It has started raining for the first time in months and your apartment in Athens is empty. From three countries away you cannot do anything, but you can hope that the balcony drain of your terrace has not been clogged by the summer leaves and the dirt that has accumulated there. And if by mistake it has been clogged, then the water will flow under the door of the balcony.

That is how most autumn floods of empty Greek apartments are caused. Not by the size of the storm, but by a small blockage of a drain that nobody knew was there in the first place.

It rains for the first time in months and your Athens apartment starts flooding. This is how most flooding of empty Greek properties happens: not because of huge amounts of rain but as a result of one small blockage. In most cases this happens on the first heavy rains of October, when the owner of the property is abroad. Home Watch Athens clears all balcony and terrace drains every month on a visit to your property. We can also carry out an additional visit before or after a storm has hit if so required.

Why autumn is the riskiest season for empty homes in Athens

Like many Greek towns and cities, Athens is characterised by a long dry season during the summer months followed by short, intense rainfall events during the wet season (October to February). In general, the rainfall has decreased in recent years and is characterized by short duration downpours. On average, the rainfall in Athens totals 464 mm (38 rainy days) per annum. In terms of monthly averages, December is the wettest month with an average of 66.6 mm followed by November (50.6 mm) and October (47.7 mm). In contrast July averages only 4.2 mm (k24.net, 1961–1990 averages).

Recent storms show how quickly averages stop meaning anything:

  • Storm Byron (4–5 December 2025). Vlichada measured 245 mm on Thursday evening and Friday morning. 112 alerts were announced for residents in Megara and Mandra to move people in basements and ground floor apartments to higher floors (Capital.gr).
  • 21–22 January 2026. Heavy rain in Papagou. In a few hours 146 mm of rain must have fallen. The overflow of streams and of the local drainage system led to severe problems. A woman died in Glyfada (CTIF).
  • Upper Glyfada. A heap of building debris which was washed down the slopes of Hymettus by heavy rain, filling the streets of the area and overflowing from the drainage systems. This is the kind of terrain your apartment building is situated on, should you own a property on the Athens Riviera (To Vima).

Almost every severe flood in apartments comes from rain from a small storm, which clogs the blocked outside drain.

How a blocked balcony drain floods an apartment

A balcony for example is meant to drain off water. The water then drains off through a small outlet, (the gutter), in a down pipe to ground level. In the summer months the gutter of the balcony can fill up with all sorts of items such as: leaves, dust, cigarette ends and even a bird’s nest or two. By the time the first rain of winter arrives the gutter is completely blocked!

But sometimes a lot of water pours out all at once. When the first big rain drops after summer fall on the balcony it starts filling with water because it cannot drain off because of leaves etc. The water goes up on the floor and at a certain point it flows into the apartment through the threshold of the door and ends up ruining the floors, walls and furniture. Moreover, if the owner of the flat below is not very friendly, the water can seep down to his/her apartment and cause damage as well. Thus, a simple clogged up drain can cause a big dispute between neighbors.

The same Civil Protection guidelines recommend checking if the drains and rain spouts outside your home are not blocked and are working properly. These are easy things to check when you live in a property but very difficult to check when you are abroad and therefore are frequently neglected.

Terraces and flat roofs: where leaks really start

There are often indicators as to whether there is any damage on the roof, in the terrace, or in the area around the drain. Discolored or bubbly paint, peeling plaster, mold, etc. appear first on the top floors (Praktiker). But when you notice water leaking from the ceiling, during or after a rainfall, then you know that you have an urgent problem.

Cracks in the seals of joints and upstands as well as blocked outlets are among the typical causes of a roof leak problem. Although older waterproofing membranes may deteriorate over time, the problem can appear unexpectedly in an empty property as a sudden, large leak developing from a small spot.

We have seen this pattern happen to members of Home Watch Athens. More details of this case will be provided below: what was found, when it was found, what owner was told and what was done to fix it. The owner’s names will not be mentioned.

“Almost every water problem that I encounter in apartments that are not occupied has small beginnings. They start with something apparently innocuous, like a clogged drain, a small crack in a terrace floor or a tiny stain. Throughout the summer none of these minor problems seem to matter but within a short space of time the first storm of winter arrives and they become big problems very quickly.”

Yanis, Founder of Home Watch Athens

Roof leaks in apartment blocks: who is responsible

Who pays for leaks originating from the roof of an apartment building? The issue of responsibility in such cases is covered by Law 3741/1929, mentioned above.

  • The roof or terrace is common property. In this case, the repair will be paid for by all co-owners of the building, in proportion to their shares, in accordance with Article 19 of Law 3741/1929 (source).
  • Terrace belonging to one flat. Balconies and terraces can be separate property forming part of an individual apartment, in which case that owner bears the cost.

This is based on your building’s title deeds and its building regulation. Ask your building administrator to provide you with a copy of your building’s Title Deeds and Building Regulation. If necessary, refer to your lawyer for clarification on the matter or even for a dispute which may arise.

Before the season: a pre-storm checklist

As the weather sets in do the following before the first heavy rainfalls in September or October:

  1. Check the drainage of all drains on the balconies and terraces. Open the covers of the drains and fill them with water in order to check if the water drains properly.
  2. Check the downpipes the outlets feed into.
  3. Inspect the top-floor ceiling as well as the roof edge for signs of water stains, bubbling paint or peeling plaster.
  4. Remove any objects (loose leaves, plant debris, etc.) on the balconies that may obstruct the drain. Take down light objects from the balcony or remove them from the floor and move them away from the balcony doors and low walls.
  5. Relocate below floor level valuables as well as floor level items. Move items away from exterior walls and doors.
  6. Ask the building administrator for your building about the condition of the roof and whether there are any planned works.
  7. Inform a local person of your instructions to clear drains before the bad weather arrives. He/she will need the keys, your approval to enter your property and a method of contacting you.

Home Watch Athens clears balcony and deck drains as part of our regular property inspections and members can also book a Home Watch inspection before or after a storm warning has been issued. All costs are quoted in advance and members can pay online. See our emergency property check service in Athens.

When a 112 warning arrives and you’re abroad

Depending on the country where you are staying abroad (your holiday home), the alerts will be distributed by the civil protection service to the cell phone numbers registered by the citizens or permanent residents of that area.

If you are away, do this instead:

  • Instead have someone else keep an eye on the weather forecasts and the disaster warning alerts for you.
  • If there is time before the rain arrives, ask them to also clear the balcony and terrace drains before it gets dirty.
  • After the initial clearance, also ask your watcher to inspect your property internally to check for any possible water damages or other effects and to also take and send to you dated photos of all interior areas.
  • Don’t send them into danger. They should avoid going into basements and should stay away from flooded streets and roads until they are considered safe. No item in your flat is worth risking a person’s life or safety.

Read: how to carry out an emergency disaster home check within the first 24 hours of an emergency.

After the storm: what to check and photograph

Go through the flat in this order and take dated photos of everything:

  1. Check if there is any water in your balcony, make sure the drain is working properly and the outdoors area is clear from any obstacles or material that may clog it.
  2. Ceilings and walls, especially on top floor flats and those beneath balconies and terraces.
  3. Floors near balcony doors and windows for signs of damp or raised boards.
  4. Electrics. Is the panel / and all sockets OK and not contaminated. DO NOT USE IF WET!
  5. Anything that smells musty.

Even if everything seems to be in order, it is wise to take dated photos of all aspects of your home, be they good or bad. This is especially the case should you later need to make a claim on your home insurance, as the Financial Ombudsman Service advises that timing is crucial in assessing leaks.

Dry out wet areas within 24 to 48 hours. Most damage from wet materials can be reversed within this time frame, and, in most cases, the material will not develop mold (US EPA guidance). We describe what to do if your Athens home or apartment is flooded in our flooded property guide and manage the repairs from abroad in our emergency repair management for overseas owners guide. A new Blog will be published shortly entitled the humble home to damp and mould in an empty Greek home.

Our comprehensive property management services and House Watch services provide Athens property owners with an accountable ‘point of contact’ should something go wrong during the stormy winter months. We cover this in more detail on our Property Management Athens and Home Watch Athens pages.

This is general information only, and should not be used as authority to make a decision or as a substitute for legal or insurance advice. For authoritative information on building regulations or on how to deal with water leakages in your building, refer to your building’s regulations or consult with a lawyer. For authoritative information on how a claim under your policy would proceed, refer to the wording of your policy.

Frequently asked questions

How do I stop my balcony flooding while I’m away?

Clear the balcony and terrace drains before the first autumn rains and check them out after every storm.

Who pays for roof waterproofing in an apartment block?

According to building regulation usually all owners will be responsible for repairing waterproofing damage in equal proportion to their share.

What action can a foreign owner take during a storm alert overseas?

The measure can be organized by your home watch representative before the first autumn rains. However, he or she would need to check the drains before the storm, and to take photos inside the apartment after the storm.

How quickly does water damage turn into mould?

Wet materials must be dried within 24–48 hours to prevent the growth of mold.