After the dry summer, test your sump pump before the autumn rain

Talking about flooding in the middle of a drought may sound odd. Yet this is exactly the right time. After the summer we have just had, two things are working against cellars, garages and plant rooms: soil so dry that it lets the first showers run off, and sump pumps that, for lack of water, may not have started since the spring. Here is why, and how to check your installation in a few minutes.

The Royal Meteorological Institute (RMI) considers summer 2026 probably the hottest ever observed in Belgium since records began in 1833. At Uccle, the period from 1 July to 15 August was the third driest since 1892. And September has not made up the shortfall: on 14 September, RMI meteorologist Pascal Mormal placed 70 to 80% of the country in a rainfall deficit, with a striking contrast between the north, where up to 56–57 mm has fallen locally since 1 September, and the Gaume, which has had only 1 to 2 mm.

In Wallonia, the drought cell that met on 9 September expects the situation to last until the end of the month; sixteen municipalities are still restricting certain uses of water. In Brussels, the yellow drought alert was maintained on 10 September. For this week, the RMI forecasts a temperature drop of more than 10 °C from Wednesday, with some rain, but no lasting return of wet weather yet.

You might think thirsty soil drinks whatever falls on it. The opposite is true. Dried out and cracked, it cannot absorb water straight away: in a heavy shower, the water runs off the hardened surface and gathers at the low points — paths, garage ramps, courtyards, cellar windows, sumps. It takes several hours of rain before the rewetted soil can store water again.

The Public Service of Wallonia points out that runoff flooding occurs when rain is too intense for the soil to absorb it, and that a violent storm can drop more than 100 mm in two or three hours. Nothing theoretical about it: during the storms of 30 May this year, firefighters had carried out more than a hundred call-outs in the Liège area alone by early evening, twenty-five of them to pump out water.

A sump pump is always called upon at the worst moment: when it is pouring, often at night, sometimes during a power cut. After months with no water in the sump, several things may have deteriorated silently: a float stuck by dried deposits or jammed against the wall, a seized non-return valve, a blocked impeller, an alarm with a flat battery, a breaker that tripped during a summer storm without anyone noticing.

None of these faults shows as long as it stays dry. They all reveal themselves at the same time as the water. Well and rainwater tank pumps that saw little use this summer deserve the same test before they are needed again.

Before touching anything in the sump, switch off the power to the pump; only switch it back on once your hands are out of the pit.

Remove any visible leaves, gravel and debris around the pump, and check that the float moves up and down freely.

With the pump powered, slowly pour a few buckets of water into the sump: the pump should start when the float rises, then stop by itself as the level drops.

Listen: a hum with no flow, a sound like gravel, or repeated short starts are warning signs. After it stops, water should not flow back into the pit; if it does, the valve needs checking.

Test the high-level alarm if you have one, then clear gullies, garage-ramp grates, gutters and downpipes: that is where the water comes in first.

If the pump does not start, runs without pumping, trips the electrics or lets water flow back into the pit, do not persist: a pump that runs dry or overloaded wears out quickly. The same applies if there is a thick layer of sludge in the sump or a strong smell.

For a commercial building, a block of flats, a farm or a sensitive plant room, autumn is also the time to consider whether an alarm, a second pump or a backup power supply is needed. Better to decide that with a clear head than with wet feet.

We install, maintain and repair sump pumps and lifting stations across Belgium, for private and professional customers alike. An autumn check does not stop at the pump: we check the float, the valve, the alarm, the power supply and the path the water takes to the sump. And if the water gets there before we do, our emergency service answers 24 hours a day, 7 days a week.

The drought will eventually give way to rain. Better for the pump to be ready that day.