How Does My Private Well Pressure Tank Work?

when wellwater enters your home it's

pumped into a pressure tank a pressure

tank serves two basic purposes first it

provides water storage and water under

pressure to your home when the pump is

not running in times of high demand it

also provides a reservoir of additional

water to help the pump keep up pressure

tanks operate by maintaining a range of

pressure in the tank that forces water

out into the line when a faucet or other

source is opened when the pressure in

the line drops below the low-end preset

level generally 20 to 40 PSI it engages

automatic controls and preset gauges

like the pressure switch here this

causes the pump to kick on and begin

pumping water into the tank and home

distribution lines the pump continues

running until the usage stops and or the

pressure in the line reaches the preset

high-end level generally 40 to 60 PSI

the minimum pressure has to be high

enough to lift water to the highest and

farthest point in the line the original

pressure tank was a single tank of

pressurized air that could have water

pumped into it because air compresses

but water doesn't pumping water into a

pressurized air tank compresses the air

even further the compressed air creates

the pressure needed to push the water

throughout your home many of these tanks

are still in use

today however over time the air can

dissolve into the water lowering the air

pressure in the tank and reducing the

amount amount of air in the tank when

this happens the tank is effectively

water logged and more air has to be

added to keep the tank functioning

properly thus requiring more maintenance

when your tank is water logged the

reduced amount of air means that using

water from the tank will quickly lower

the pressure in the tank so that the

pump will kick on to repressurize it

with less air in the tank your pump

Cycles on and off much more often which

both wastes energy and is hard on the

pump because of this issue these tanks

are rarely installed anymore to help

deal with the water logging problem and

to help the tank maintain its air for a

longer period of time a wafer or float

can be installed in a standard air tank

this separates the water and air with a

flexible barrier that keeps them in

their own compartments the advantage is

that the tank operates more efficiently

and will require less

maintenance today most new pressure

tanks are bladder tanks as the name

implies a bladder tank contains a

flexible bladder that permanently

separates the air and water the water

goes into the bladder which expands

against the air pressure in the tank as

water is used the air in the tank pushes

against the bladder so that water in the

bladder empties into the distribution

line as the bladder empties the pressure

in the tank drops to a point that the

pump kicks on to begin refilling the

bladder again there are number of

factors influencing tank size a low

yielding well for example would require

a large your tank for water storage that

way the pump can provide water at a much

lower rate to fill the tank when no one

is using water the pressure tank stores

the water and has it available during

times of higher

demand without a large pressure tank

water use would quickly empty the tank

requiring the pump to kick on and try to

keep up if the demand were high like

during a shower and your well only

produced a few gallons a minute it could

cause a supply

Interruption if well yield isn't a

concern then it might be possible to use

a variable speed pumping system and

controller to help maintain water

pressure the pump maintains the pressure

in the system and changes speeds to

match the changing pressure requirements

for these installations the pressure

tank is only a few gallons in size and

helps keep the pressure constant on pump

startup the private well class is a

collaboration between the rural

community Assistance partnership and the

University of Illinois through the

Illinois State Water Survey and the

Illinois Water Resource Center and

funded by the United States

Environmental Protection Agency the

views expressed here are solely from the

class authors and not endorsed or

reviewed by

uscpa for more information on private

Wells sign up for our free 10-week email

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