Water damage in an empty house, or how to multiply a bill by ten

A weeping flexible connector passes roughly one litre an hour. Twenty-four litres a day. Almost nothing: in an occupied bathroom you hear it, you see the mark, you tighten the fitting and that is the end of it.

Multiply by forty-two days — the average interval between visits to a house looked after "by the neighbour" — and you have a thousand litres under a floor screed. At that point it is no longer a leak. It is a project.

I. What actually happens over six weeks

Water does not sit still. It travels, downwards and sideways, following whatever routes the building offers.

First days: the screed absorbs. Nothing is visible, including to anyone visiting. The tiles feel dry.

Second week: water reaches the insulation beneath the screed. Waterlogged polystyrene loses most of its thermal performance and never dries out in a closed house. On underfloor heating, efficiency starts to fall with nobody the wiser.

Third week: the partitions. Plasterboard wicks up twenty to sixty centimetres depending on the lining. Skirtings swell. Floating engineered flooring lifts and cups.

After a month: the smell. That is often the first human signal — the neighbour who comes in for the post and finds it "a bit musty". By then mould is established in the linings, and the treatment is no longer drying but stripping out.

II. The six starting points, by frequency

Across the houses we take into management, the origin of the claim breaks down fairly consistently.

1. Flexible connectors — the braided stainless hoses under basins and behind WCs. Real service life: five to seven years. Almost nobody replaces them before failure.
2. Washing machine and dishwasher — supply hose under standing pressure, door seal, a solenoid valve stuck open.
3. Hot water cylinder — tank corrosion, a scaled safety group that no longer reseats. A holed cylinder releases 200 litres at once, then keeps refilling.
4. Roof and terrace waterproofing — cracked upstands, outlets blocked with pine needles. Typical of the flat roofs on contemporary villas at Pyla.
5. Buried irrigation — a pipe split by frost waters the subsoil for a whole spring, and the excess consumption only shows on the annual bill.
6. Swimming pool — a leak at the main drain or in the plant room, emptying the pool and saturating the ground around the foundations.

III. Insurance: what the policy actually says

This is where owners discover, at the worst possible moment, a clause they never read.

Most household policies contain, for second homes, an unoccupancy clause. It typically provides that beyond a continuous period of absence — often thirty, sixty or ninety days depending on the policy — certain cover is reduced, made conditional on precautions, or suspended.

The precautions required look almost identical from one insurer to the next: water shut off at the main, systems drained during frost, heating maintained on frost protection, and periodic visits capable of proof.

The important word is capable of proof. In a dispute, the insurer will not ask whether someone was calling in: it will ask you to demonstrate it. A dated visit report with photographs is worth infinitely more than a statement written after the event. That is one reason we time-stamp and archive every visit — not out of administrative habit, but because that document becomes evidence the day there is a claim.

The subject is worth going into: see Insurance and unoccupancy, the clause nobody reads.

IV. Detect early, or not at all

There is no single solution. There is a chain, and it is worth what its weakest link is worth.

Level zero: the valve closed. A house whose mains supply is shut off between stays cannot flood. It is free, it is absolute, and it is incompatible with a water heater left in service or with occasional letting.

First stage: contact sensors. A pad on the floor under each water point, at five or ten euros each. It detects water once it reaches the floor — so late, but well before six weeks.

Second stage: the motorised valve. An actuator on the main supply, driven by the sensors, which shuts the water off automatically. It is the only device that turns an alert into an action when nobody is there.

Third stage: flow analysis. A smart meter that learns the house's consumption profile and flags the anomaly — a continuous overnight flow, for instance — before water ever reaches the floor.

We set out the real limits of each of these, including what they cannot do, in Detecting a leak from six hundred kilometres away.

V. The human factor is still decisive

An alert is only useful if somebody can respond to it.

I labour the point because it is the blind spot of almost every device sold to absent owners. The sensor sends a notification. The owner is in Brussels, in a meeting, and sees it two hours later. He calls a plumber he does not know, who cannot get in, and who will not come.

A complete chain means: detection, notification, somebody with the key, the mandate and the number of the plumber who knows the house, and a written record of what was done. The first three links are sold in shops. The fourth cannot be bought; it has to be organised.