In February 2021 a lye setpoint at a Florida water plant was raised 111-fold and put back within minutes. The sheriff described an intruder. The FBI later said it could not confirm one. Both accounts still stand.
Oldsmar is among America’s most cited water incidents and least settled. Its record rests on a sheriff’s press conference, a federal advisory that never named the plant, and a state advisory that never named its source. In 2023 the FBI said it could not confirm a targeted intrusion, and archived copies show the advisory later gained that sentence with no revision logged. Not confirmed is not disproven.
What survives either account is the architecture. A control system accepted a sodium hydroxide setpoint 111 times its normal value. On the record, what stood between that number and the process was an operator who happened to be watching; by the advisory’s account, the SCADA alarm came after he had corrected it. Controlled remote access answers the intruder account. Limits in the controller and the pump answer both. That reading is BlastWave’s analysis, not a finding.
What is not known: Nobody has shown whose hand changed the setpoint. The sheriff described an outside actor; the FBI later said it could not confirm a targeted intrusion; a former city manager said investigators suspected an employee. No forensic report has been published and the sheriff’s case is still open. The vector was never confirmed: the federal advisory calls weak passwords and an old operating system likely. TeamViewer, a shared password and Windows 7 trace to a Massachusetts advisory that names no source. Whether the pump could deliver the new dose is on no public record.
Recommendation
Take the path away No desktop sharing tool on an operator console answers the internet. A remote session exists only when a named person asks, for a set window, to one application.
Remove standing authority over values End shared credentials and bound chemical setpoints in the controller and the pump, so no keyboard, remote or local, can command a dose the plant should never run.
Let watchers read it one way Staff reportedly took the morning session for a supervisor checking in. Monitoring from elsewhere needs a view, not a path that can write a setpoint.
Sources: AA21-042A (FBI, CISA, EPA, MS-ISAC), 11 Feb 2021, current text via IC3; Pinellas County Sheriff release 21-015, 8 Feb 2021; MassDEP water supplier advisory, undated; FBI to CyberScoop, 10 Apr 2023; Route Fifty, 21 Mar 2023. Full list with links.
Soft Spots: Both causes rest on spoken statements, not documents. The amendment window (absent 22 Mar, present 6 May 2023) is from archive captures not re-read in validation. The architecture reading is BlastWave’s analysis.
The full record
Every claim numbered to its source. Last updated .
A lye setpoint raised 111-fold and put back within minutes, an intruder the sheriff described and the FBI later could not confirm, and a federal advisory that changed without notice. What is verified, what is only reported, and what is still unknown.
Summary
On 5 February 2021, an operator at the water treatment plant in Oldsmar, Florida saw the sodium hydroxide setpoint raised from 100 to 11,100 parts per million, a factor of 111, and reversed it within minutes. The treatment process was unaffected. The sheriff described an intruder; in 2023 the FBI said it could not confirm one. The cause remains contested.2,3,4
Timeline of the Oldsmar incident and its record
Every date is tied to a source. Press reporting appears only as evidence of what was said.
An operator at the Oldsmar water treatment plant sees the sodium hydroxide setpoint on his SCADA screen raised from 100 to 11,100 parts per million, a factor of 111, and puts it back within minutes.1,3
According to the sheriff's office, the plant's system was remotely accessed twice that day, at 8:00 a.m. and 1:30 p.m., "by an unknown suspect." Whether a remote session caused the change is contested.1
A browser on an Oldsmar city network visits a compromised water contractor website. Dragos reported on 18 May 2021 that the code delivered no exploit, and stated medium confidence that it "did not directly compromise any organization."6
Pinellas County Sheriff Bob Gualtieri announces the incident. He describes someone who, "at least it appears on the surface," was trying to do something bad, and says the public was not in danger. City Manager Al Braithwaite tells CyberScoop: "We've obviously disabled the program that enabled it to happen."1,3,7
The FBI, CISA, EPA and MS-ISAC publish joint advisory AA21-042A, "Compromise of U.S. Water Treatment Facility." It does not name Oldsmar, gives no dosage figures and does not confirm the access vector. Its revision history lists one later change, a PDF update on 12 February 2021.2
A republication of the advisory's web text ends the TeamViewer sentence at "access to the system," without the "cannot be confirmed" clause the current text carries.8
Archived copies of the advisory's web page do not carry the FBI's non-confirmation sentence.9
At a public administration conference, former city manager Al Braithwaite calls the incident a "non-event" and says investigators suspected an employee. Route Fifty reports his remarks on 21 March.5
The FBI tells CyberScoop it "was not able to confirm that this incident was initiated by a targeted cyber intrusion of Oldsmar." The sheriff's office says the case is still open.4
Local TV headlines its report "FBI and former city manager say Oldsmar cyberattack never happened." The FBI had said it could not confirm an intrusion, not that none occurred.4,10
An archived copy of the advisory page now carries the FBI's sentence. No revision is logged, and the title still reads "Compromise."2,9
A Congressional Research Service report still describes Oldsmar as a cyberattack, without the FBI's caveat.11
Written testimony to the House Homeland Security Committee says Oldsmar was hacked through its TeamViewer software.12
Key facts and their status
Verified sworn, filed or published by the primary party. Reported rests on press, researchers or unnamed sources. Undisclosed no one has stated it.
Question
What the record says
Status
What changed on the screen?
The sodium hydroxide setpoint, from 100 to 11,100 ppm: a factor of 111, not 1003
No. The treatment process "remained unaffected and continued to operate as normal"2
Verified
Was there an outside intruder?
Described by the sheriff in 2021; the FBI could not confirm a targeted intrusion in 20233,4
Contested
What did the FBI say?
It "was not able to confirm" a targeted cyber intrusion. Not a finding that nothing happened2,4
Verified
Was it an employee?
One former city manager's account, from memory, with no document5
Contested
How was the system reached?
Unconfirmed. Federal advisory: weak passwords and an old operating system "likely"; TeamViewer "may have been used"2
Unconfirmed
TeamViewer, a shared password, 32-bit Windows 7, no firewall?
From an undated Massachusetts state advisory that names no source; not federal findings2,13
Reported only
Was the federal advisory changed?
Yes. The FBI sentence appeared between 22 March and 6 May 2023, with no revision logged2,9
Verified (window, not a date)
Who was the actor, if any?
None identified. No forensic report published; the sheriff's case is still open4
Undisclosed
Incident cost
Not published
Undisclosed
Was the Oldsmar water plant really hacked?
That has never been established, in either direction. The sheriff who announced the incident on 8 February 2021 described an outside actor, and hedged it on the day:
"This is somebody that is trying, at least it appears on the surface, to do something bad."
His office's written release said the plant's system was remotely accessed at 8:00 a.m. and 1:30 p.m. "by an unknown suspect."1 No actor was ever identified. In April 2023 the FBI said it could not confirm a targeted intrusion, and the sheriff's office said: "The case is still open and no further information will be disclosed."4 On the public record, the sheriff has neither retracted nor defended his 2021 account. No party has published a forensic report.
What moved the cursor on the operator's console is the contest. That the setpoint value changed, and that the operator put it back, is not disputed in any account.2,3
Did the FBI say the Oldsmar hack never happened?
No. The FBI said it could not confirm a targeted cyber intrusion, which is the language of an inconclusive investigation, not a finding that nothing happened.
"...through the course of the investigation the FBI was not able to confirm that this incident was initiated by a targeted cyber intrusion of Oldsmar."
The employee account comes from one person. Speaking at the American Society for Public Administration conference on 20 March 2023, Oldsmar's former city manager said:
"The FBI concluded there was nothing, no evidence of any access from the outside, and that it was likely the same employee that was purported to be a hero for catching it, was actually banging on his keyboard."
He spoke from memory, with no document. In February 2021 he had told CyberScoop: "We've obviously disabled the program that enabled it to happen."3 Setting those two statements side by side is BlastWave's juxtaposition; it is not a claim that either is false. The FBI's own words are narrower than his paraphrase of them, and narrower than the local TV headline that followed: "FBI and former city manager say Oldsmar cyberattack never happened."10
In every version, the operator comes out well. In 2021 he caught it. In the 2023 telling, even the former city manager said: "The good news was he fixed it in two minutes."10
How did someone get into the Oldsmar system? Was it TeamViewer?
The way in was never confirmed. The joint federal advisory says the actors "likely accessed the system by exploiting cybersecurity weaknesses, including poor password security, and an outdated operating system."2 On TeamViewer, the advisory as it reads today says:
"Early information indicates it is possible that a desktop sharing software, such as TeamViewer, may have been used to gain unauthorized access to the system, although this cannot be confirmed at present date."
The 2021 copies of the advisory, and a 12 February 2021 republication of its web text, end that sentence at "access to the system."2,8 The qualifier is quoted here as the advisory's current wording, not its 2021 wording. The advisory names no shared password, no firewall and no Windows 7 at the plant; Windows 7 appears only in its general end-of-life guidance.2
The four famous specifics, TeamViewer as the way in, one shared password for remote access, 32-bit Windows 7 and no firewall, come from an advisory by the Massachusetts Department of Environmental Protection. It is not an investigating body, the page carries no date, and it names no source.13 Nobody has disputed those details, and nobody has substantiated them. TeamViewer is not RDP, and no account of Oldsmar involves RDP.
Two further details are often attached to the vector. Staff reportedly took the morning session for a supervisor checking in; that is a press paraphrase of the press conference, not in the written release.14 And a browser on an Oldsmar city network visited a compromised water contractor website at 9:49 a.m. ET that morning. Dragos found that the code delivered no exploit and stated medium confidence that it "did not directly compromise any organization."6 Dragos neither found the vector nor debunked the link.
Was the federal advisory on Oldsmar changed?
Yes. Sometime between 22 March and 6 May 2023, advisory AA21-042A gained the FBI's non-confirmation sentence, and no revision was logged. Archived copies of the advisory page from 17 and 22 March 2023 do not carry the sentence; a copy from 6 May 2023 does.9 The 2021 copies held by Massachusetts, South Carolina and Vermont do not carry it.2
"Through the course of the investigation, the FBI was not able to confirm that this incident was initiated by a targeted cyber intrusion."
The revision history still lists two entries, both from February 2021: the initial version on 11 February and a PDF update on 12 February. The title still says "Compromise," and the body still refers to "unidentified cyber actors." The FBI's own IC3 copy carries the new sentence under the same 11 February 2021 header, with no revision note.2 The captures bracket the change; they do not date it, and the reason for it is not on the record.
The citation chain never caught up. A Congressional Research Service report of 3 June 2025 still describes Oldsmar as a cyberattack without the FBI's caveat,11 written testimony to the House Homeland Security Committee on 22 July 2025 says it was hacked through TeamViewer,12 and a national laboratory case study of the incident is still online.15
Was the Oldsmar water ever dangerous?
No harm is on the record, in either account. The sheriff said on the day:
"At no time was there a significant adverse effect on the water being treated. Importantly, the public was not in danger."
His office's written release puts it slightly differently: "At no time was there a significant effect on the water being treated, and more importantly the public was never in danger."1 The federal advisory says the SCADA software "detected the manipulation and alarmed due to the unauthorized change" only after the operator had corrected it, and that the treatment process "remained unaffected and continued to operate as normal."2Oldsmar's mayor, Eric Seidel, said at the press conference that redundancies in the system would have caught the change in the pH level.16
The number is 111, not 100: 100 to 11,100 parts per million is a factor of 111. Language such as "lethal dose," "mass casualty" or "poisoning" stated as fact goes further than even the 2021 account. Whether the plant's feed pump could physically have delivered the new dose is on no public record.
What is still not known about Oldsmar
Whose hand changed the setpoint: an outside actor, as the sheriff described in 2021, or an employee, as a former city manager said in 2023.3,5
Whether any outside actor existed. None has been identified, no forensic report has been published, and the sheriff's case is still open.4
How the system was reached, if remotely. The federal advisory judges weak passwords and an old operating system "likely" and never confirmed TeamViewer.2
Where the Massachusetts advisory's TeamViewer, shared password, Windows 7 and firewall details came from. It names no source.13
The day the federal advisory gained the FBI's sentence, and why. The archived captures give only a window, 22 March to 6 May 2023.9
Whether the feed pump could physically have delivered 11,100 ppm, and whether the operator screen had any bound on the setpoint.
Any cost to the City of Oldsmar.
Claims about Oldsmar the record does not support
Widely repeated claim
What the record says
"A hacker tried to poison Oldsmar's water."
An intruder was described by the sheriff, never identified, and later not confirmed by the FBI. The sheriff said the public was not in danger.3,4
"FBI and former city manager say Oldsmar cyberattack never happened."
The FBI said it "was not able to confirm" a targeted cyber intrusion. That is inconclusive, not exculpatory, and the sheriff's case is still open.4,10
"An employee caused it."
One former official's account from memory, with no document, in tension with his own February 2021 statement.3,5
"A water treatment facility in Oldsmar, Florida was hacked through its TeamViewer remote-management software over the internet."
The federal advisory says TeamViewer "may have been used"; its current text adds "although this cannot be confirmed at present date." The specifics trace to a Massachusetts advisory that names no source.2,13
"Federal investigators found a shared password, Windows 7 and no firewall."
Those details are the Massachusetts Department of Environmental Protection's, not federal findings. The federal advisory names none of them at the plant.2,13
"Oldsmar shows the risk of unsecured RDP."
TeamViewer is not RDP, and no account of Oldsmar, federal, state or local, involves RDP.
"The lye level was raised a hundred-fold."
100 to 11,100 parts per million is a factor of 111.3
"A lethal dose was narrowly stopped."
The sheriff said the public was not in danger, and the advisory says the treatment process was unaffected.2,3
"Dragos found how the attacker got in" or "Dragos debunked the link."
Neither. The watering-hole code delivered no exploit; Dragos stated medium confidence it "did not directly compromise any organization."6
Including our own. Our Volume 1 Hackopedia entry gave the access vector as an inactive TeamViewer account, stated as fact, and titled the entry an unsecured RDP risk; TeamViewer is not RDP. Our Volume 1 blog said "lethal dose," "mass poisoning" and "mass casualty event," which go further than the sheriff's own 2021 words. This entry corrects all three and marks the record Contested. We correct our own record first; it is what earns the right to correct anyone else's.
BlastWave analysis: the limit that holds in both versions
Analysis, not a disclosed fact
What survives either account is the architecture. A control system accepted a sodium hydroxide setpoint 111 times its normal value, and nothing on the record refused it. A person caught it first; the advisory says the SCADA software alarmed only after he had corrected it, and the downstream pH alarms the sheriff and mayor described detect a change after it is made rather than bound it.2,14,16 Controlled remote access answers the intruder account. Engineering limits in the controller and in the physical sizing of the pump answer both.
The advisory's own mitigations make the same argument: pump sizing, reservoir sizing and valve gearing, so that "if cyber actors gain control of a sodium hydroxide pump, they will be unable to raise the pH to dangerous levels."2 Whether this plant had any such limit is on no public record. In every version, the person who put it right is the same person. That reading of the architecture is BlastWave's analysis, not a disclosed finding.
Podcast: “The Mixing Valve” (9:30). Joe Baxter and Cam Cullen on why a limit the controller and the pump enforce answers both versions of Oldsmar, while remote access controls answer only one.
Video: Oldsmar Short (60 to 90 seconds).
Frequently asked questions
What happened at the Oldsmar water treatment plant?
On 5 February 2021, an operator at the water treatment plant in Oldsmar, Florida saw the sodium hydroxide (lye) setpoint raised from 100 to 11,100 parts per million, a factor of 111, and put it back within minutes. The Pinellas County Sheriff said on 8 February 2021 that the public was not in danger. Who or what changed the setpoint has never been established, and the record is contested.
Was the Oldsmar water plant really hacked?
It has never been established either way. Sheriff Bob Gualtieri described an outside actor in February 2021, hedging that it appeared so "on the surface." In April 2023 the FBI said it was not able to confirm that the incident was initiated by a targeted cyber intrusion, and the sheriff's office said the case is still open. No actor has been identified and no party has published a forensic report.
Did the FBI say the Oldsmar hack never happened?
No. The FBI told CyberScoop in April 2023 that it "was not able to confirm that this incident was initiated by a targeted cyber intrusion of Oldsmar." That describes an investigation that could not establish an intrusion, not a finding that none occurred. A local TV headline in April 2023 said the FBI and the former city manager said the cyberattack never happened; the FBI's own words do not go that far.
Was the Oldsmar incident caused by an employee?
That account comes from one person. At a conference on 20 March 2023, former Oldsmar city manager Al Braithwaite said investigators thought an employee had been banging on his keyboard, as Route Fifty reported. He offered no document, and in February 2021 he had told CyberScoop the city had "obviously disabled the program that enabled it to happen." Employee error is unproven, just as an outside intruder is.
Did the Oldsmar attacker get in through TeamViewer?
The way in was never confirmed. Joint advisory AA21-042A, issued by the FBI, CISA, EPA and MS-ISAC on 11 February 2021, says the actors likely exploited poor password security and an outdated operating system, and that desktop sharing software such as TeamViewer may have been used. The widely repeated TeamViewer, shared password, 32-bit Windows 7 and no-firewall details come from an undated Massachusetts state advisory that names no source.
Was anyone in danger from the Oldsmar setpoint change?
No harm is on the record. The sheriff said on 8 February 2021 that "at no time was there a significant adverse effect on the water being treated" and that the public was not in danger. The federal advisory says the treatment process remained unaffected and continued to operate as normal. Whether the plant's pump could physically have delivered the higher dose is not on any public record.
Was the federal advisory on Oldsmar changed?
Yes, without a logged revision. Archived copies of advisory AA21-042A on cisa.gov lack the FBI's non-confirmation sentence on 17 and 22 March 2023 and carry it by 6 May 2023. The revision history still lists only two entries from February 2021, and the title still says "Compromise." The exact date of the change and the reason for it are not on the public record.
Primary sources are the joint federal advisory AA21-042A and its 2021 copies, the Pinellas County Sheriff's written release, the Massachusetts state advisory, congressional documents and Dragos's published research. The sheriff's spoken words, the FBI's 2023 statement and the former city manager's account reached the public through press reports, which are cited as evidence of what was said.
GovernmentPinellas County Sheriff's Office, release 21-015, "Detectives Investigate Computer Software Intrusion at Oldsmar's Water Treatment Plant." Its wording: "At no time was there a significant effect on the water being treated, and more importantly the public was never in danger." pinellassheriff.gov
FederalFBI, CISA, EPA and MS-ISAC, Joint Cybersecurity Advisory AA21-042A, "Compromise of U.S. Water Treatment Facility," 11 February 2021 (revision history: 11 February 2021 initial version; 12 February 2021 update to PDF file). Current text, read through the FBI's co-published IC3 copy, whose header still reads 11 February 2021 with no revision note; 2021 copies held by Massachusetts, South Carolina and Vermont do not carry the FBI sentence or the "cannot be confirmed at present date" clause. cisa.gov · FBI IC3 copy (PDF) · 2021 copy, Mass.gov (PDF) · 2021 copy, South Carolina (PDF)
PressSean Lyngaas, CyberScoop, "Hacker breached Florida water facility to alter sodium hydroxide level, police say," 8 February 2021. Cited for the sheriff's spoken words at the press conference, the 100 and 11,100 ppm figures, the city's population figure and the city manager's remarks. cyberscoop.com
PressChristian Vasquez, CyberScoop, "Did someone really hack into the Oldsmar, Florida, water treatment plant? New details suggest maybe not," 10 April 2023. Cited for the FBI's and the Pinellas County Sheriff's Office's statements. (The article renders the setpoint as 11,000; the sheriff's figure is 11,100.) cyberscoop.com
PressChris Teale, Route Fifty, 21 March 2023, reporting the former city manager's remarks at the American Society for Public Administration annual conference on 20 March 2023. Cited as evidence of what was said. route-fifty.com
ResearcherDragos, "When Intrusions Don't Align: A New Water Watering Hole and Oldsmar," 18 May 2021. dragos.com
PressJack Evans, Tampa Bay Times, 8 February 2021, reporting the press conference given by Sheriff Bob Gualtieri with Oldsmar Mayor Eric Seidel and City Manager Al Braithwaite.
PressThe RISKS Digest, volume 32, issue 49, 12 February 2021, republishing the US-CERT web text of AA21-042A. Cited as evidence of the 2021 wording. catless.ncl.ac.uk
FederalInternet Archive, captures of the AA21-042A advisory page on cisa.gov, 17 and 22 March 2023 (without the FBI sentence) and 6 May 2023 (with it).
PressAdam Walser, WFTS Tampa Bay 28, "FBI and former city manager say Oldsmar cyberattack never happened," 11 April 2023. Cited as evidence of what was said, and as a specimen of the overcorrection. tampabay28.com
FederalCongressional Research Service, report R48556, 3 June 2025 (read via a verbatim republication). everycrsreport.com
FederalWritten witness testimony, House Committee on Homeland Security, hearing of 22 July 2025. PDF
GovernmentMassachusetts Department of Environmental Protection, Drinking Water Program, "Cybersecurity Advisory for Public Water Suppliers," undated. Source of the TeamViewer, 32-bit Windows 7, shared password and no-firewall details; names no source for them. mass.gov
PressCybersecurity Dive, 9 February 2021, reporting the 8 February 2021 press conference (the operator assumed the morning session was a supervisor's). A paraphrase, not a quotation; not in the sheriff's written release.
GovernmentIdaho National Laboratory, CyOTE program, case study on the Oldsmar incident, online as of 2026. PDF
PressDark Reading, 9 February 2021, reporting Oldsmar Mayor Eric Seidel's remarks at the 8 February 2021 press conference. Cited as evidence of what was said; no transcript or recording was consulted.
Cite this page
BlastWave. “Oldsmar Water Treatment Plant Incident (2021): What Is Verified.” Hackopedia, Volume 2, FILE 005. Last verified 28 September 2026. https://hackopedia.blastwave.com/water/oldsmar-2021/
Revision history
Date
Change
6 Oct 2026
Numbered FILE 005 in Hackopedia Volume 2, in the Water edition.
28 Sep 2026
Final consistency check: every field re-read against its sources and against the other Hackopedia entries that mention Oldsmar. An unmeasured superlative ("the most cited water incident") stays softened to "among the most cited."
26 Sep 2026
Full validation. Confirmed through a February 2021 republication that the advisory's web text then lacked the "cannot be confirmed" clause. Corrected two press citation titles, and withdrew a statement that BlastWave had used the hundred-fold figure; no BlastWave publication had.
25 Sep 2026
Second verification against the federal advisory's current text and three 2021 copies. Corrected three points: the advisory does judge poor password security and an outdated operating system "likely"; its "cannot be confirmed at present date" clause is quoted as current wording, not 2021 wording; and it says the SCADA software alarmed after the operator had corrected the change.
24 Sep 2026
Volume 2 entry built from primary sources and marked Contested. Corrected Volume 1 errors: TeamViewer stated as the vector, the RDP framing, and harm language that went beyond the sheriff's own words.
How Hackopedia verifies an entry
Every figure, date and quotation traces to a court record, sworn testimony, a government or regulator document, the operator's own dated statements, a named researcher's published work, or a dated publication named as such. Where the record says less than the headlines, we print what the record says and mark the rest as reported or undisclosed. Pages are re-verified when new filings, rulings or official statements appear, and every change is logged. Why Hackopedia exists · How to read an entry
