在清代，故宫里的铜缸，宫中的铜缸是由内务府统一管理的。每天一早，内务府官员便命令苏拉（杂役）从井内汲水，一担一担地把所有大缸灌满，以备防火之用。每年到了小雪季节，宫内的太监就要在铜缸外套上一层的棉套，上面再加上厚厚的缸盖；同时，铜大 缸下面的汉白玉石基座里还要放置一盆炭火，并保证使其昼夜不息地燃烧着。这样，通过双重保暖措施防止缸内存水结冰。保暖工作一直要到第二年的惊蛰时节才能结束，那时大地回春，气候已经逐渐转暖，太监们就会解去棉套，铜缸文化，撤去炭火。为了保证宫中有足够的水源用于灭火，当时在宫中设置了许多大缸。据《大清会典》记载，宫有大缸308口。但世事沧桑，由于各种原因的破坏，如今只剩下了231口了。这些大缸共分为铁、铜和鎏金铜三种。一般来讲，铁缸是明代时铸造的；铜缸有明代的，也有清代的；鎏金铜缸则均是清代铸造的。其中，以铜缸居多，所以人们习惯地称的铜缸。

In the Qing Dynasty, the copper tanks in the Forbidden City and the palace were under the unified management of the Ministry of internal affairs. Every morning, the officials of the interior government ordered Sula (the worker) to take water from the well and fill all the big tanks with one load of water for fire prevention. Every year, in the light snow season, the eunuch in the palace will put a layer of cotton jacket on the copper cylinder, plus a thick cylinder head; at the same time, a basin of carbon fire will be placed in the base of the white marble under the copper cylinder, and it will be kept burning day and night. In this way, double thermal insulation measures are adopted to prevent water in the cylinder from freezing. The work of keeping warm can not be finished until the second year of hibernation, when the earth returns to spring and the climate has gradually warmed, the eunuchs will remove the cotton padded jacket, the copper tank culture and the charcoal fire. In order to ensure that there is enough water in the palace to put out the fire, many large tanks were set up in the palace at that time. According to the book of the Great Qing Dynasty, there are 308 large tanks in the palace. However, due to various reasons of destruction, there are only 231 people left. These vats are divided into three types: iron, copper and gilded copper. Generally speaking, iron jars were made in Ming Dynasty; copper jars were made in Ming Dynasty and Qing Dynasty; gold-plated copper jars were all made in Qing Dynasty. Among them, most of them are copper tanks, so people are used to call them copper tanks.