What is the water table?

The water table is the upper boundary of the saturated zone in unconfined aquifers — the depth below ground surface where soil and rock pores are fully saturated with groundwater. It fluctuates seasonally and in response to pumping.

What is static water level?

Static water level (SWL) is the standing-water level measured when the well is not being pumped. Record the exact measuring point, date, time and pumping status so repeated measurements remain comparable.

What is hydraulic head?

Hydraulic head is the elevation of the water surface in a well relative to a common datum (usually mean sea level). It equals land surface elevation minus depth to water when measuring a water-table aquifer.

How accurate is this calculator?

Arithmetic does not determine field accuracy. The result inherits measuring-point, survey-datum, instrument, well-construction, pumping and temporal uncertainty. Do not infer a site-wide water table from one well without hydrogeologic review.

What units should I use?

All four methods accept either feet or meters. Changing units converts the values already entered, and results are always shown in both units.

What is the hydraulic gradient method?

This page performs straight-line interpolation of hydraulic head between two wells, then subtracts that head from land elevation at the point. It is only an interpolation between the entered wells—not a groundwater-flow model.

Does a well level always equal the water table?

No. In an unconfined aquifer, standing level can represent the water table. In a confined aquifer it represents the potentiometric surface, which may be above the aquifer and can even be above land surface.

Can I find my water table depth by ZIP code or address?

No calculator can accurately determine a current static water-table depth from a ZIP code or address alone. Levels fluctuate seasonally and vary across local terrain, geology, perched zones and pumping cones. For local records, consult USGS monitoring networks, state well-completion reports or the USDA NRCS Web Soil Survey, then verify with a suitable shallow well measurement.

How do I calculate depth to water from well depth and water-column height?

Subtract standing water-column height from total well depth, then subtract casing stickup when both depths are referenced to the casing top. For example: 150 ft total depth − 40 ft water column − 2 ft stickup = 108 ft below land surface. Confirm that both measurements use the same well-bottom reference.

Water Table Depth & Static Well Level Calculator

Calculate depth to standing water from a documented well measuring point, or subtract hydraulic head from land-surface elevation. A well in a confined aquifer measures potentiometric level—not necessarily the water table.

Inputs

Measurement Units

Calculation Method

Top of Casing Elevation above Ground (ft)

Height of casing top above ground surface. Enter 0 if flush with ground.

Static Water Level — depth from casing top (ft)

Enter your measurements and click Calculate.

Reference and field limitation

Privacy: calculations run locally in your browser. The measurements you enter are not uploaded by this tool.

A consistent well measuring point is essential for comparable observations. See the USGS groundwater sampling protocol. For public monitoring wells and historical measurements, start with the USGS local water-table guidance and the USDA NRCS Web Soil Survey; neither replaces a current site measurement. USGS also distinguishes an unconfined water table from the potentiometric level observed in a confined aquifer; see its confined versus unconfined aquifer explanation.

Summary

How it works

Select the calculation method that matches your available data.
Enter the required measurements (depths, elevations, or hydraulic head values).
Click "Calculate" to run the hydrogeology formula instantly.
Review the depth to water table in both feet and meters.
Use the gradient method to interpolate depth at a point between two wells.

Use cases

Converting a measured static well level from casing top to depth below land surface.
Environmental site assessments requiring water table mapping.
Agricultural planning for irrigation and drainage design.
Screening field measurements before professional site evaluation.
Hydrogeology coursework and field data analysis.
Monitoring seasonal fluctuations in groundwater levels.
Comparing pre- and post-pumping static water levels.
Quick field checks during well installation or rehabilitation.

Frequently Asked Questions

Last updated: 2026-09-24 · Reviewed by Nham Vu