How do you calculate gallons of water in a well?

PlumbingPrivate Well Water Systems

Well Volume Calculator

Calculate total standing water volume inside a drilled private water well and determine the exact bleach dosage needed to shock chlorinate for bacteria.

Plumbing Field StandardsPrivate Well Water Systems

Engineering formulations calibrated to IPC, UPC & NEC specificationsSub-Zero Cold Climate Tolerances

Quick Summary & Key Answer

A standard 6-inch drilled well casing holds 1.47 gallons of water per foot of water depth. For example, a 150-foot well with a static water level of 50 feet has a 100-foot water column, containing approximately 147 gallons of standing water storage.

4-inch casing holds 0.65 gal/ft.
6-inch casing holds 1.47 gal/ft.
Shock chlorination requires 3 pints of 6% chlorine bleach per 100 gallons to achieve 200 PPM disinfection.

Interactive Calculator

Adjust inputs for real-time results

Well Casing Diameter

Total Well Depthfeet

feet

Static Water Level (Depth to Water)feet from surface

feet from surface

Calculated OutputWater Volume Verified

Standing Water Storage

162Gallons

Standing Water Column Height: 110 ft
Storage Capacity per Linear Foot: 1.47 gal/ft
Bleach Required for Shock Chlorination (200 PPM): 2.4 quarts (0.6 gal)

Note: Use non-scented, standard 6% household bleach. Circulate water through an outdoor hose back down the well casing until chlorine odor is detected.

How to Shock Chlorinate a Private Well Safely

Shock chlorination eliminates coliform bacteria and iron/sulfur slime from drilled wells. Pour the calculated bleach volume diluted in 5 gallons of water down the well casing, hook a garden hose to an outdoor bibb, and recirculate water back into the casing for 30 minutes to wash down the walls.

Alaska Pro-Tip: Never drink or bathe with chlorinated water during the 12-24 hour contact soak period. Bypass water softeners and reverse osmosis filters before shocking.

Frequently Asked Questions

Common questions regarding this calculation and code compliance

Subtract the static water level from total well depth to find the water column height. Multiply water column feet by 1.47 for a 6-inch well (or 0.65 for a 4-inch well) to determine total gallons.