Well Water Systems: Pumps, Pressure Tanks, and Treatment

Updated April 2026 · By the PlumbCalcs Team

Approximately 13 percent of American households, primarily in rural areas, depend on private wells for their water supply. Unlike municipal water that is treated and monitored by the utility, well water quality and system maintenance are entirely the homeowner responsibility. Understanding how your well system works, what contaminants to test for, and how to maintain the pump and pressure tank ensures safe, reliable water supply and prevents the costly emergency of a failed well system during a cold winter night or holiday weekend.

How Well Water Systems Work

A typical residential well water system consists of the well itself (a drilled hole typically 100 to 500 feet deep), a submersible pump at the bottom of the well, a pressure tank in the house, and a pressure switch that controls the pump. When you open a faucet, water flows from the pressurized tank. As the tank pressure drops to the cut-in setting (typically 30 to 40 PSI), the pressure switch activates the pump, which pushes water from the well into the tank until the cut-out pressure is reached (typically 50 to 60 PSI).

The pressure tank contains a rubber bladder filled with air that maintains pressure on the water. Without the tank, the pump would cycle on and off with every small water draw, rapidly wearing out the pump and pressure switch. A properly sized pressure tank provides a drawdown capacity of 5 to 20 gallons between pump cycles, allowing the pump to run for sustained periods rather than short cycling.

Well depth: typically 100 to 500 feet for drilled residential wells
Submersible pump: sits at the bottom of the well, pushes water up
Pressure tank: stores pressurized water, prevents pump short-cycling
Pressure switch: activates pump when tank pressure drops to cut-in setting
Typical pressure range: 30/50 PSI or 40/60 PSI cut-in/cut-out

Pro tip: Check your pressure tank air pressure annually with a tire pressure gauge when the tank is empty (pump off, faucet open until flow stops). Air pressure should be 2 PSI below the cut-in pressure. Low air pressure causes waterlogging and rapid pump cycling.

Well Pump Types and Sizing

Submersible pumps are used for drilled wells deeper than 25 feet and are by far the most common type. They are sealed units that sit underwater at the bottom of the well, pushing water to the surface through the well casing. Pump size is rated in gallons per minute (GPM), and residential pumps typically range from 5 to 25 GPM. The required GPM depends on your household size and peak demand.

Jet pumps sit above ground and use suction to pull water from shallow wells (under 25 feet for single-line, up to 110 feet for two-line configurations). They are less efficient than submersible pumps and more susceptible to losing prime, but they are easier to service since they are accessible above ground. Well pump replacement costs $800 to $2,500 for the pump plus $500 to $1,500 for installation labor.

Submersible pump: for wells over 25 feet, most common residential type
Shallow well jet pump: for wells under 25 feet, above-ground installation
Deep well jet pump: for wells 25 to 110 feet, uses two-line system
Typical residential sizing: 10 to 15 GPM for most homes
Pump lifespan: 8 to 15 years for submersible, 5 to 10 for jet pumps

Pro tip: If your well produces less than 5 GPM, install a storage tank system that fills slowly and provides peak flow from the tank. This prevents the pump from running dry during high-demand periods and extends pump life significantly.

Pressure Tank Sizing and Maintenance

The pressure tank size should be matched to your pump capacity to prevent short-cycling. The general rule is a minimum drawdown of 1 gallon per GPM of pump capacity. A 10 GPM pump needs at least 10 gallons of drawdown. Since the usable drawdown is only about one-third of the total tank capacity, a 10 GPM pump needs approximately a 30 to 40 gallon pressure tank.

Pressure tank failure is indicated by rapid pump cycling, where the pump turns on and off every few seconds when water is running. This usually means the bladder has ruptured and the tank is waterlogged. A failed tank should be replaced promptly because rapid cycling overheats the pump motor and can cause premature pump failure, turning a $300 to $600 tank replacement into a $1,500 to $3,000 pump replacement.

Minimum drawdown: 1 gallon per GPM of pump capacity
Tank actual drawdown: approximately one-third of total tank volume
20-gallon tank: suitable for 5 to 7 GPM pumps
30-40 gallon tank: suitable for 8 to 12 GPM pumps
50-80 gallon tank: suitable for larger pumps or longer pump-off time
Tank replacement cost: $300 to $600 installed

Pro tip: Larger pressure tanks extend pump life by reducing cycling frequency. Upgrading from a 20-gallon to a 50-gallon tank costs only $100 to $200 more but can extend pump lifespan by several years by reducing start-stop wear on the motor.

Water Quality Testing and Treatment

Private well owners are responsible for their own water quality. The EPA recommends testing well water annually for coliform bacteria and nitrates at minimum. Additional testing for pH, hardness, iron, manganese, sulfur, and other contaminants should be done every 3 years or whenever you notice changes in taste, color, or odor. A comprehensive water test costs $100 to $300 from a certified laboratory.

Common well water issues and their treatments include hardness (water softener), iron staining (iron filter or oxidation system), sulfur odor (aeration or chlorination), acidic pH (calcite neutralizer), and bacterial contamination (UV disinfection or chlorination). Many well water systems benefit from a multi-stage treatment approach that addresses several issues in sequence. A water treatment professional can design a system tailored to your specific water chemistry.

Annual testing: coliform bacteria and nitrates, $30 to $75
Comprehensive testing: full mineral and contaminant panel, $100 to $300
Iron treatment: oxidizing filter or greensand system, $800 to $2,000 installed
UV disinfection: kills bacteria and viruses, $500 to $1,500 installed
Acid neutralizer: calcite filter for low-pH water, $500 to $1,500 installed
Whole-house filtration: sediment plus carbon, $300 to $800 installed

Pro tip: Test your well water before and after installing any treatment equipment to verify it is working correctly. Keep records of all test results to track changes over time and detect developing problems before they become health risks.

Seasonal Maintenance and Emergency Preparedness

Well systems require seasonal attention, particularly in freezing climates. Ensure the well casing extends at least 12 inches above ground and has a sanitary cap to prevent contamination. Insulate any above-ground pipes and the pressure tank if located in an unheated space. If extended power outages are common in your area, a generator or hand pump backup ensures water availability during emergencies.

Keep detailed records of your well system including well depth, pump depth, pump specifications, pressure tank size, and the dates and results of all maintenance, repairs, and water tests. This documentation is valuable for troubleshooting, insurance claims, and home sales. A well disclosure report is required in most states when selling a property with a private well.

Winterize: insulate exposed pipes and pressure tank in unheated spaces
Spring: test water quality after snowmelt and runoff season
Annual: check pressure tank air charge, inspect well cap, test water
Every 3 years: comprehensive water quality test
Generator sizing: minimum 240V, 30A for most well pumps
Maintain records: pump specs, water tests, repairs, and maintenance dates

Pro tip: Install a water level monitor in your well to track the water table over time. Declining water levels may indicate aquifer depletion, neighboring well interference, or changes in your well production that warrant investigation before the well runs dry.

Frequently Asked Questions

How often should I test my well water?

Test for coliform bacteria and nitrates annually. Conduct a comprehensive test including minerals, pH, and contaminants every 3 years. Test immediately if you notice any change in taste, color, odor, or if there is flooding near the well, or if a neighbor reports contamination.

How long does a well pump last?

A submersible well pump typically lasts 8 to 15 years depending on water quality, usage patterns, and proper sizing. Jet pumps last 5 to 10 years. Pumps in wells with sandy or mineral-heavy water wear faster. Proper pressure tank sizing that prevents short-cycling extends pump life.

Why does my well water have a rotten egg smell?

Hydrogen sulfide gas produced by bacteria in the well or aquifer causes the rotten egg odor. Treatment options include aeration systems that release the gas, oxidizing filters that convert hydrogen sulfide to filterable particles, or shock chlorination to kill the bacteria producing it.

How much does it cost to drill a new well?

Well drilling costs $15 to $60 per foot of depth, with most residential wells costing $5,000 to $15,000 for the well drilling, casing, pump, pressure tank, and connection to the house. Deep wells in hard rock formations or areas requiring significant excavation can cost $15,000 to $30,000.

What should I do if my well pump stops working?

Check the circuit breaker for the pump first. Then check the pressure switch contacts for corrosion. Check the pressure tank for waterlogging by pressing the air valve. If none of these solve the problem, call a well service professional. Do not attempt to pull the pump yourself without proper equipment.