Water Table

The water table is the upper surface of the zone of saturation in the ground — the depth at which the soil or rock beneath your property is fully saturated with groundwater. Above the water table, pore spaces in the soil contain a mix of air and water. Below it, every available space is filled with water. For private well owners, the water table's depth and how it changes over time is one of the most important factors affecting well performance.

How the Water Table Changes

The water table is not a fixed feature — it rises and falls in response to precipitation, drought, seasonal change, and human water use. After a wet season or heavy snowmelt, the water table rises as groundwater recharges. During drought or extended dry periods, the water table drops as water is used faster than it's replenished. In areas with heavy agricultural irrigation or dense well use, human withdrawals can cause sustained water table declines over years or decades.

Why the Water Table Matters for Well Pump Owners

A submersible well pump is set at a fixed depth inside the well casing — typically several feet below the static water level to ensure it stays submerged even when the well is being drawn down. If the water table drops significantly during drought or high-demand periods, the water level in the well can fall below the pump intake. When a pump draws air instead of water, it runs without the cooling and lubrication that the water provides. This causes the motor to overheat, often resulting in failure within minutes.

This failure mode — sometimes called running the pump dry — is one of the most common causes of premature pump motor burnout. It's also one of the most unpredictable, because a pump that has worked reliably for years can fail suddenly when drought conditions push the water table below the pump intake for the first time.

Measuring Your Well's Water Table Depth

A well contractor can measure the static water level in your well — the distance from the top of the casing to the water surface when the pump hasn't been running. This measurement, taken periodically, tells you whether your water table is stable, rising, or declining over time. If you're in an area that has experienced drought or you've noticed declining pressure during dry periods, asking your contractor to measure the static water level during their next service visit is worthwhile.