hundreds of thousands of calls to 911 for a mental health crisis annually result in a mobile mental health crisis team being dispatched to ­address the person in need.

To add insult to injury, if a person in need does somehow figure out the 11-digit NYC Well phone number, the city’s crisis teams are only funded to respond within a 48-hour window — far too long in many ­urgent-need cases, in which the threat of self-harm or harm to others is a matter of minutes and hours, not days.

One wonders how a city spending a billion dollars to “reform” mental health services under the auspices of ThriveNYC can justify a full two-day window for crisis response.

It shouldn’t be surprising, then, to note that Santos appears to have touched the criminal and mental health systems many times before allegedly murdering four people. As more facts emerge, it seems Santos was exactly the sort of person Thrive should have been prioritizing for care: He was a ­seriously ill man with a substance-use disorder and a long history of violence. Yet Thrive ends up missing the neediest cases.

Under Williams’ plan, the city would finally move away from crisis care to address people where their needs are. His plan would fund ­respite-care centers, drop-in centers, mental health urgent-care centers and safe havens — the sort of programs that identify people in need of care and reduce the likelihood of crisis. His reform program seems to begin from the premise that serious mental illness, not “stigma,” is the most serious threat to the well-being of the mentally ill and other innocents.

He also calls for more Crisis ­Intervention Training for police and the development of protocols and technology to allow 911 operators, police dispatchers and ­responding officers to identify mental health crisis situations and respond in an appropriate manner that prioritizes de-escalation.

This plan echoes the guidance just released by Crisis Intervention Training International, an internationally recognized group providing training and guidance to communities seeking to de-escalate encounters with the mentally ill. They note that within a well-designed crisis ­response model, “a majority of mental-health calls . . . do not require a law-enforcement response.”

It is too late to know if such a model could have addressed Santos’ needs before tragedy struck. But it is not too late for New York City to prevent the next Santos by implementing these common-sense solutions.

It doesn’t take a mental health expert to tell you that 48 hours is too long to respond to a crisis. It just takes political will. Among ­today’s crop of city elites, it seems, Williams is much closer to real ­solutions than those who most loudly wave the banner of mental health advocacy.

John Snook is the executive director of the Treatment Advocacy Center, a nonprofit that works to eliminate barriers to treatment for people with severe mental illness.