Well Water: Check Supply, Pressure and Safety Separately

A household well-water system has three separate jobs: obtain enough water from the ground, deliver it at useful pressure, and provide water that is safe for its intended use. A bigger pump does not necessarily solve a supply shortage, and good pressure does not establish drinking-water safety.

Before buying equipment, separate well yield, pump performance, and water quality. Each needs different evidence.

What supplies the water—and what moves it?

A well provides access to groundwater in water-bearing rock or sediment. Its casing and seal help protect that opening; where fitted, a well screen limits sediment entry. The pump moves water into the distribution system. Jet pumps sit above ground, while submersible pumps operate inside the well casing. EPA describes these components in its private-well guide.

In a conventional pressure-switch system, the pump feeds a pressure tank and household piping. Water entering the tank compresses an air cushion. That compressed air then pushes water into the piping when a tap opens. The switch starts the pump at its lower pressure setting and stops it at its upper setting. The tank buffers demand and reduces pump cycling; it is not a large reserve of usable water. Penn State Extension explains this operating sequence.

First check: Can the well meet demand?

Well yield is the maximum rate at which the well can supply water without the water level falling below the pump intake. It is not the same as the flow rating printed on a pump.

Demand also has a time component. A well yielding 1 gallon per minute could theoretically supply 1,440 gallons over 24 hours, but only 120 gallons during a two-hour period from that ongoing yield alone. Water already stored in the borehole or a storage tank can also contribute. Several simultaneous household uses can therefore exceed the available supply even when daily production looks adequate. Penn State’s low-yielding-well guidance distinguishes this peak-demand problem from total daily water use.

For an existing system, gather:

• The well completion report and original yield test.
• The static water level: the resting level after recovery from pumping.
• The pumping water level at a measured flow rate.
• How much water is used simultaneously, and for how long.

The difference between static and pumping levels is drawdown. The pumping level—not simply the drilled depth—identifies the water level from which the pump must lift water. Goulds Water Technology’s technical manual explains these distinctions.

If delivery fades during prolonged use, ask a well contractor to measure flow, water level and recovery rather than assuming the motor is failing. Drought, over-pumping, mineral deposits, biological fouling, sediment plugging and pump damage can all reduce production. Penn State’s rehabilitation guide recommends comparing current performance with the original well records.

For a genuinely low-yielding well, spreading out water use or adding a properly designed intermediate storage system may help. Such a system uses the well pump to fill a nonpressurized reservoir and a separate pump to meet household demand. A larger pressure tank alone generally provides too little additional storage to solve a substantial peak-demand deficit. Penn State describes these storage options.

Second check: Can the pump deliver the required flow at pressure?

Pump selection needs a duty point: a required flow at a required total head. Horsepower alone does not describe that performance.

For a typical submersible system feeding a pressure tank, a preliminary head calculation adds:

1. Vertical lift from the pumping water level to the tank connection.
2. Required pressure at that connection, converted to feet of water.
3. Friction losses through the actual pipe, fittings and valves at the selected flow.

For water, 1 psi is approximately 2.31 feet of head. As an illustrative calculation, a pumping level 100 feet below the tank, a required tank pressure of 50 psi, and an assumed 20 feet of friction loss at the target flow give:

100 + (50 × 2.31) + 20 = 235.5 feet of head.

The pump must supply the target flow at that head—not merely reach that pressure with no flow. Goulds’ technical manual provides the head definitions, pressure conversion and pipe-friction tables. These example values are not a recommended pressure setting or a finished pump specification. Final selection must also check the operating pressure range, changing water levels and the exact pump’s performance curve.

A weak tap can also reflect resistance downstream rather than inadequate well yield. Pipe friction, elevation and a restricted outlet all affect delivery. Note whether every fixture is affected and record the tank gauge reading while water flows before requesting a pump upgrade.

For tank replacement, compare usable drawdown rather than nominal tank gallons. For control replacement, check pressure-switch compatibility, not just the pressure numbers on the cover.

Third check: Is the well water safe?

In the United States, the quality and safety of water from private domestic wells are not regulated under the federal Safe Drinking Water Act; owners are responsible for their household supply. That does not mean local construction or testing requirements are absent. EPA’s private-well portal explains the federal distinction.

EPA and CDC recommend testing at least annually for total coliform bacteria, nitrates, total dissolved solids and pH, using a state-certified drinking-water laboratory. Ask the local health or environmental department what additional contaminants matter in your area. Test after well-system repairs, flooding or a change in taste, color or odor. CDC’s testing guidance also explains how to get help interpreting results.

Choose treatment from the laboratory findings, not from pressure symptoms or appearance alone. If results identify harmful germs or chemicals, use a safe alternative drinking-water source while obtaining local health advice.

A flooded well requires a different response from ordinary low pressure: stay away from flooded pump equipment, do not drink or wash with the well water, and obtain contractor assistance to clean and disinfect the well before restarting. EPA’s flood-response guidance sets out those precautions. Clear water alone does not establish safety; arrange testing and follow local health advice about returning the supply to use.

Keep a record that makes the next repair easier

Store the well log, pump model, installation depth, flow tests, observed switch settings, tank specifications and laboratory reports together. These records help distinguish a declining water source from a pump, piping or control problem—and prevent a mechanical repair from being mistaken for proof that the water is safe.