Why late September and not November
DANA season on the Mediterranean coast runs from late September to early November. The reason is straightforward: the sea is still warm after the summer, and when a pocket of cold air arrives high up, the contrast feeds storms that drop a lot of water in very little time.
That means the window for checking the house is now, while the sky is still clear. Once it is raining, climbing onto a terrace to clear a drain stops being maintenance and becomes a bad idea.
The terrace drain is point number one
On a terrace or a roof terrace, water has exactly one way out. If that drain is blocked with leaves, sand or a layer of wind-blown soil, the water stays where it falls and rises until it finds the first weak seal. Usually the one around the perimeter, and then it turns up on the ceiling of the flat below.
Clearing it takes minutes. What costs money is discovering it was blocked on the day forty litres fall in an hour.
Gutters, downpipes and inspection chambers
In a house with a plot, the whole run matters. The gutter collects, the downpipe carries and the chamber distributes. If any of the three is obstructed, the water overflows at the point before it. Lifting the chamber lid and looking costs nothing.
In urbanisations with pines, external downpipes collect needles that form a solid plug. In the dune areas it is fine sand doing the same job. Every area has its own enemy.
What to check from indoors
Traps on drains that have gone months without use dry out, and when the sewer fills with water the smell comes up through them. Running the water for a minute in each drain before the rain solves half the calls we get the week after a storm.
It is also worth looking at the seals on windows facing south and west. DANA rain does not fall vertically, it arrives driven by the wind and gets in through gaps that cause no trouble the rest of the year.
If you live on the ground floor or have a basement
Garages and ground floors in the Vega Baja are the first to feel a surge. If you have a sump pump, test it now rather than finding out in October that the float has seized. And if there is a grille at the garage entrance, clear it: it is the biggest drain the house has.
None of this is alarmism. It is the same maintenance you would do before a long trip, only with a date in the calendar.
What we do and what you can do
Clearing a drain, cleaning an accessible gutter and running water through the traps is perfectly manageable on a Saturday morning. It is worth calling when the chamber is full and will not empty, when the downpipe is still blocked after you have tried, or when a drain sends water back instead of taking it.
In that case a camera inspection saves breaking into anything blind, because the blockage is almost never where you think it is.