A cesspool is an underground holding tank designed for the purpose of storing waste from a home without treating it. It is essentially a perforated concrete or block ring, similar to a well-liner but with holes, buried underground. Sanitary waste from toilets, sinks, and washing machines enters the cesspool and percolates out. While cesspools are designed to capture sanitary waste, they do not treat waste. As the solids accumulate, eventually the particulate solids block the escape of liquids, causing the cesspool to drain more slowly or to overflow. Cesspools were widely used as a means of waste disposal in the past, particularly in rural areas where there was no access to modern sewage treatment facilities. However, as awareness grew about the health risks associated with untreated sewage and wastewater, cesspools began to be phased out in favor of more modern sewage treatment systems. Today, the use of cesspools is largely restricted or banned in many areas due to concerns about groundwater contamination, the spread of disease, and environmental pollution.