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Why Do Home Floods Get Found So Late? Eight Real Cases, One Pattern. What Is An "Escape Of Water", And Why Does It Run For Hours Before Anyone Notices? The Sensor Saw The Leak At 11:30 PM. Nobody Saw The Sensor Until Morning. What Real Floods Teach.

Water pooling and splashing on a wooden floor
Home Signal explainer desk15 September 2026

Insurers have a dry name for the most common home disaster in Europe: escape of water. Not storms, not rivers. Water that gets out of a hose, a joint or a pipe inside the house.

Most people picture a burst pipe and a fountain. The real accounts look different. The water gets out quietly, and nobody finds it for hours. Sometimes for weeks.

We read through dozens of public accounts from homeowners, tenants, a fire service log and a home-automation forum. Eight are below. Then we explain how the leak happens, what people wrongly assume, and how a sensor changes the one number that matters.

Insurers have a dry name for the most common home disaster in Europe: escape of water. Not storms, not rivers. Water that gets out of a hose, a joint or a pipe inside the house.

Most people picture a burst pipe and a fountain. The real accounts look different. The water gets out quietly, and nobody finds it for hours. Sometimes for weeks.

We read through dozens of public accounts from homeowners, tenants, a fire service log and a home-automation forum. Eight are below. Then we explain how the leak happens, what people wrongly assume, and how a sensor changes the one number that matters.

Insurers have a dry name for the most common home disaster in Europe: escape of water. Not storms, not rivers. Water that gets out of a hose, a joint or a pipe inside the house.

Most people picture a burst pipe and a fountain. The real accounts look different. The water gets out quietly, and nobody finds it for hours. Sometimes for weeks.

We read through dozens of public accounts from homeowners, tenants, a fire service log and a home-automation forum. Eight are below. Then we explain how the leak happens, what people wrongly assume, and how a sensor changes the one number that matters.

In one sentence

An escape of water is water leaving a pipe, hose, tank or appliance inside the home, and the damage is set far more by how long it runs than by how much comes out at once.

The short version

Eight real cases, and the pattern in them

None of the people in these cases used Shelly products or were paid for their accounts. Each one is quoted from a public post, and every source is linked in full.

A software engineer's personal blog · February 2022

The sensor saw the leak at 11:30 pm. Nobody saw the sensor until 7:30 am.

A joint near the hot-water connection in his garage failed and began spraying hot water. He already had a leak sensor on the floor right next to it. It detected the water and wrote the time into its history.

What it did not do was tell anyone. He had never set up an alert. His wife found the leak the next morning, after hearing odd noises and seeing steam.

The plumber traced it to water pressure running close to 120 psi, more than the water heater could take. The heater and a pressure regulator were replaced. The first thing he did afterwards was set up the alert, with texts, flashing lights and a spoken warning.

“I never set up any alerts to tell me when the sensor detected a leak.”

Read his full write-up

8 hoursbetween the sensor detecting water and a person finding it
MoneySavingExpert forum · user “Cantisque” · January 2024 · UK

A midday leak, a wet carpet downstairs, and a letting agent asking who pays

The washing machine was five and a half years old. At midday the owner found it had stopped working and was leaking. They switched it off and mopped up.

The flat below had already taken the water: a wet carpet and a damp wall. The letting agency raised the question of liability. The poster photographed everything as it happened, to send to a relative for advice.

Read the original thread

2 flatsaffected by one ageing washing machine
Mumsnet · user “ohflood” · January 2023 · UK

A leak everyone knew about, and a tap left running for four and a half hours

There was a known drip from a hose in the flat. It was caught in a container, and the repair was on the to-do list. Then someone left the tap running and went out.

About four and a half hours later the water had reached the flat below: wet walls, wet carpet, ruined wallpaper. The owner's insurance excess alone was 600 to 850 pounds, so they planned to pay the neighbour directly. A reply in the thread pointed out the harder problem. Because the leak was known, the neighbour could claim negligence.

“I have every intention of covering all the costs.”

Read the original thread

£600–850insurance excess, before a penny of repairs
Mumsnet · user “Littlecaf” and replies · March 2016 · UK

The drying took longer than the leak. For one family, about six months.

A burst pipe saturated a kitchen and the rooms beside it. The kitchen was marked for replacement, the carpets came out and most of the furniture was written off. The drying firm estimated 7 to 10 days before the kitchen could even be removed.

The replies told the rest. One household had floors coming up and walls hacked off. Another spent around six months in a hotel and then a rental before going home.

Read the original thread

~6 monthsout of the home, in one reply

Four more, in brief

SourceWhat happenedThe number
MoneySavingExpert, “bluegoldie”, Aug 2024A washing machine leak lifts half the hallway laminate and a quarter of the kitchen's. The insurer will replace only the damaged boards.£650 excess
MoneySavingExpert, “spudgun00”, May 2018A failed shower seal leaks for weeks. The neighbour comes back from holiday to brown ceiling stains and a cracked beam.~£1,000
Buckinghamshire Fire & Rescue, Dec 2024A crew is called at 9:25 pm to a washing machine leak flooding a second flat. They isolate water and electricity.2 flats
Home-automation forum, Apr 2025A phone alert arrives during the grocery shop. A puddle at the water heater is caught while still small.minutes

Read the eight together and the water is never the surprise. The surprise is always the clock.

Where the water actually gets out

Plumbers and loss adjusters give the same short list. The cases above fit it exactly.

1

Appliance hoses

Rubber under mains pressure, pushed against a wall. A washing machine or dishwasher inlet hose is live whenever the tap behind it is open, even with the machine switched off. A clip that loosens by a millimetre lets go the next time pressure spikes.

2

Joints and seals under sinks and baths

Slow, hidden and patient. A trap, a flexible connector or a silicone seal weeps into a cupboard base or a ceiling void. Nothing shows until the chipboard swells or a stain appears downstairs.

3

The water heater

Heat, pressure and age in one box. The first case above was a joint failing at close to 120 psi. Heaters often live in garages, lofts and cupboards where nobody walks past.

Four things people believe that the cases disprove

What people think"A drip tray will catch it."

Trays under machines are cheap and feel responsible.

What the cases showA tray holds about a litre.

A split inlet hose at mains pressure can release ten litres a minute or more. The tray is full in seconds.

What people think"I would hear it."

A burst pipe sounds dramatic.

What the cases showMost leaks are silent, and most happen when nobody is home.

In three of the cases, people were out or asleep. In the fourth, a known drip became a flood while the owner was away.

What people think"Insurance covers it, so it is not my problem."

Escape of water is covered on most policies.

What the cases showThe excess, the matching floor and the months are yours.

Excesses of 600 to 850 pounds, repairs that leave "a patchwork quilt" of flooring, and one family out of their home for about six months.

What people think"Having a sensor is enough."

A sensor on the floor feels like protection.

What the cases showA sensor that nobody hears is a diary.

The first case had one. It recorded the exact minute the leak began, and nobody knew for eight hours.

Work it out

How much water gets out before someone notices?

5,400 Lwater out before anyone knew
36full bathtubs, at 150 litres each
10 Lwith a phone alert in the first minute

Rates are deliberately low. A fully burst hose at mains pressure can deliver several times the 10 litres a minute used here. A drip of one drop a second is about 4 litres a day. Most of the water does not pool. It runs under the units and through the floor, which is how it reaches the flat below.

How a leak sensor works

The idea is older than smart homes and very simple. Two metal contacts sit a fraction of a millimetre above the floor. Tap water carries enough dissolved minerals to conduct electricity, so when water bridges the contacts, a tiny current flows and the sensor knows it is wet.

What changed is what happens next. A modern sensor does three things at once. It sounds in the room, for whoever is home. It sends a message to your phone over your home network, for when nobody is. And it can tell a shut-off valve to close, so the water stops even if you are an hour away.

A floor sensor

Watches one spot

Sits flat under a sink or beside a boiler. Battery powered, so it goes where there is no socket.

A sensing cable

Watches a whole line

A cable that detects water anywhere along its length. It runs behind a washing machine or along a pipe, where a single puck would miss the drip two metres away.

A humidity sensor

Watches for the slow leak

A seal leaking into a wall raises the humidity in that cupboard for weeks before anything reaches the floor. The sensor draws that rising line.

What none of them do

Stop the water on their own

A sensor tells. A motorised valve on the main supply stops. That valve usually sits after the stopcock and is fitted by a plumber.

The lesson from the first case is the whole point. Whatever you install, test that the alert reaches your phone. Pour a glass of water on it and wait for the buzz.

What covering the three failure points looks like

The kit below is one way to do it, from Shelly, the smart-home maker behind this sponsored explainer. A floor sensor for the sink cupboard, two sensing cables for the hoses and the heater, and a humidity sensor for the wall that gets damp first.

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.

If you want to act on this

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 readers ask

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.
Sponsored content. This article is sponsored content published on behalf of Shelly Europe. The publisher earns from purchases made through the links on it. Products were supplied by the manufacturer. Prices are from the manufacturer's store and were correct at the time of writing. Nothing here is legal, insurance or electrical advice.