Across Spain, a habit is taking hold as October approaches: filling the freezer with water bags. Originating in the United Kingdom and later picked up by media outlets such as OKDIARIO, this tip is reaching households anxious about their electricity bills. At first glance, the idea seems anecdotal, almost gadget-like, especially when the freezer already appears to be relatively energy-efficient.
In Spain, media outlets urge all households to keep these water bags in the freezer precisely in October, and this is no accident: the cold season approaches, appliances run more, and everyone is looking for the slightest measure to ease their budget. The trick of water bags in the freezer promises a more stable appliance, a less-stressed compressor, and, in the end, a few euros saved over the year. The question remains how a few litres of water can help a freezer.
Why water bags in the freezer in October in Spain
The principle, explained by OKDIARIO, is captured in one sentence: “Replace empty space with ice.” In other words, when you open the door, the less empty space there is in the drawers, the less hot kitchen air can enter. This air must then be cooled, so the compressor starts more often. With blocks of ice, the volume of free air decreases and the interior temperature fluctuates less.
By filling the empty spaces with frozen water, one creates a cold reserve that takes longer to warm up than air. Spanish media note that well-stocked drawers leave less room for room air to slip in with each opening. The motor exerts less effort, heats less, and, in the long run, its lifespan increases, according to supporters of this method.
How to fill your freezer with water bags safely
Before filling your freezer with water, one must choose the right bag. The DGCCRF reminds, since February 18, 2026, that only a material intended for contact with food is acceptable. These containers are identifiable by the fork-and-glass symbol or by the inscription “suitable for foods.” It sums up: “Whether you are a professional or a consumer, only use utensils and containers designed to cook or store food items,” to avoid exposing consumers to danger. For freezing, a specific indication is also required, for example a snowflake or a temperature range including -18 °C.
For this trick, Spanish recommendations refer to airtight freezing bags or clean plastic bottles, avoiding glass. When filling, don’t fill to the top: OKDIARIO suggests about three-quarters, because water expands when it freezes and can rupture the container. On No Frost models, experts also emphasize one point: never block the air outlets at the bottom of the freezer, so as not to disrupt the circulation of the cold.
Electricity savings: what do water bags really achieve
The figures advanced by OKDIARIO for this method are modest. The outlet notes a reduction of between 5 and 10 % of the freezer’s own consumption, equating to only 3 to 8 euros per year on the electricity bill. It also states that “the economic impact is very small, because modern freezers are efficient.” The main benefit would therefore be to spare the appliance and its motor.
Some French media outlets, such as Maison et Travaux or Pleine Vie, remind that filling the freezer with water can remain an interesting supplement, provided you do not block ventilation and that you remove the bags as soon as you store foods. They point out that a freezer set to around -18 °C, with seals sealing properly and the door kept open as little as possible, will have a much bigger impact on the bill than this simple water-bag trick.
Sources
- Maison & Travaux
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