Start Before the First Hard Frost

There is a particular kind of February misery that begins with a cracked filter housing in November. Water expands as it freezes, and that expansion is patient and relentless: it will split a length of hosepipe, push apart a compression joint and crack the impeller chamber of a pump left sitting in a shallow reservoir. The good news is that a couple of hours on a dry afternoon in late October or early November, before the first proper frost, is usually all it takes to avoid the whole business. Work through the checks below in order, and you can shut the gate on the water garden until spring.

Pumps: To Run or To Lift?

The answer depends on the depth of your pond and what is living in it. As a rule of thumb, a pond around 60cm deep or more will hold fish comfortably through a UK winter, but the water stratifies: the coldest, oxygen-rich layer sits at the top while the warmer, denser water settles near the bottom. If your pump is sitting flat on the base, it will stir that warmer layer into the cold and drop the whole pond a degree or two. Either raise the pump onto a plant basket or a brick so it sits 30–45cm below the surface, or switch it off entirely.

If you do switch off, lift the pump out rather than leaving it in the water. Clean the impeller and the intake sponge in a bucket of pond water, check the cable for nicks where it passes over the liner edge, and then store the pump fully submerged in a bucket of pond water somewhere frost-free. Storing a pump dry is a common mistake: the shaft seals and rubber O-rings shrink and harden, and you will find out about it in April when the thing grinds and leaks.

Filters, UV Clarifiers and Bio Media

Pressurised filters and box filters are the most frost-vulnerable kit in the garden, because they hold water in every awkward corner. Drain them completely, open any drain taps, and tip them to empty the pipework. If you are shutting the pond down for the winter, clean the mechanical media and store the biological media in a bucket of pond water indoors — never rinse it under the tap, as chlorine will kill the bacteria you have spent all summer cultivating.

• Remove UV bulbs and quartz sleeves, dry them and store them indoors in a padded box.
• Leave the filter casing somewhere dry and covered, with the lid off so any residual moisture can escape.
• If you run the filter year-round, lag the housing with bubble wrap or an old duvet cover and check it weekly after heavy rain.
• Note the condition of seals and clamps now, and order replacements while stocks are still good.

Pipework, Joints and Jubilee Clips

Flexible hose and rigid pipe are where frost causes the most expensive, hardest-to-find damage. Any low point, sag or dip in a run of pipe holds a plug of water that will freeze and split the wall. Disconnect every length you can and lift it clear, then drain it by holding it up and walking the water out. Where pipework has to stay in place, angle it so it drains, or blow it through with a gentle puff of air.

Insulate exposed runs with foam lagging, and pay extra attention where pipes cross open ground or sit above the water line. Check every jubilee clip and hose tail while you are there: plastic hose tails go brittle in cold, and a clip that felt tight in July may be loose enough to pop off in January. A handful of spare clips costs pennies.

Fountains, Waterfalls and Ornamental Features

Small self-contained features — a spouting lion, a millstone, a glazed pot with a bubble pump — should be emptied and stored dry. Water left standing in a stone or resin bowl will freeze, and a full bowl can crack from the inside out. Remove the pump, drain the reservoir, and cover the feature with a breathable cover or a sheet of plywood weighted down; this also keeps leaves and heron-hunting cats out.

If water runs over a cascade or a slate chute, switch the pump off, drain the top pool, and lift the pipework clear. Constant running water through a hard frost builds ice that can shift rocks and lift liner edges.

Ice, Wildlife and a Final Walk-Round

Once the ice arrives, resist the urge to break it with a broom handle or a boot. The shock waves stress fish and can damage the pond liner. Float a pan of hot water on the surface, or use a purpose-made pond de-icer, to keep a small hole open for gas exchange.

• Keep a shallow ramp or a piece of floating timber in the pond so hedgehogs and frogs that fall in can climb out.
• Leave a dish of fresh water near the ground for birds and mammals when everything else is frozen.
• Check the pond after every hard frost: look for cracked fittings, sagging covers and water loss.
• Put a note in the diary for late February to check pumps and filters before switching anything back on.

Ten minutes of checking now, with cold fingers and a torch, is a great deal cheaper than replacing a pump, a UV unit and a run of pipework in the spring. Your water garden will thank you for it.