Quick Answer
Adequate drainage around a cistern is crucial to prevent water accumulation and potential structural damage. To ensure proper drainage, a slope of at least 1% is recommended to allow water to flow away from the cistern. Regular maintenance and inspections are also necessary to prevent clogging and ensure the drainage system remains functional.
Setting the Slope
When installing a buried concrete cistern, setting the correct slope is critical for proper drainage. A minimum slope of 1% is recommended, which translates to a drop of about 1 foot in 100 feet. This means that for every 100 feet of cistern length, the bottom of the cistern should be at least 1 foot lower. To achieve this slope, the surrounding soil can be excavated and filled with a mixture of soil and gravel, or a concrete footer can be poured to create a slight incline.
Drainage Pipe Installation
A properly installed drainage pipe system is essential to direct water away from the cistern. A 4-inch diameter pipe is a good starting point for most cisterns, but larger pipes may be necessary depending on the cistern size and expected water flow. The pipe should be sloped at a minimum of 1% and directed towards a natural watercourse or a sump pump system. To prevent clogging, a 100-foot section of pipe should be equipped with a cleanout access point.
Regular Maintenance
Regular maintenance is crucial to ensure the drainage system remains functional and prevents clogging. The drainage pipe should be inspected annually, and any debris or sediment should be removed. The slope of the cistern should also be checked to ensure it remains at the recommended 1%. Additionally, any signs of water accumulation or structural damage should be addressed promptly to prevent costly repairs.
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