Quick Answer
You can use a concrete cistern for drinking water, but you must ensure it meets strict safety standards. A well-maintained, properly sealed, and tested concrete cistern can be a safe and reliable source of drinking water.
Concrete Cistern Requirements
A concrete cistern intended for drinking water storage must be specifically designed and constructed with materials that meet or exceed NSF/ANSI 61 standards for safe drinking water contact. The cistern’s concrete must be formulated with potable water-grade aggregates and cement, and all joints and seams must be properly sealed to prevent contamination.
Installation and Maintenance
When burying a concrete cistern, it’s essential to follow a few key guidelines. First, the cistern should be installed at a depth of at least 12 inches below grade to prevent freezing and root intrusion. The surrounding soil should be compacted and graded to ensure proper drainage, and a 12-inch thick layer of impermeable material (such as compacted clay or a geotextile fabric) should be placed between the cistern and the earth to prevent leakage. Regular inspections and maintenance are crucial to ensure the cistern remains safe and secure. This may include checking for signs of cracks, corrosion, or other damage, and performing routine cleaning and disinfection to prevent bacterial growth.
Testing and Certification
To ensure the cistern meets drinking water standards, it should be tested and certified by a third-party laboratory. This may involve sampling the water for bacteria, viruses, and other contaminants, as well as testing the cistern’s materials for chemical safety. In some jurisdictions, concrete cisterns may also require registration or permitting, so it’s essential to check with local authorities to determine specific requirements.
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