Rainwater tank: get gutters and filter ready before the rain returns

Since spring, rainwater tanks have mostly been drawn on without being refilled. Many are now at their lowest, or even empty. When the rain comes back for good, every litre will count. But it still has to reach the tank: after a dry summer and the start of leaf fall, gutters and filters are often blocked. Here is how to prepare your installation, and what is best left to a professional.

In Wallonia, the drought has not let up. In its 1 October update, the Walloon Public Service (SPW) lists seventeen municipalities restricting certain uses of water and forecasts dry weather until at least 7 October, with limited rainfall. The same day, the drought unit convened by Cortex found the situation unchanged; in Libramont and Rochefort, water distribution is still considered very worrying and tanker trucks continue to supply some neighbourhoods.

According to the SPW, groundwater levels should only start rising from late October, or even early November. The coming weeks are therefore when rainwater tanks get their chance to fill up: make sure nothing stops the water on its way.

The first showers after a long dry spell wash off everything that has collected on the roof: dust, moss, pollen, then dead leaves. If the gutters overflow, the water falls beside the downpipe. If the filter is clogged, it goes straight to the overflow, towards the sewer or soakaway. Either way, the tank gets almost nothing, exactly when it needs it most.

An almost empty tank has another weak point: the pump. If it kept starting while the level was too low, it may have drawn in air or sediment from the bottom. Better to check it before relying on it again.

Gutters and downpipes: remove leaves, moss and debris, check that the leaf guards at the top of the downpipes are not blocked and that water flows freely. A well-secured ladder and someone at the bottom are not a luxury.

Filter: whether it is a basket in the inlet chamber, a downpipe filter or a buried filter, take it out, empty it and rinse the mesh with a hose. Put it back properly: a badly seated filter lets leaves into the tank.

Overflow: check that the outlet is not blocked. When the tank is full, the excess must be able to drain away without backing up towards the roof or the cellar.

Pump: if the tank is empty, switch the pump off or switch the system over to mains water if it allows it, so that it does not run dry. Once the water is back, check that it starts, builds up pressure and stops by itself.

Lid and manhole: make sure they are properly closed and in good condition. A tank is a dangerous space, especially for children.

Never climb down into a tank, even an empty one: the air can be low in oxygen and a fall can be serious. Yet a tank at its lowest is the right moment for what cannot be done when it is full: removing sludge from the bottom, inspecting walls and connections, checking the pump float or the top-up system.

Also call a professional if the water in the tank smells bad, if the pump keeps starting, no longer builds pressure or trips the electrics, or if a crack makes the tank leak. For a farm, a commercial building or an installation that supplies toilets and taps, an annual check avoids unpleasant surprises.

We install, service and repair rainwater tanks and their pumps throughout Belgium. An autumn check covers the whole chain: water inlet, filter, tank, overflow, pump and, where relevant, mains switch-over and downstream filtration. Common filtration consumables are also available in our webshop.

The rain will come back eventually. It might as well fill your tank.