What is systerns?

As an AI language model, I can provide you with information on "cisterns". A cistern, also known as a tank or water storage tank, is a large container or underground reservoir used to store and collect water. Cisterns are typically made of materials such as concrete, steel, or plastic and are often used in areas where there is limited access to fresh water or unreliable water supply. They can be used to store water for domestic, agricultural, or industrial purposes and can also be used to collect and store rainwater. Cisterns are an effective way to conserve and reuse water and are widely used in many parts of the world. However, cisterns require regular cleaning and maintenance to ensure the safety and quality of the stored water.