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A cold water flat is an apartment that has no running hot water.
In most developed countries, current building codes make cold water flats illegal, but they used to be common in cities such as Detroit and Chicago until the mid-twentieth century.
Typically, cold water flats did not have built-in showers installed; tenants who wished to bathe would heat pots of water by stove and add the heated water to a bathtub. They also typically had no central heating. Tenants would keep warm by use of kerosene, electric space heaters, hot water bottles, or electric blankets.
Source of the article : Wikipedia