Design & DIY

How can we prevent our water supply from freezing?

We take our water from a shallow lagoon (only three to four feet deep). The lagoon freezes sometimes and we lose our water supply. What should we do to prevent this from happening?
—J.L., via e-mail

Sounds like a job for a bubbler: an air pump that keeps the area around the water intake from freezing. Check dock supply retailers, or companies such as Products, which sell gadgets and equipment for lakes and ponds, including Bubble Tubing, a “self-sinking flexible fine-bubble diffuser” often used for dock de-icing. Not only will a bubbler keep the ice away, but it will help to aerate the water, says David Milligan, the senior director of’s Atlantic-Eastern office. (First, call your local governing bodies—for example, your municipality, or your conservation authority, if you’ve got one—to make sure that using a bubbler in your area is environmentally responsible and that no permits are required.)

You’ll need a power source close enough to the lagoon to run the bubbler and, if you want to make sure the lagoon never freezes, you’ll need to keep the bubbler going all winter, says Max Burns, author of Country & Cottage Water Systems. With a lagoon as shallow as yours, once the water’s good and frozen, firing up the bubbler won’t thaw it out, although, as Milligan points out, you could use a thermostat controller to have the bubbler only turn on at very cold temperatures.

Don’t want to use hydro? Burns is keen on a windmill-driven air pump, a technology that’s sometimes used for watering livestock. “Windmills are nice to look at. It’s one of the things I’d like on my own property,” he says. Windmills are nicest to look at when they’re actually, well, windmilling, so don’t pursue this set-up if your cottage barely gets enough breeze to power a child’s pinwheel. “You’ll have to assess your wind situation. It’s probably more consistent to have the bubbler plugged in,” Burns admits. “But that costs more money. And quite frankly, it’s not as neat.”