Winter Ice Damage to Pond Equipment: How Minnesota’s Deep Freeze Could Cost You This Spring

After a winter like this one, many hands-on pond owners we’re talking to are rethinking their pond maintenance and their approach to winterization. Here are key strategies we’ve effectively used during water feature installations and our winterization services to protect your pond equipment from extreme freezing temperatures next winter:

1. Bury Plumbing Properly and Ensure Correct Pitch

A common issue we encounter is plumbing that looks like something out of a Dr. Seuss book—twisting and turning in all directions with no thought for drainage. Just because it’s outside doesn’t mean it shouldn’t be pitched correctly to prevent water from pooling. Any low spots in your plumbing can trap residual water, which expands when frozen and leads to pipe fractures.

The Fix:

• If you’re building a new pond or reworking your plumbing, ensure that all pipes are sloped slightly downward toward a drainage point so that no water is left sitting in the lines when they are winterized.
• For existing setups, consider re-routing pipes that have noticeable dips or low points.
• Alternatively, consider installing a relief valve in low-points so that water can be drained out of all low points in the plumbing.

(Building a new pond? Check out our Pond Building Calculator!)

2. Cap Plumbing for Winter to Keep Lines Clear

Even when pipes are properly pitched, moisture can still creep back in if the system isn’t sealed properly before winter. With the freezing this past year, even a small amount of water left behind can be just enough to expand and crack fittings, valves, or underground plumbing.

The Fix:

• After draining and clearing all water lines, cap them using threaded plugs or winter-specific plumbing caps.
• If you have an auto-fill line, be sure to shut it off and blow out any remaining water, just as you would with an irrigation system.

3. Remove Pumps and Shut Down Waterfalls Before Freezing Temps Hit

When left in freezing water, pumps are vulnerable to ice expansion, which can crack impellers, warp casings, and seize internal components. Even if the pump is partially submerged, the trapped water inside can freeze, leading to irreversible damage.

The Fix:

• Turn off waterfalls and skimmers before freezing temperatures arrive (typically by late October or early November in Minnesota).
• Remove the pump, drain it fully, and store it in a bucket indoors (some leave the bucket full of water with older pumps to keep seals from drying out).

4. Use an Aerator and De-Icer to Maintain Oxygen Exchange and Reduce Ice Stress

If you have fish, keeping a hole open in the ice is non-negotiable. But even if you don’t, keeping some water movement prevents extreme pressure buildup in the system and reduces overall stress on your pond liner, rocks, and structure.

The Fix:

• Install an aerator to keep water circulating beneath the ice and prevent stagnation. Place the aerator in a shallow area to avoid supercooling deeper water where fish may be overwintering.
• Use a floating de-icer in combination with an aerator to maintain an open hole and allow harmful gases to escape.
• Choose the right wattage for your pond size—smaller ponds (under 1,000 gallons) may need a 250-watt de-icer, while larger ones may require 750 watts or more.
• Position the de-icer and aerator in different locations for maximum efficiency. If they’re too close together, the aerator can cool the water too much, making the de-icer work harder.

The Wisconsin Department of Natural Resources states that aeration is one of the most effective methods for preventing winterkill in backyard ponds, as it keeps oxygen levels stable even during deep freezes (WDNR, Managing Wisconsin Fish Ponds).