Household bleach can work, but it's not a perfect swap.

Yes, but you have to know what you’re doing and read the label carefully.

Plain, unscented chlorine bleach (sodium hypochlorite) will kill algae and bacteria just like pool shock. The catch is that most household bleach is only 6% strength, while pool shock is usually 10–12% or more. You’ll need about twice as much bleach by volume to get the same punch. Also, many brands add thickeners, scents, or “splash-less” chemicals that can turn your pool foamy or cloudy.

If you’re going to try it, buy the cheapest, plainest bleach you can find—no additives, no “outdoor fresh” nonsense. Use a pool calculator to figure out the right dose for your pool size. Pour it slowly around the edges while the pump runs.

This is a fine emergency hack if you can’t get to the store. But for regular shocking, pool shock is cheaper per gallon of active chlorine and won’t surprise you with foam.

Past that, don’t make this your routine. Pool shock is formulated to dissolve fast and stay potent. Bleach degrades quickly in sunlight and heat.