Cistern Capacity for Emergency Situations: What Is Adequate?

Cistern Capacity Formulas and Guidelines

When sizing a cistern for emergency situations, consider the 1-inch-per-person-per-day rule, which translates to 1 gallon per person per day for drinking, cooking, and hygiene. For a single-family household of four people, this equates to 4 gallons per day. Multiply this by 365 days to determine the annual water needs: 1,460 gallons per year. A 2,000-gallon cistern will supply this household for approximately 1.37 years, considering 10% annual water loss due to evaporation, sedimentation, and other factors.

Factors Influencing Cistern Capacity

Other factors to consider when determining cistern capacity include household size, water usage patterns, climate, and local water laws. In areas with low rainfall or high evaporation rates, a larger cistern may be necessary to ensure water availability during extended dry spells. Additionally, households with pools, hot tubs, or large gardens may require more water storage to accommodate these needs. When in doubt, consult local water conservation experts or use online cistern sizing calculators to determine the optimal capacity for your specific situation.

Cistern Design and Maintenance Considerations

While cistern capacity is crucial, proper design and maintenance are equally important to ensure water quality and safety. Consider using a first flush device to divert debris and contaminants from the roof, and install an aeration system to prevent stagnation and bacterial growth. Regularly inspect the cistern for signs of leaks, corrosion, or sediment buildup, and perform routine water testing to ensure potability. By combining adequate cistern capacity with proper design and maintenance, you can create a reliable and self-sufficient water storage system for emergency situations.