Fresh produce keeps making people sick, and the industry cannot tell whether anything it does about it works. Lume closes that gap with continuous fecal-indicator monitoring at the two points where water touches the crop — the irrigation source before harvest, and process water before it contacts product — giving growers, processors, and the brands that stand behind them a shared, auditable record of the water that reaches food.
By mid-July 2026, public health officials had reported more than 8,600 cyclosporiasis cases, a record, against roughly 3,000 to 3,600 in each of the four preceding years. FDA initially attributed a large share to iceberg lettuce supplied to Taco Bell by Taylor Farms, driving a recall across 27 states, then announced the identification was a mistake. Five states have reported 1,644 illnesses among people with that exposure, with 94 hospitalizations.
The parasite reaches produce the same way most produce pathogens do: it is shed in human feces and arrives on the crop through contaminated irrigation water. Cyclospora is the headline, but it is a small share of a much larger problem. Contaminated salad greens alone are associated with an estimated 2.3 million illnesses and $5.2 billion in annual health care costs, and produce-borne pathogens account for roughly a quarter of the estimated 1,300 annual deaths from the most commonly recognized foodborne agents.
The recall machinery is downstream of the real failure. As Timothy Lytton put it in the New York Times this month, growers can switch from canal to well water, and processors can gas lettuce with ozone, and neither can demonstrate that it reduced illness. Surveillance captures only a small fraction of foodborne illness, doctors rarely test for a pathogen that resolves in days, and patients cannot recall what they ate two weeks ago. Of 48 million annual episodes, only a tiny fraction are ever linked to a food category and a smaller fraction to a specific product.
That is an outcome-measurement problem, and no water sensor solves it. What a sensor can fix is the exposure side. If you have a continuous record of what was in the water before and after an intervention, the intervention finally has something to be evaluated against. Grab sampling cannot do this: it is a snapshot on a fixed schedule, structurally blind to the transient events, a storm, an upstream discharge, a failed lift station, that carry the contamination.
Periodic grab samples sent to a lab, with a multi-day turnaround, on a calendar that has no relationship to when contamination actually occurs.
Excursions. Fecal loading in surface irrigation sources is event-driven and short-lived. A weekly sample has a low probability of intersecting the event that matters.
A defensible baseline, detection of the excursion while the water is still in the ditch, and a before-and-after record that makes a capital intervention auditable.
When contaminated produce reaches a consumer, the name in the headline and on the recall notice is rarely the farm. It is the restaurant that served the salad and the retailer whose store brand is on the bag. In the 2026 cyclospora outbreak a national quick-service brand was publicly tied to the illnesses on the strength of an identification the FDA later retracted — the reputational damage lands first and is corrected later, if at all.
Those brands carry the liability and the consumer trust, yet they have no direct visibility into the irrigation and process water that decided whether the crop was safe. Their only instrument today is a supplier audit built on periodic grab samples. Continuous monitoring changes what a brand can require and verify: instead of trusting that a supplier followed a procedure, it can hold a continuous record of the water that actually touched the product — the difference between “we met the audit” and “here is the evidence.”
Bear the outbreak headline and the recall. Continuous supplier-water data turns a food-safety specification from a paper requirement into a measured one.
Own the brand of record on private-label produce, and the recall that follows it. A shared water record de-risks the categories most exposed to fecal contamination.
Where the water is, and where the measurement happens. An auditable record becomes an asset in buyer negotiations, not just a compliance cost.
The Lume measures tryptophan-like fluorescence (TLF), the ultraviolet fluorescence of tryptophan in proteins, at 273 nm excitation and 350 nm emission. In laboratory cultures most of this signal sits inside bacterial cells and tracks microbial activity (Fox et al. 2017). The Lume is calibrated against E. coli culture counts in CFU/100 mL, the unit in which irrigation and recreational water standards are written.
TLF and E. coli rise together where sewage or animal waste is the main source of organic matter, because the same discharge delivers both. Relationships between TLF and E. coli have been reported in groundwater, rivers and an estuary on three continents, and their strength varies by site (Baker et al. 2015; Sorensen et al. 2021; Harrison et al. 2024). Each Lume site is therefore calibrated against culture counts.
TLF is not specific to feces. Non-fecal bacteria and some plant wastes also fluoresce in the tryptophan region (Fox et al. 2017; Baker 2002), and humic material from soil and plant decay absorbs at the excitation wavelength and quenches tryptophan fluorescence (Kothawala et al. 2013; Wang et al. 2015). The Lume corrects for temperature and turbidity with its own channels, and site calibration accounts for the local organic background.
TLF measures fecal and microbial loading in the water. It does not identify a named organism such as cyclospora, which reaches produce through fecally contaminated irrigation water.
Water touches the crop twice, and both contacts are measurable with the same sensor and the same calibration. Because Lume resolves down to drinking water concentrations, the plant can be instrumented on either side of chlorine injection: the intake gives source quality and incoming load, the post-dose line gives the water actually contacting product. Measuring both turns disinfection from an assumed step into a verified one, which is the difference between a dosing record and evidence.
Canal, reservoir, well or surface intake. Event-driven fecal loading from upstream human and animal sources. Continuous TLF establishes a source baseline and flags excursions before the water reaches the field.
Lume in situContamination acquired here travels with the crop. No water sensor observes this stage, which is why the source measurement upstream is the one that carries information.
Plant intake, reconditioned or recycled wash water returning to the flume, final potable rinse, hydrocooling and ice-making supply. Measured pre-dose, post-dose, or both.
Lume in lineControl point 2 carries most of the regulatory weight, and being able to read across the disinfection step is what makes it commercially interesting rather than a compliance box. A plant that can show incoming load, post-dose residual quality, and the effect of a water change has an operating instrument, not just an audit artifact. The value is highest where intake quality varies: plants on their own well or surface source, and plants reconditioning wash water back into the flume, which is increasingly common under water cost and drought pressure.
The measurement question a produce buyer will ask is whether the instrument resolves clean water, because a treated intake and a post-chlorination rinse sit far below the concentrations found in a river. That case is already validated. Lume was tested against 216 paired Compartment Bag Test observations in Rwanda and Kenya, classifying at the ≥10 CFU/100 mL drinking water threshold with 85% balanced accuracy (76% sensitivity, 93% specificity), approaching the reference method’s own inter-method reproducibility ceiling. Detection extends to below 0.1 ppb tryptophan in deionized water.
Two consequences for this application. Chlorinated process water is within range, so the intake can be measured before and after dosing rather than only at the source. And because the instrument performs at drinking-water concentrations, it operates in the range where the post-harvest standard lives — giving continuous assurance that disinfection is holding and an immediate flag when it is not. Lume complements the confirmatory laboratory test that certifies conformity; it does not replace it.
Lume is validated in drinking, recreational, and coastal water; produce is a new application of the same instrument and the same calibration. The right first step is a season of continuous monitoring on a working irrigation source or process-water line, run alongside whatever grab sampling already happens there, so the produce sector builds its own dataset rather than borrowing ours from rivers.
Instrument a source or process-water line for a season. You get an early-warning record of your own water and a defensible baseline; we get a produce-specific validation. Deployment is a short step from the monitoring we already run for utilities and regulators.
Put continuous water data behind your supplier food-safety program. We will stand up a pilot on a supplier’s water and share the record with your food-safety team, so you can see what continuous evidence adds to what your audits already require.
Help define what continuous water data has to prove before it can count in a pre-harvest assessment or an audit. We would rather build to that specification from the start than deliver another dashboard that sits beside the record instead of counting toward it.
The same sensor and calibration cover agricultural and process water. For partners already selling water instrumentation into food and beverage accounts, produce is a natural extension of an existing channel.
Lume provides a continuous, auditable record of microbial loading in the water that touches food, at both points where that water is still controllable, at concentrations from drinking water upward and on either side of disinfection. It does not replace laboratory microbiology, and it does not speciate a parasite. It makes a prevention investment measurable, and measurability is precisely what the fresh produce sector has never had.
This is the same accountability argument Virridy makes in surface water and in carbon, applied to a sector that is under acute public pressure and has no continuous measurement layer of its own.