I only worried about the pipes freezing after a cold wave was forecast for my empty rental

When you host a short-term rental, there can be a few days between one guest leaving and the next arriving.

“A cold wave is coming. What if the water meter freezes while the room is empty?”

“How much insulation is enough?”

Seoul City says frozen pipes are more common in homes left empty for a long time or with too little insulation.
Here’s a guide, based on Seoul City’s advice, to three ways to prevent a frozen meter, the four alert levels, and what to do if a meter freezes.

This is general information based on Seoul City’s guidance. Advice may vary by building and location.

Preventing a frozen water meter: know the four alert levels

How are freeze alerts determined?

Seoul City issues four levels—Watch, Caution, Warning, and Severe—based on the day’s forecast low temperature.
These thresholds are from a Seoul City post published in November 2023.

Seoul City says it issues alerts starting 7 days ahead when a holiday and cold wave are expected to leave homes empty for an extended period.
These thresholds apply to Seoul.
For rentals elsewhere, check your local water utility’s guidance.

Source: Seoul City Media Hub, “Temperatures plunge…Learn how to prevent water meters from freezing!” (2023.11.13) (Checked in early November 2026; thresholds may change each year.)

Which homes are most likely to have frozen pipes?

Homes left empty for a long time and homes without enough insulation are most at risk.
A 2023 post reported that an analysis of more than 7,700 cases from the previous winter found that 97% involved homes left empty for a long time or with insufficient insulation.
A 2016 post said that of 951 cases between November 15 and 22, 2015, 77% (732 cases) were due to insufficient insulation.
A room left empty for a few days between guests faces similar conditions, so it’s worth checking before winter.

Source: Seoul City Media Hub posts (2016.01.22, 2023.11.13) (Checked in early November 2026; figures reflect the time of publication.)

3 things to check before winter if your rental may sit empty

Prevent a frozen water meter: check these 3 things first

Check the meter box, exposed pipes, then the taps when the room is empty.

① Make sure the meter box is packed with insulating material, such as old clothes or cotton, and that the lid is covered with plastic or similar to keep cold air out.

If the insulation is damp or damaged, replace it with dry, intact material (wet insulation can freeze).

② Check that exposed water pipes, the bathroom, and the boiler are insulated, too.
③ During a cold wave, you can leave a tap running very slowly while the room is empty (more on this below).

Seoul City recommends all three steps.
Meter box locations and who maintains them vary by building. If yours is in a shared area, check with building management first.

Source: Seoul City Media Hub and Seoul City Environment website posts (2019.12.03, 2023.11.13) (Checked in early November 2026.)

Should I leave a tap running while the room is empty?

Seoul City recommends leaving a tap running very slowly when the alert level rises, even if you’ve insulated the pipes.
At Warning level (-10℃ ~ -15℃), leave a tap running in a slow trickle if the home will be empty for a long time, even after insulating it.
At Severe level (below -15℃), do the same even when water won’t be used for a short time, such as overnight or while you’re out.
A 2019 post described the flow as enough to fill a 200㎖ milk carton in 26 seconds.
Seoul City recommends using a bathtub or bathroom sink tap.

Source: Seoul City Media Hub and Seoul City Environment website posts (2019.12.03, 2023.11.13) (Checked in early November 2026.)