Your toilet can now analyse your urine. For most people it measures thirst.

The idea has been circling research labs for years: the one piece of health data you produce every single day, several times, and flush away without looking. Urine is cheap, continuous and nobody has to remember to take a reading.

In October 2025 it stopped being a lab idea. Withings began selling U-Scan, a device that sits inside your toilet bowl and analyses your urine as you go, in Europe and the United States. It works. The question is whether you have any use for what it tells you.

What it is and what it costs

U-Scan is a pebble-shaped reader that clips into the bowl, with a replaceable cartridge holding the test chemistry. It identifies you by your urine stream rather than asking you to log in, runs the sample against the cartridge, and sends results to a phone app.

Two versions launched. Nutrio reads hydration, specific gravity, pH, vitamin C and ketones. Calci is aimed at people prone to kidney stones.

The pricing is where you should pay attention, because it is a razor-and-blades model. The Proactive Plan is 379.95 dollars and covers two to four analyses a week with one cartridge. The Intensive Plan is 449.96 dollars for five to seven analyses a week with two cartridges. Then the cartridges run out, and replacements start at 99.95 dollars, shipped every one to three months.

Run the Intensive plan for a year and you are looking at the hardware plus roughly four to twelve cartridge renewals. This is a subscription with a device attached, which is the same structure we found when we looked at glucose monitors sold to people without diabetes.

The science underneath is real

This is not a gadget invented by a marketing department. The foundational work was published in Nature Biomedical Engineering in 2020: a mountable toilet system for personalised health monitoring through the analysis of excreta, from a Stanford group. It used test strips, computer vision and even fingerprint and anal-print recognition to identify users, and demonstrated the principle that a toilet could do continuous, passive screening without anyone changing their behaviour.

Passive monitoring is the genuinely attractive part. Every other health tracker fails eventually because people stop wearing it, stop charging it or stop caring. A toilet does not have an adherence problem.

Research reviews since then have mapped the wider field of smart sanitary hardware, and the long-term ambition is serious: detecting urinary tract infections, tracking kidney function, spotting the metabolic signatures of disease early. That is a legitimate research programme.

What you actually get today

Hydration status, mostly.

> Most healthy people don't need a urine tracker.

That is the conclusion a reviewer reached after living with one, and it is hard to argue with. The markers in the consumer cartridges are real measurements, but for a healthy adult they mostly tell you things you either already know or cannot act on. You are dehydrated: drink water. Your pH shifted: this reflects what you ate. Ketones present: you skipped carbohydrates.

The kidney stone version has a clearer case. If you form stones, fluid intake and urine chemistry genuinely matter, and monitoring can be part of prevention. That is a defined group with a defined question, which is exactly the structure that makes any test worth running.

For everyone else, you are paying a recurring fee to be told to drink more water.

The part nobody is discussing

There is a privacy dimension here that has had almost no coverage. This is a device that identifies individual household members automatically and builds a continuous biochemical record of each of them, held by a company, tied to an account.

Urine reveals pregnancy, drug use, kidney disease and dietary patterns. We are not suggesting anything improper is happening at Withings. We are pointing out that a permanent, automatic, per-person biochemical log in the bathroom is a genuinely new category of personal data, and the norms for it do not exist yet. Worth reading the data policy before the hardware goes in.

Our take

The engineering is impressive and the research behind it is sound. Passive monitoring that requires nothing from the user solves a problem every wearable has.

But for a healthy adult the readings available today are hydration and diet echoes, at 380 to 450 dollars up front plus roughly 100 dollars a cartridge, indefinitely. That is a lot of money to confirm you should drink more water.

If you form kidney stones, the Calci version is worth discussing with your doctor, and there is a real question it answers. If you are curious rather than symptomatic, wait. The interesting version of this product is the one that detects a urinary tract infection before you feel it, and that one is not on sale yet.