TankWatch hangs on the tank, watches the waterline, and sends a notification when a flapper sticks or a fill valve won't quit — before it becomes a four-figure water bill.
Join the pilot See how it worksNo hub · No subscription · 3×AAA, ~6 months
How it works
A thin bracket slips over the tank wall — the lid still seats. Two stainless probes sit just above the normal waterline inside. The sealed battery box hangs outside, where changing batteries doesn't mean reaching into a toilet tank.
Hold the button, join it to your network from your phone, done. No hub to buy, no cloud account it can't live without — the beeper works even if your internet doesn't.
It wakes for a few milliseconds every 30 seconds, sips the waterline, and goes back to sleep. Twice a day it checks in with battery status. You'll hear from it when something's wrong — and only then.
The five-minute rule
Every flush wets the probes for a minute while the tank refills — that's normal, and TankWatch stays quiet. A running toilet never lets the water drop. Wet for five straight minutes is the tell.
Chirp in the bathroom. Notification on your phone — even if you're out of town. That's the whole product.
Honest hardware
There's no exotic sensor inside. Tank water conducts; air doesn't. Two stainless screws bridge when the water is high, and a microcontroller does the arithmetic. Fewer parts, fewer failures.
| Radio | 2.4 GHz WiFi (joins only to send) |
| Batteries | 3 × AAA alkaline |
| Battery life | ~6 months typical |
| Check interval | Every 30 seconds |
| Alert threshold | 5 minutes continuously wet |
| Local alert | Piezo chirp, ~70 dB |
| Heartbeat | Every 12 h with battery status |
| Fits tank walls | Up to 30 mm, lid stays seated |
| Enclosure | Moisture-rated PETG |
| Subscription | None. Ever. |
Hall bathroom: water high for 5+ minutes.
TankWatch · nowQuestions
Because the expensive failures are the quiet ones — a flapper that seals almost, a fill valve trickling into the overflow tube. TankWatch reads the waterline itself, which can't be fooled by a quiet leak or masked by a loud fan.
No. Each unit joins your home WiFi directly and only powers its radio when it has something to say. One device, one battery set, one job.
The local chirp still works — detection happens on the device, not in a cloud. The notification catches up when your connection returns.
The bracket clears tank walls up to 30 mm — that covers nearly every residential tank — and the lid sits back down over it. If yours is unusual, the pilot is exactly the place to tell us.
Red Zone Enterprises, a data-reconciliation consultancy in the DC corridor whose reputation is built on one promise: the reports will be right. TankWatch is that promise, pointed at your water bill.