Rowa pressure sensitive water pump used for water pressure boosting or rainwater harvesting (C) Daniel FriedmanPressure Sensitive Water Pumps
Tankless water pump systems use a control to omit the pressure tank

  • WATER PUMP PRESSURE SENSITIVE - CONTENTS: Pressure sensitive pumps and inline pump controllers can provide water pressure boosting, rainwater harvesting, or similar functions without requiring a water pressure tank. What are pressure sensitive pumps and what are inline pump controls, how do they work and where are they most often used?
  • POST a QUESTION or READ FAQs about pressure sensitive water pumps for rainwater harvesting or water pressure boosting; using an inline pump controller, omitting a water pressure tank.
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Pressure-sensitive water pump systems & inline water pump controllers:

This article explains how pressure sensitive pumps and inline pump controllers provide water pressure boosting, rainwater harvesting, or similar functions without requiring a water pressure tank. We explain pressure sensitive pumps and for similar as well as for higher water volume or pressure applications we describe inline pump controls, how they work and where are they most often used.

Our page top photo shows a model set-up for a Rowa brand pressure sensitive pump and control system suitable for water pressure boosting, cistern or rooftop water storage tank water delivery, or rainwater harvesting systems. This system can operate without requiring a separate hydropneumatic or water pressure tank.

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Pressure Sensitive Water Pumps

Water pump control that avoids needing a pressure tank (C) Daniel Friedman]Reader Question: I got rid of my pressure tank and now am having trouble with short cycling.

(July 5, 2015) Mike Lambadarios said:
Have had problems with water supply ended up doing away with the header tank and pressurised the system directly to the house.

Ran fine for quite a while but is now constantly short cycling,I removed the bladder tank and blocked off the fitting again ran fine for a while but now back to short cycling again. Was it a mistake to pressurise directly to the house and should I reinstate the header tank?

Reply: either install a water pressure tank (header tank) or install a pressure-sensitive water pump system.


Pressure-sensitive water pumps

You need either a pressure tank installed to prevent short cycling of the pump, or you need a special hydropneumatic pump control that combines the pump with a pressure switch - shown at left. This is essentially is a switch that can turn a pump on and off when needed without short cycling.

While there is a variety of tankless pressure boosting water pumps available, typically an electronic control built into or attached directly to the pump senses either a pressure drop or the flow of water when a faucet or fixture is opened in the building. The control turns on the pump and in addition the controller maintains constant water pressure until the fixture is closed.

The pump will then stop after a brief interval of a few seconds. A tiny built-in or attached pressure tank is factory pressureized at the "cut-in" pressure for the pump and forms part of the control that prevents rapid on-off pump short cycling.

Water pressure booster pumps are widely used with rooftop water tank systems, in buildings where municipal water supply pressure is low, on shallow well systems and driven point wells, in irrigation systems and in similar applications. Both tankless designs using an electronic pressure sensor and flow sensor and perhaps a tiny built-in pressure tank, and pressure booster systems designed to work with a separate water pressure tank (Amtrol) are available and are listed later in this article.

Pressure booster pump models, including the Walrus TQ series, include controls specifically designed to prevent the pump motor from cycling on and off (short cycling) when water is being run, enhancing the pump's ability to deliver water at a constant pressure.

The pressure operating range varies by pump design, brand, and model but pump pressure boost capacities are typically between 30 and 75 psi (supporting a water piping height of up to 170 feet) and deliver water at flow rates ranging from 17 to 70 gallons per minute depending on variables such as incoming pressure, pipe diameter, piping length and rise, etc.

In our photo at above left that silver domed gadget above the red pressure-sensitive water pump works with the silver micro-pressure tank to provide a boost to water delivered (typically) from a rooftop water tank. No water pressure tank is used with this system.

These systems are typically used as water pressure boosters and not as the primary water source pump. The little silver dome dome is a miniature pressure tank itself, pre-charged to 7 psi and the whole system is calibrated to avoid short cycling of the water pump.

Pre-charged pressure control on a pressure-sensitive water pump (C) Daniel Friedman Mexico This equipment is distributed by and is widely distributed in Mexico where often we want simply to boost the pressure delivered by a rooftop water storage tank. Keep in mind that the total flow rate and building water service from this sort of system is of limited capacity.

Often we see pressure sensitive water pumps or inline pump controllers used with rainwater harvesting systems and cisterns or rooftop water tank systems serving small buildings. Submersible models of these pumps are also available for installation in the water tank.

Similar devices are sold by Aqua Group in India: the Aquatex APS hydropneumatic system. This approach floats a very small internal-bladder type pressure tank atop the water pump. Other models are used in marine applications such as the Shurflo and the Jabsco.

Typically a check valve is also required with pressure-controlled water pressure booster or rainwater harvesting pump systems.

Inline pump controllers to avoid using a pressure tank

A third option might be to use an in-line pump controller. An inline pump controller can be added to an existing system and works with most water pumps.

The inline pump controller senses pressure changes similarly to the pressure-sensitive water pump system we described above, and turns the pump on or off as needed. Some inline pump controllers include an additional sensor to shut off the pump if the water supply is lost, thus protecting the pump from damage.

Pressure Sensitive Water Pumps Omit Water Pressure Tank: Brands & Sources

Water pressure booster pumps including models that omit the need for a separate water pressure tank are used as building water pressure boosting systems, irrigation system water pressure improvements, agricultural and horticultural applications, and in industrial processes requiring a constant water pressure and flow rate.

Water pressure booster pump without water tank at Amazon

Above is the Simer Water Pressure Booster pump illustrated by the manufacturer.

Water pressure booster pump without water tank at Amazon

At are two water pressure booster pump using a pressure-sensitive control and omitting the requirement for a water pressure tank. At above left are a 1 1/2 horsepower pressure booster pump suitable for a whole-house water system pressure boost, while at right in that illustration is the Simer 3/4 HP inline "on demand" pressure booster pump.

AMTROL Inc. Corporate Office 1400 Division Road West Warwick, R.I. 02893 Phone: (401) 884-6300 Email:, Website:, Amtrol RP-HP Pressureiser water pressure booster systems include a pressure boosting pump integrated with an Amtrol water pressure tank. The system is designed to boost building water pressure 50-50 psi above the incoming municipal-supplied water. Amtrol has offices world wide including Canada, Central America, Europe, Puerto Rico, Mexico, South America, United States

Aquatec 8800 Series Booster Pumps, Aquatec International, 17422 Pullman St., Irvine CA 92614, Tel: 800-975-9995, Website:

BurCam Pressure Booster pumps, e.g. Burcam Model 506532SS dual application pressure booster pump can be used as a water pressure booster pump or as a shallow well single-line jet pump; Bur-Cam Company, 2190 Boul, Dagenais West, Laval, Quebec, Canada H7L 5X9, Tel: 514-337-4415, Website:, also sold through re-sellers such as Northern Tool, Sears, Walmart

Dayton 4HFA8 booster Pumps sold through Grainger, Zoro, other retailers

Grundfos SCALA2 pressure pump being installed at a home in San Miguel de Allende, Guanajuato (C) Daniel Friedman

Shown above: a Grundfos SCALA2 tankless water press rue pump in process of being installed atop a home in San Miguel de Allende, Mexico.

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Water Pressure Booster Pump Installation Notes & Warnings

Generally your pump should be installed in a dry area, protected from the weather and from freezing.

Check the pump manufacturer's installation instructions for the proper location of check valves in the piping system. Some pressure boosting pump models include a built-in check valve while others require an external valve or if pumping from a well, a foot valve.

Watch out: Check the pump manufacturer's advice about the maximum allowable input water pressure. If you are using the pump to boost building water pressure, for safety you may be required to install a pressure reducer/regulator on the municipal water supply line to limit the water pressure into the pump to a maximum of 20 psi (or other pressure specified by the pump manufacturer.

Watch out: warnings in the installation instructions for some of the pressure booster pumps we examined advise that you should never allow the pump to run "dry" as the pump will be damaged. The pump body and suction line must be filled with water before the pump is turned on.

Watch out: sand and debris, such as from water obtained from a driven point well can damage the pump. If there is sand, sediment or debris in the water supply protect the pump with an appropriate filter on the suction side of the pump.

Watch out: for leaks in the plumbing system that can damage the booster pump or that may show up in response to new, higher water pressure levels in the building or due to banging pipes that may occur due to increased water velocity when the tankless water pressure booster pump is installed.

Pressure sensitive pump research

Rowa pressure sensitive water pump system omits the water pressure tank (C) Daniel FriedmanA look at some relevant patents, books and other documents can help us understand how pressure sensitive water pump controls work.

Pressure sensitive water pump sources

Pacific Hydrostar water pressure booster pump - at Harbor Freight Tools


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