Reservatório domiciliar
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The residential water tank calculator helps determine the required water volume for a household based on daily consumption per person, number of residents, and desired autonomy days. It is particularly useful for construction projects, renovations, or rural areas with irregular public supply. The calculation uses the formula Volume = (Consumption per person × Number of residents × Days of self-sufficiency), enabling practical planning of domestic hydraulic systems.
The tool operates using three main variables: average consumption per person (in liters/day), the number of full-time residents, and the period in days the family wants the tank to sustain demand. For example, if each person consumes 100 liters/day and there are 4 residents with 3 days of autonomy, the calculation will be 100 × 4 × 3 = 1,200 liters. This ensures the tank meets basic needs for potable water, cooking, and hygiene.
This calculator is often used in early construction stages to properly dimension accumulation tanks. However, the resulting value is a basic estimate and may not account for factors like consumption variations, wastage, or network pressure. For complex systems, it is advisable to complement with an engineer's analysis, particularly in regions with water restrictions or dry climates.
Frequently asked questions
What consumption per person should I use in the calculation?
The recommended average is 100 to 150 liters per person/day, according to Brazilian standards. Adjust for areas with water restrictions or more economical habits.
Should I include guests in the number of people?
No, the calculation considers only permanent residents. Add 10-20% extra for frequent visitors as a safety margin.
How to handle consumption variations?
The tool uses constant consumption. For better accuracy, sum actual uses (e.g., drinking, hygiene, irrigation) and adjust autonomy days as needed.
Should the tank be larger than the calculation?
Yes, adding 15-20% to the calculated volume is recommended to ensure safety against estimation errors or peak usage.