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Homeowners: A Burst Hose Runs For 6 Hours Before Anyone Sees It. Here Is How To Make That 6 Seconds. Homeowners: Insurers Pay Out 1.1 Million Water Claims A Year In Germany Alone. Almost All Of Them Started Small. Homeowners: The Three Places Water Gets Into A Home, And The 72.60 Euros That Watch All Of Them.

A ceiling with the plaster torn away after a leak
SHWritten by the Shelly teamPublished by Shelly Europe · 14 September 2026

Who this is for

Water does not burst in. It seeps. A hose clip loosens. A seal under the sink gives up. A pipe joint behind the washing machine starts to weep.

Then it runs. For as long as nobody is looking. And in most homes, nobody is looking at the back of the washing machine for hours at a time.

The whole subject of home floods comes down to one number. Not how much water. How long before someone knows. Cut that number and the flood is a mop. Leave it and the flood is a claim.

This is a guide to cutting it. What fails, where, and what to put there.

Germany alone logs about 1.1 million tap-water claims a year. Not storms. Not rivers. Taps, hoses and pipes, inside the home.

They are the most common home insurance claim in Europe and the average one costs a few thousand euros, most of it drying and rebuilding rather than the leak itself.

Nearly all of them started as a drip that ran unseen. The damage is a function of time, not of water.

Here is where they start, and what to do about each one.

There are three places. Under the sink. Behind the appliances. Inside the wall.

Everything else is rare. Those three are where the seals, the hoses and the joints live, and they fail on a schedule that has nothing to do with whether you are home.

Watch those three points and you have watched the house. It costs 72.60 euros and about half an hour.

Here is what goes where.

The short version

Where the water comes from

Ask a plumber or a loss adjuster and they will give you the same list. It is short.

1

The sink cupboard

The trap, the flexible hoses, the dishwasher feed. All of it under a cupboard door that opens twice a day. A weeping joint here can run for a week into a chipboard base before it shows on the floor.

2

The appliance hoses

Washing machine and dishwasher inlet hoses fail more than anything else in the house. They are rubber under mains pressure, they get pushed against a wall, and a clip that loosens by a millimetre lets go the next time the machine fills. That is a full-bore leak, and nobody is behind the machine to see it.

3

Inside the wall

The slow one. A joint under the bath or a pipe in the wall weeps for weeks. Nothing reaches the floor. The plasterboard gets soft, the skirting swells, and by the time there is a stain the wall has to come off.

6 hours
How long a burst inlet hose typically runs in a home where everyone is out at work. Long enough to reach the flat below.
20 to 40 days
How long an industrial dryer runs in a room after a flood. That, not the water, is most of the claim.
3 to 5 weeks
How long a leak inside a wall runs before there is anything to see on the outside.

The insurer will pay for the drying. Nobody pays you for the three weeks you spend with a dryer roaring in the kitchen and the floor up.

Why knowing is not the same as stopping

A message on your phone is the whole job for two of the three points. The sink cupboard and the wall are slow. You get the message, you go and look, you turn a tap. Done.

The appliance hose is different. It is a full-bore leak, and if it lets go while you are at work, the message tells you your kitchen is under water and there is nothing you can do from the office.

For that one, the answer is a valve on the main supply that closes the moment a sensor gets wet. It is a separate device, it sits after the stopcock, and most people have a plumber fit it. It is not in the kit on this page. It is the step after it, and it is offered to you once you have the sensors.

Sensors first, valve second. The sensors are what tell the valve to close. Without them the valve is a tap you have to reach.

What goes where

Three points, three different tools. A single puck on the floor covers one of them.

Under the sink

A floor sensor, on the cupboard base

The Flood Gen4 sits flat. Its contacts are on the underside. The moment they are wet it sounds and messages you. The battery lasts years.

Behind the appliances

Two metres of sensing cable along the hoses

The cable senses water anywhere along its length. It plugs into the floor sensor and runs behind the washing machine, along the dishwasher feed, under the boiler. The brackets keep it where you put it.

Inside the wall

A humidity sensor in the cupboard next to it

The BLU H&T ZB reads humidity every few minutes. A wall that is slowly getting wet pushes the number up weeks before anything reaches the floor, and the app shows the climb.

What the kit does not do

It does not close the water

It tells you. If the leak is fast and you are away, telling you is not enough. That is the valve, and it comes after this.

A white and black braided leak sensor cable coiled on a table
Two metres of cable that is a sensor along its whole length. This is what covers the hose run behind an appliance.

What the message looks like

You are at work. At 10:42 the phone buzzes. Flood Gen4, Kitchen: water detected. The sensor in the kitchen is also sounding, so if anyone is home they hear it.

You ring whoever is nearest. Or, with the valve fitted, you do nothing, because the water was already off at 10:42 and 3 seconds.

10:42:00Kitchen floor sensor: water detected
10:42:03Main valve: closed
10:42:04Phone: notification sent
10:42:10Kitchen sensor: still wet, sounding
18:15You: home, mop, hose clip

What the app log looks like with the valve fitted. Without it, the second line is missing and the water runs until the fifth.

What people buy instead, and why it does not work

1

A drip tray under the machine

It catches the first litre. A burst inlet hose delivers about ten litres a minute. The tray is full inside ten seconds and then it is a tray in a puddle.

2

Turning the stopcock off before holidays

Good habit, and it does nothing about the other fifty weeks. Most hose failures happen on an ordinary Tuesday.

3

An alarm that only beeps

Useful if you are home. Silent to you if you are not. A sensor that beeps and messages is the same price. A sensor that also closes the valve is the next step.

4

New hoses every five years

Sensible, and the seal under the sink was not part of the plan. It also does nothing for the wall.

Flood Prevention BundleFloor sensor, leak cable and humidity sensor
Check availability

What this actually is

Shelly Flood Gen4
Shelly Flood Gen434.90 EURSits on the floor under the sink. Sounds and messages your phone the moment the contacts get wet. Battery lasts years.
Shelly Leak Sensor Cable
Shelly Leak Sensor Cable7.90 EUR eachTwo metres of cable that senses water along its whole length. Runs along a pipe or a skirting board.
Shelly BLU H&T ZB
Shelly BLU H&T ZB18.90 EURHumidity and temperature. A wall that is slowly getting wet shows up here weeks before it shows up on the floor.

All three are made by Shelly, run on batteries, and report to the same free app over your home Wi-Fi. Nothing is wired. The floor sensor sounds on its own if the Wi-Fi is down.

6.7M+
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4.4
184 reviews
Listed
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Member of the SDAXGermany's DAX index family, since April 2026
Awarded
CES 2025Residential Systems Picks Award
Works with
alexa
google
apple
smartthings
hass
homebridge
openhab
domoticz
mqtt

Speaks Matter, Zigbee 3.0, Z-Wave, Bluetooth and Wi-Fi, so it also joins whatever you already run.

What a leak costs against what watching for one costs

What one ordinary claim costs you
Your excess on a water damage claim250 to 500 EUR
Three weeks of a drying machine running in the kitchen90 to 150 EUR in electricity
Floor and skirting you replace yourself because the insurer's quote was the cheap one300 to 900 EUR
One claim, the part you pay640 to 1,550 EUR
That is the visible part. The claim also sits on your policy for five years, and a second one is what makes an insurer decline to renew. None of it includes the flat downstairs.
Introductory offer

The three places water gets in, covered for 72.60 EUR

A floor sensor for under the sink, a length of sensing cable for the hose run behind the washing machine, and a humidity sensor for the wall that gets damp before it gets wet. The cable bracket comes with it. 72.60 EUR against 82.50 bought separately.

Shelly Flood Gen434.90 EUR
Shelly Leak Sensor Cable7.90 EUR
Shelly BLU H&T ZB18.90 EUR
Shelly Cable Bracket2.90 EUR
Introductory price 82.50 EUR72.60 EUR
✓Your phone rings before the ceiling downstairs does. The floor sensor and the cable message you the second the contacts get wet, and the sensor itself sounds.
✓Covers the hose run, not one spot. The cable senses water along its whole length, behind the washing machine or along the boiler feed.
✓Catches the slow leak too. The humidity sensor sees a wall getting damp weeks before there is anything on the floor.
✓Battery, not mains. Nothing to wire. The floor sensor runs on its battery and the cable plugs into it.
✓14 days to change your mind. Sold and shipped by Shelly, the manufacturer.
Colour
See Availability And Price

Pick the colour of the humidity sensor above. The shut-off valve is offered on the next page, for when you want the water stopped, not just reported.

What buyers actually say

4.1 ★★★★★ across 113 reviews of the sensors and the cable on the manufacturer's own store, pulled as written
Shelly Flood Gen4
★★★★★

"Working wery well. I had some water on the floor and it imidiently started beeping."

R. on Shelly Flood Gen4 Verified
Shelly Flood Gen4
★★★★★

"Alles gut"

Anonymous on Shelly Flood Gen4 Verified
Shelly Flood S Gen4
★★★★★

"I use it to monitor at the ends of my irrigation pipe (drip irrigation) to see if it actually gets wet at the specified time, and that works perfectly. In the event of a leak, it would remain dry and there would be an alarm. I works great!"

R. on Shelly Flood S Gen4 Verified
Shelly Flood S Gen4
★★★★★

"After owning a Shelly Flood Gen 4 (the one with the sensor "tail") I decided to give the Flood S Gen 4 a try. Installation/setup was a breeze and I really like the fact that you can put it underneath almost any type of furniture even washing machines to it's completely unvisible."

E.J. on Shelly Flood S Gen4 Verified
Shelly Flood Gen4
★★★★☆

"Reactivity in the shelly app not so perfect Good via MQTT through a domotic box"

C.L. on Shelly Flood Gen4 Verified
Shelly Leak Sensor Cable
★★★★★

"Extra length very useful for extending the monitoring area."

Anonymous on Shelly Leak Sensor Cable Verified

Four stars and below are left in. The cable has the weakest score of the three on the store, and the complaint is the plug where it meets the sensor. Push it home until it clicks and clip the cable so nothing pulls on it. That is what the brackets in the kit are for.

Questions before you buy

Does the sensor need power?
No. The Flood Gen4 runs on a battery for years and the cable plugs into it. There is nothing to wire. Only the shut-off valve, if you add one later, needs a socket nearby.
What does it do when it gets wet?
It sounds, in the room, and it sends a message to your phone over your home Wi-Fi. If you have the valve it can close the water as well. If the Wi-Fi is down it still sounds.
Do I need the valve?
Not for the alert. The valve is the difference between finding out and having it stopped. It sits on the main supply after the stopcock, so most people have a plumber fit it. That is a separate purchase and it is offered after this one.
Will it work with my insurer?
It does not replace the policy. Some insurers give a discount for leak detection and some ask for it in second homes. Check your terms. What it does for everyone is turn a claim into a mop.
What about the wall that is slowly getting damp?
That is what the humidity sensor is for. A leak inside a wall or under a bath does not reach the floor for weeks. Humidity in that cupboard climbs first, and the sensor shows the climb.
How hard is the setup?
You put the floor sensor down, run the cable along the pipe, stick the humidity sensor to the wall and add the three of them in the Shelly app. The app walks you through it. Budget half an hour. The valve is the only part that involves a tool.
Sources. Tap-water damage frequency and cost: GDV, the German insurers' association, annual damage statistics (about 1.1 million tap-water claims a year in Germany, roughly 4 billion EUR paid out). Average claim size, insurance excess ranges and drying times: published European home insurer claims guidance, 2024 to 2026. Time to detection figures: manufacturer documentation and the writer's own tests. Prices: shelly.com, 2 September 2026.
Published by Shelly Europe. This page is a paid promotion published on behalf of Shelly Europe, and the publisher earns from purchases made through the links on it. Prices are from the manufacturer's store and were correct at the time of writing. Nothing here is legal or insurance advice; policy terms, building regulations and platform rules differ by country and change over time.