Pump and Tank Buying Guide

Pumps and pressure tanks aren’t usually the topic of everyday discussion, unless you happen to be a plumber. Most people don’t really even give them a second thought and that can make selecting one a little confusing. With all the different types and sizes available it can seem as though you need a degree in hydro engineering to make the right choice. Don’t be intimidated by all the choices and plumbing lingo, use our guide to help you make an informed decision.


Float switch – A switch that turns a pump on and off as the water level rises and falls.

French drain – A gravel-filled drainage system designed to channel water away from a structure or to a pump basin under the structure.

Lift – The vertical distance from the water level to the highest point to which water is pumped.

Impeller – A disk with curved veins connected directly to a pump’s shaft, generating the pumping action.

Well Pumps

Well pumps are available in different sizes and horse power (hp) ratings. As a rule higher hp pumps can move more water at greater lifts (heights). Well pumps are usually either submersible pumps or jet pumps:

  • With a submersible pump the entire unit is submerged in the well. Submersible pumps have a series of impellers that draw water from the well and push it up through the pipe leading to the home. Submersible pumps can obtain upwards of five-hundred feet of lift for really deep wells.

  • With a jet pump the motor and all electrical connections are above ground. There are two different types of jet pumps.

o Shallow well jet pumps - for wells with water levels less than twenty-five feet deep. Shallow well jet pumps create a vacuum that draws water up from the well and pushes it through to the home’s holding or pressure tank.

o Deep well jet pumps - for wells with water levels between twenty-five and one-hundred feet deep. In addition to creating a vacuum to pump water from the well, deep well jet pumps also push water back down through a return line that’s connected to the suction line. The added pressure from the pump pushing water through the return line enables the pump to draw water from greater depths at higher flow rates.

When selecting a well pump keep in mind that it should be capable of pumping one gallon of water per minute (gpm) for each plumbing fixture it supplies, including outside spigots. The vertical distance from the water level in the well to the highest point to which water is pumped is the total lift and must be taken into consideration when selecting a pump. Don’t make the mistake of purchasing a pump that’s too powerful. An oversized pump will cycle on and off (cut in and cut out) too often, stressing the pump motor and leading to early failure.

Sump Pumps

Sump pumps are usually used to pump water from basements or crawl spaces. They are available in a wide range of sizes and generally follow the rule that the faster and greater volume they can pump the more they cost. Most sump pumps have a float switch that turns the pump on and off as the water level rises and falls. In a typical installation the pump is placed in a sump basin below the floor level in the basement or crawlspace. Ideally, the floor should be sloped toward the sump basin so all water flows to the basin for removal by the sump pump. In many areas, especially those with high water tables or significant water from spring thaw and runoff, there will also be a French drain around the house or structure that drains into the sump basin. As the water rises in the sump basin it causes the float switch to rise and activate the pump. The pump removes water until the float switch falls. Sump pumps are available in two basic configurations:

  • Submersible pumps that are sealed and can be totally submerged.

  • Pedestal pumps that have their pumps at the bottom of a stand and their motors elevated.

When replacing a sump pump, it is generally advisable to use a pump of the same type, pumping capacity and configuration to make the replacement simple. When choosing a pump for a new installation you should determine the amount of water and frequency of flooding events you anticipate. Your local building authorities or a professional installer can help you estimate. Then choose an appropriately sized pump. Don’t make the mistake of purchasing a pump that’s too powerful. An oversized pump will cycle on and off too often stressing the pump motor and leading to early failure.

Utility / Specialty Pumps

Utility pumps are available in a wide range of types from hand powered bilge pumps to gasoline powered pumps for draining low-lying areas. Most utility pumps run on electricity and are typically used for transferring liquids between containers, draining pool covers or tarps and other job specific uses. When purchasing a specialty pump, choose the pump with uses most closely matched to your needs.

Sewage Pumps

Sewage pumps are designed to pump sewage and/or waste water in situations where the connection to a municipal or private septic system is at a higher elevation than the home’s main drain. Typically, the main drain empties into a holding tank where the sewage pump is located. A float switch wired to the pump acts an automatic switch, turning the pump on and off as the level in the holding tank rises and falls. Since these pumps move sewage as well as water, they are rated for the size of solids they can move as well as how much water and lift. Always contact your local building authorities or health department before beginning work on sewage or septic systems.

Swimming Pool Pumps

Swimming pool pumps disperse and mix chemicals, power the pool’s vacuum system and provide for drainage and backwashing. Your choice of swimming pool pumps should be based on the pool’s holding capacity in gallons. Pump manufacturers provide tables with the capacity range for their pumps so all you need to do is match your pool’s capacity to the correct pump range.

Lawn Sprinkler Pumps

Lawn sprinkler pumps are used to pump water to lawn sprinkling systems. These pumps can be used to draw water from wells, ponds, lakes, cisterns or tanks. Keep in mind that sprinkler pumps are restricted to a twenty-five foot lift. When selecting a lawn sprinkler pump you will need to know three things; the total length of the sprinkler system’s longest pipe run, the pipe diameter and the collective capacity of the sprinkler heads in gallons per minute (gpm). Most manufacturers provide a chart you can plug the information into to size your pump.


Pressure tanks are typically used in conjunction with private wells. The tanks provide consistent pressure to the home’s water system within a range of approximately 20 pounds per square inch (psi) and also act as reservoirs, holding extra water in the system. Most home water systems are set up so the pump turns on (cuts in) at 20, 30 or 40 psi and turns off (cuts out) at 40, 50 or 60 psi, respectively. There’s a diaphragm in the tank with pressurized air above the diaphragm and a water holding area below.

  1. As the water holding area fills, the diaphragm is forced up, increasing the pressure and charging the plumbing system with greater pressure.

  2. Once the system pressure reaches the pump cut out pressure the pump stops.

  3. Water is drawn from the pressure tank without the pump cutting in until enough water is removed from the water holding area to decrease the system pressure to the pump cut in level.

  4. After the pump cut in level is reached the pump comes on and runs until the system pressure is equal to the pump cut out level.

The tank allows water to be drawn from the system without the need for the pump to cycle on and off each time the water is turned on. Reducing on and off cycles cuts down on wear and tear and prolongs the pump’s life. When choosing a pressure tank you will need to know the gallons per hour (gph) your pump pushes in your plumbing system and the number of plumbing fixtures, including outside spigots, in the system. Most manufacturers produce a chart that you can plug those numbers into to size your pressure tank. Just remember that if you’re in doubt about the size tank you need, it’s always better to go larger with pressure tanks. Larger tanks hold more water and reduce the number of times the pump is required to cycle on and off.

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