Oxygenator v. Tennant: $20.3M Judgment Stayed Pending Appeal in ec-H2O Patent Dispute
Oxygenator Water Technologies secured a judgment against Tennant Company over three reissue patents covering electrochemical water activation technology embedded in Tennant’s ec-H2O floor scrubbers. After nearly six years of litigation in the Minnesota District Court, Tennant posted a $20,296,044.84 supersedeas bond to stay enforcement while it pursues an appeal.
Six-Year Minnesota Patent Battle Over Electrochemical Floor-Cleaning Technology
Oxygenator Water Technologies, Inc. filed this infringement action in the District of Minnesota on January 27, 2020, asserting three reissue patents — USRE047092E, USRE045415E, and USRE047665E — against Tennant Company, the Minneapolis-headquartered commercial cleaning equipment manufacturer. The patents cover electrochemical water activation technology, and the accused products include Tennant’s cylindrical electrode product and the full range of ec-H2O-equipped floor scrubbers, spanning more than 20 distinct models from the T3 to the M20.
After nearly six years of litigation, the court entered judgment in favor of Oxygenator on September 17, 2025. Tennant responded by filing an unopposed motion to stay enforcement of that judgment, which the court granted on December 29, 2025. Tennant’s $20,296,044.84 supersedeas bond was approved, and all proceedings to enforce or execute upon the judgment — including any additional fee and cost awards — are stayed pending the outcome of Tennant’s appeal. The case is formally closed at the district court level, but the substantive dispute has migrated to the appellate forum.
A duration of 2,163 days is notably extended even by complex patent litigation standards, suggesting the parties likely contested claim construction, validity, and damages through multiple rounds. The supersedeas bond amount — slightly above $20.3M — provides a concrete floor for the damages award, though the final total exposure could be higher once fees and costs are resolved. The public docket does not disclose the royalty base, rate, or damages methodology, and the specific grounds Tennant intends to raise on appeal remain unknown from publicly available records.
Filing to Case Stayed in 2163 days
5 years 11 months — substantially longer than the median U.S. patent case
Judgment entered for plaintiff; enforcement stayed on $20.3M bond pending appeal
What a supersedeas bond stay means in practice
A supersedeas bond allows a judgment debtor to delay payment and enforcement while an appeal is pending. By posting $20,296,044.84 — typically set at or near the full judgment amount plus interest — Tennant secured a court order preventing Oxygenator from executing on the judgment. The stay remains in effect until the appellate court resolves Tennant’s appeal or the district court orders otherwise. The judgment creditor’s risk is mitigated by the bond.
Enforcement deferredOxygenator holds a judgment but must wait for collection
Oxygenator secured a favorable judgment on September 17, 2025 — a significant litigation win after nearly six years. However, the stay of enforcement means no funds are immediately recoverable. The supersedeas bond provides security that the award will be collectible if the judgment is upheld on appeal. Oxygenator’s patent portfolio covering ec-H2O technology remains in force, and the judgment strengthens its negotiating position against other potential infringers in the commercial cleaning sector.
Judgment secured, collection pendingTennant preserves appeal rights while protecting its balance sheet
Tennant successfully obtained an unopposed stay, preserving its right to challenge the judgment on appeal without immediate cash outflow. Posting a bond of over $20.3M is a significant commitment, but it avoids forced collection during appellate proceedings. The appeal gives Tennant a further opportunity to challenge the validity of the asserted reissue patents or the damages calculation. The outcome of the appeal will be determinative for Tennant’s long-term liability exposure on its ec-H2O product line.
Appeal in progressReissue patent enforcement risk for the cleaning equipment sector
This case signals that reissue patents covering electrochemical water activation — a technology increasingly embedded in commercial floor care equipment — carry real enforcement teeth. The $20M+ judgment against a major OEM suggests that infringing an established reissue patent on core cleaning chemistry can result in substantial damages exposure. Competitors deploying similar cylindrical electrode or electrochemical water treatment systems should treat this judgment as a material FTO signal, regardless of the appeal outcome.
High damages exposure confirmedFull party and counsel information
| Role | Name | Type | Detail |
|---|---|---|---|
| Plaintiff | Oxygenator Water Technologies, Inc. | Company | Electrochemical water technology IP licensor — holder of USRE047092E, USRE045415E, and USRE047665ESearch in Eureka ↗ |
| Defendant | Tennant Company | Company | Tennant Company — global commercial floor cleaning equipment manufacturer, Minneapolis, MNSearch in Eureka ↗ |
| Plaintiff counsel | Aaron W. Pederson | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Christopher Ross Johnson | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Hannah Mosby O’Brien | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | J. Derek Vandenburgh | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Nathan Louwagie | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Philip P. Caspers | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Richard Willets Ely | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff counsel | Todd Stephen Werner | Attorney | Counsel for Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Avantech Law LLP | Law Firm | Representing Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Carlson, Caspers, Vandenburgh & Lindquist PA | Law Firm | Representing Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Plaintiff law firm | Eckland & Blando LLP | Law Firm | Representing Oxygenator Water Technologies, Inc.Search in Eureka ↗ |
| Defendant counsel | Adam R. Steinert | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Bob Oakes | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Brianna Lee Chamberlin Patterson | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Cara S. Donels | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Douglas E. McCann | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Jon Bell | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Joseph B. Warden | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Kurt J. Niederluecke | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Lora Mitchell Friedemann | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Madison Murhammer Colon | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Martina (Tyreus) Hufnal | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Nitika Gupta | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Robert Scott Johnson | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Ryan Petty | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Taylor Reeves | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Thomas M. Patton | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant counsel | Timothy M O’Shea | Attorney | Counsel for Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Cooley LLP | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Fish & Richardson – Bob Oakes | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Fish & Richardson – Doug McCann | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Fish & Richardson – Martina Hufnal | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Fish & Richardson PC | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Fredrikson & Byron PA | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Fredrikson & Byron, PA | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Defendant law firm | Office of the Minnesota Attorney General | Law Firm | Representing Tennant CompanySearch in Eureka ↗ |
| Presiding judge | Judge N/A | Judge | Minnesota District CourtSearch in Eureka ↗ |
Official order — verbatim text
The court’s December 29, 2025 order does not adjudicate the merits but confirms the damages judgment of September 17, 2025 is sufficiently certain to support a $20,296,044.84 supersedeas bond. The unopposed nature of the stay motion suggests Oxygenator did not contest the bond amount or the stay mechanics — consistent with a negotiated enforcement arrangement. The explicit carve-in of ‘any additional judgement that may be entered for fees and costs’ indicates further monetary exposure for Tennant remains unresolved, meaning the $20.3M figure likely represents a damages floor rather than a ceiling.
USRE047092E, USRE045415E, USRE047665E — Electrochemical Water Activation Technology
The three asserted patents — USRE047092E, USRE045415E, and USRE047665E — are all reissued U.S. patents, meaning each originated as a granted patent that was subsequently surrendered and reissued with corrected or broadened claims. Their respective corrected application numbers (15/085741, 13/247241, and 14/601340) span a multi-year filing window, consistent with a strategy of building a layered patent family around a core electrochemical water activation technology. The technology enables commercial cleaning equipment to generate oxidative cleaning solutions from water and electrolytes using electrochemical cells — eliminating the need for conventional chemical detergents.
Tennant’s ec-H2O platform, accused across more than 20 floor scrubber models, represents one of the most commercially successful deployments of on-board electrochemical water treatment in the commercial cleaning sector. Oxygenator’s decision to assert reissue patents — rather than original grants — suggests a deliberate strategy to align claim scope with the commercially dominant product architecture that emerged after the original filings. For competitors in the industrial and commercial cleaning equipment space deploying similar electrolyzed water or electrochemical dosing systems, these three reissue patents represent active, court-validated IP that has now survived a full district court trial.
Should your product team run an FTO against USRE047092E, USRE045415E, and USRE047665E?
Any manufacturer or developer integrating electrochemical water activation, electrolyzed water generation, or cylindrical electrode-based cleaning systems into commercial or industrial floor care equipment should treat this patent family as a live FTO concern. The district court judgment against Tennant — across 20+ SKUs — confirms that these reissue patents have claim scope broad enough to cover a major OEM’s flagship product line. The risk is not limited to direct competitors of Tennant; any product generating oxidative cleaning solutions via electrochemical cells at point-of-use could fall within the asserted claim space.
PatSnap Eureka’s FTO Search Agent can map the independent and dependent claims of USRE047092E, USRE045415E, and USRE047665E against your product architecture, flag structural or functional overlaps, and identify prior art that could support design-around or IPR strategies. With Tennant’s appeal in progress, the claim construction applied by the district court may shift — Eureka monitors appellate dockets and updates FTO risk scores in real time as case law develops.
Run a freedom-to-operate analysis on USRE047092E to assess your product’s exposure
Run FTO in Eureka →Similar Electrochemical Water Technology Patent Cases in U.S. District Courts
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What this case signals for the electrochemical cleaning technology IP landscape
A $20M+ judgment and a six-year litigation timeline indicate that electrochemical water technology IP is being enforced aggressively — and courts are responsive.
Reissue patents in this space carry amplified enforcement risk
All three asserted patents are reissues — meaning the claims were broadened or corrected post-grant. Reissue patents often have broader claim scope than their originals, which can capture product iterations a patentee did not initially anticipate. Any company deploying electrochemical or electrolyzed water technology in cleaning equipment should audit against the reissue claim scope, not just the original.
A $20M+ judgment signals damages methodologies are working for plaintiffs
The supersedeas bond floor of $20,296,044.84 confirms a substantial damages award was entered. For a specialized IP licensor suing a major OEM across 20+ product models, this outcome suggests that royalty base and apportionment arguments were litigated and resolved in the patent holder’s favour. R&D teams and in-house counsel should model realistic damages exposure before product launch, not post-filing.
Oxygenator v Tennant — key questions answered
Oxygenator asserted three reissue patents: USRE047092E (corrected application 15/085741), USRE045415E (corrected application 13/247241), and USRE047665E (corrected application 14/601340). All three cover electrochemical water activation technology deployed in Tennant’s ec-H2O floor scrubber product line.
The Minnesota District Court entered judgment in favor of Oxygenator on September 17, 2025. Tennant subsequently posted a $20,296,044.84 supersedeas bond and obtained a court-ordered stay of enforcement pending its appeal. The case is closed at the district court level; the appellate proceeding will determine final resolution.
A supersedeas bond is a form of security posted by a judgment debtor to stay enforcement of a money judgment while pursuing an appeal. By posting $20,296,044.84 — approximating the damages judgment — Tennant prevented Oxygenator from immediately executing on the award. The bond guarantees that funds will be available to satisfy the judgment if the appeal fails.
The accused products include Tennant’s cylindrical electrode product and over 20 ec-H2O-equipped floor scrubber models, including the T3, T5, T7, T12, T15, T16, T17, T20, M17, M20, M3, A3, A5, 5680, 5700, 5700XP, 7100, 7300, 8300, and Speed Scrub series machines.
Yes. The district court judgment confirms the patents survived Tennant’s invalidity and non-infringement defenses through trial. However, Tennant’s appeal may challenge claim validity or construction, so final enforceability determination remains pending. Third parties should note that reissue patents with confirmed district court judgments carry heightened enforcement risk until and unless reversed on appeal.
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