Gary C. Tanko Well Drilling, Inc.
The trusted name in water well drilling, pump sales, service & installation since 1969.
Capacity Requirements

The capacity required of the water system depends upon the water-using fixtures and the number of people or animals consuming the water.  The most important consideration is the demand requirement. This means the amount of water required in a given period of time. In a home, for instance, most of the water is used in the morning shortly after everyone awakens and in the evening around the dinner hour. Motels and hotels have similar demand periods.

Peak periods usually last from 30 minutes to two hours.  During this time, the "water system" must meet the demands of those using the system. This means the combination of the well, the storage tank and the pump must produce the water continuously. Special or emergency demand required for fire fighting purposes should also be planned for farm installations.  For home installations, the demand period lasts for about one hour.

If the rate of flow required during the demand period exceeds the maximum rate at which water can be drawn from the well, the difference must be accomplished so the user will continuously obtain water under pressure.

The capacity of the system is expressed in gallons per minute (gpm). The system in a home should be capable of delivering the required capacity continuously for a period of one hour. Motels and farms require the capacity for periods of two hours. A system with a smaller capacity will not provide an adequate or convenient water supply.

A practical and generally accepted rule for determining the capacity for a home is: The capacity of the system in gallons per minute should equal the number of fixtures installed, but not less than the peak demand for the largest single fixture. For this purpose, "fixtures" are defined as outlets. They may be inside or outside faucets, washing machines, toilets, lavatories or sinks, and the like. Even if there are two faucets – one for hot and one for cold water – on a sink or other fixture, these are counted as one outlet for this purpose.

As an example, in a small home with one bathroom, (including a bathtub, toilet and lavatory), one outlet in the kitchen and one outside hose bib, a water system with a capacity of 5 gpm would be required. The system should be capable of delivering the 5 gpm (or 300 gph) continuously for one hour for a total usage of 300 gallons.