At construction and infrastructure sites, groundwater often presents an invisible challenge. When an excavation pit fills with water, progress can quickly come to a halt. A dewatering pump provides the solution. This type of pump temporarily lowers the groundwater level so that work can continue safely and efficiently.

In this article, you’ll learn about the various pumps used in dewatering, what a dewatering pump does, how it works, and what to consider when selecting and maintaining one. We’ll also explain why a self-priming pump from Gorman-Rupp is a reliable choice for any dewatering project.

What is a dewatering pump?

A dewatering pump is designed to remove groundwater around an excavation or infrastructure site. The goal is to lower the water level temporarily so the soil remains stable and workable. This process is also commonly known as wellpointing, drainage, dewatering or groundwater control.

The various techniques used in dewatering, requires the use of various types of pumps.

Wellpointing is a technology where a network of vertical filter hoses or wellpoints draw water from the ground. The discharged water is then released into a drain, ditch, or temporary storage area.

(Horizontal-) drainage uses a series of horizontal underground hoses or pipes to extract the water. 

General dewatering refers to pumping surface water from an excavation pit or trench.

Common applications include:

• Foundation and basement construction
• Sewer and utility installations
• Road and railway construction
• Bridge and tunnel works

Depending on the groundwater depth and required flow, different pump types may be used.

Types of dewatering pumps

Self-priming pumps

These pumps can handle air and water simultaneously, and are the preferred choice when the water supply to the pump is intermittent. Gorman-Rupp offers wet- and dry self-priming pumps for this. The latter works with an additional vacuum priming pump, often also referred to as prime-assisted pumps.

Self-priming pumps are ideal for dewatering because they start quickly, require minimal maintenance, and are resistant to debris and solids. Moreover they offer high flow capacity, enabling fast dewatering.

Advantages:

• Automatic priming, even in dry conditions
• Rugged construction for continuous operation
• High flow design
• High reliability and easy access for service

Diaphragm pumps

A diaphragm pump uses a flexible membrane to draw and discharge water. It’s often used for small-scale or temporary dewatering projects.
This type performs well with heavily contaminated water, for example on muddy or silty sites.

Piston pumps

A piston pump uses one or multiple reciprocating pistons. On the suction stroke, water is primed into the cylinder and upon the discharge stroke, the water is pressurised and discharged.

This type of pump is commonly used for vertical well pointing, due to the pump delivering a high vacuum. The low discharge capacity makes them less suitable for other dewatering jobs where self-priming centrifugal- or membrane pumps are more suitable.

Submersible pumps

For deep excavations, a submersible pump may be used. It operates directly in the water and continuously removes groundwater. These pumps are effective at greater depths but require more maintenance and electrical power.

How a dewatering pump works

A standard dewatering setup consists of the following key components:

1. Wellpoints, horizontal filter tubes or suction piping installed in the ground or the well to collect water
2. A vacuum header pipe or hoses connected to the pump
3. The dewatering pump itself, which discharges the water
4. Discharge piping, often consisting of flexible hoses or rigid piping or a combination of these.

The pump creates a vacuum in the pipe network, drawing water from the source. The discharged water is typically pumped into surrounding surface water , or reused for dust suppression or irrigation.

A self-priming centrifugal pump from Gorman-Rupp can handle both air and water, ensuring a stable operation even under fluctuating conditions. This makes it ideal for construction sites that demand high flow rates, high reliability and uptime.

When to choose a dewatering pump

A dewatering pump is essential whenever groundwater interferes with excavation, foundation, or utility work. Key factors to consider include:

• The type of dewatering technique used in your project
• Soil type: sand, clay, or peat affect suction capacity and filtration.
• Water level and flow rate: high groundwater or large flows require stronger pumps.
• Project duration: for long-term use, an efficient pump with low maintenance costs pays off.
• Water quality: trash-handling pumps prevent clogging in dirty conditions.

Gorman-Rupp pumps are known for their high availability and service-friendly design. Thanks to their self-priming system, they require fewer interventions and deliver consistent performance throughout the project.

Importance of regular maintenance

Proper maintenance extends the life of a dewatering pump and prevents costly downtime.
Routine service should include:

• Checking hoses, seals, and valves
• Cleaning the casing and impeller
• Monitoring oil levels and shaft seals
• Inspecting filters and check valves

It’s recommended to have maintenance carried out by trained technicians. This ensures safety, energy efficiency, and reliable operation for future projects.

Advantages of Gorman-Rupp dewatering pumps

Gorman-Rupp pumps are built for performance and durability.
Main benefits include:

• Fast priming and high efficiency with dry self-priming design
• Minimal maintenance due to easy-access pump housing
• Long service life with quality materials and robust construction
• Handles solids and harsh conditions without clogging

These qualities make Gorman-Rupp pumps ideal for construction, industrial, and municipal dewatering projects where uptime and dependability are critical.

Conclusion

A dewatering pump is essential for any project where groundwater obstructs progress. The right pump selection determines both the efficiency and continuity of operations.
Gorman-Rupp’s self-priming centrifugal pumps provide the perfect combination of performance, reliability, and ease of maintenance. Their solid design and straightforward operation make them suitable for long-term, heavy-duty use.

Whether you’re working on an excavation, infrastructure project, or industrial site, a well-chosen dewatering pump helps you work safely, efficiently, and dry.

Horizontal Directional Drilling (HDD) has revolutionised how underground pipelines and cables are installed. By eliminating the need for open trenches, it reduces surface disruption, traffic closures, and restoration costs. At the heart of every efficient HDD setup is one crucial component: a reliable bentonite pump.

Bentonite, a clay-based drilling fluid, lubricates the bore, stabilises the hole, and carries drill cuttings to the surface. Handling this heavy, abrasive fluid requires durable, high-performance pumps that can maintain flow and pressure under harsh conditions. That’s exactly what Gorman-Rupp delivers.

The role of bentonite pumps in HDD

During horizontal directional drilling, bentonite pumps are responsible for:

• Circulating drilling fluid between the entry pit and recycling unit
• Managing variable flow rates during pilot boring, reaming, and pullback
• Handling abrasive slurry without clogging or loss of performance

Simply put, the pump is essential in any drilling operation. It must be reliable, wear-resistant, and ready for continuous operation.

The challenge of pumping bentonite

Bentonite slurry is thick, viscous, and abrasive. It wears down impellers, causes blockages, and can trap air in the suction line. Pumps often need to handle intermittent flow or even prologued dry-running periods, all without losing efficiency or reliability.

A pump failure can halt an entire HDD operation. That’s why Gorman-Rupp’s S-Line and E-Line PAV4 and PAV6 pumps were developed specifically for bentonite and HDD applications. These dry self-priming vortex pumps combine robust construction, intuitive operation, and low maintenance demands.

Built for continuous operation

In HDD environments, pumps often run 24/7 under variable loads. The PAV-series maintains consistent performance even during stop-and-go operation. Large oil baths, efficient cooling, and precision seals prevent overheating and cavitation.

Beyond HDD applications

While developed for HDD, Gorman-Rupp bentonite pumps are equally suited to mining, tunnelling, civil engineering, wastewater bypass, and industrial slurry applications.

Built on experience, engineered for reliability

With nearly a century of pump engineering expertise, Gorman-Rupp continues to set the standard for performance and reliability. From our European headquarters in Waardenburg, the Netherlands, we provide local service, spare parts, and technical support.

Contact Gorman-Rupp Europe today, our experts will help you find the right setup for your project.

Why choose Gorman-Rupp bentonite pumps

1. Dry self-priming vortex design – The PAV4 and PAV6 pumps use a vortex impeller that allows solids to pass freely. The built-in vacuum or compressor-venturi system enables quick priming even with an empty suction line.
2. Proven wear resistance – Abrasive materials like sand and gravel are no match for the reinforced impeller and casing.
3. Built for heavy-duty environments – Fully welded, hot-dip galvanised steel chassis provides maximum strength.
4. Easy maintenance – Quick service without dismantling pipework.
5. Unsurpassed priming : Gorman-Rupp’s proprietary TPAWS priming systems enables fast and trouble free priming under all conditions.
6. Sustainable power options – Stage V diesel or electric drive for low-emission operation.

The E-Line is Gorman-Rupp Europe’s electric mobile pump set range, built for projects where on-site emissions, noise levels and precise speed control matter. With an integrated variable frequency drive (VFD), easy to use controls and a whisper-quiet sound profile, the E-Line meets the requirements of urban infrastructure work, zero-emission zones and industrial sites where grid power is reliable. Built on the same proven self-priming pump technology as the diesel driven S-Line, the E-Line delivers comparable hydraulic performance with zero on-site CO2 emissions.

Built on the same proven pump platforms

The E-Line uses the Gorman-Rupp pump platforms as found in the S-Line series. This means hydraulic performance is largely comparable; you do not trade away flow, head or solids handling capability when you switch to electric. The same Eradicator and Eradicator Plus solids management systems are available, the same multi-vane or Vortex benefits, the same external shimless adjustment and cartridge seal technology and of course the TPAWS priming system on our prime-assisted models.

Integrated variable frequency drive and intuitive controls

The integrated VFD provides soft-start, energy-efficient part-load operation and continuous speed control. You can match pump speed precisely to required duty point at the application, which means lower energy consumption, less wear and a quieter sound profile. Soft-start eliminates the inrush current spike that on direct-on-line motor starts can disturb other site equipment or trip protection devices.

Controlling the E-Line pump sets is done through an intuitive control panel, making operating an E-Line electric sets just as easy as the diesel driven sets you are familiar with.

Zero on-site CO2 emissions

The E-Line produces no on-site CO2 emissions. For projects in zero-emission zones, in protected nature areas, in dense urban centres or inside industrial buildings, this is often a regulatory requirement, not a preference. Combined with electricity from a renewable source, the full lifecycle emissions are minimal.

Whisper-quiet operation

Sound levels on the E-Line are low enough to allow night-time operation in residential areas, work near hospitals and schools, and use inside enclosed industrial buildings without specific sound attenuation. This widens the operating window for projects that previously required complex noise mitigation.

Stackable design

The E-Line is engineered for compact storage and transport. The stackable enclosure design saves yard space, simplifies fleet logistics and allows efficient transport on standard trucks.

Service-friendly and durable

Like the S-Line, the E-Line uses removable cover plates, external shimless wearplate adjustment on most models and cartridge seal technology. Electrical components are housed in a protected control panel for easy access during inspection and service.

Typical applications

Construction dewatering with grid power available. Urban sewer bypass during gemaal repairs. Industrial process duties inside facilities. Permanent or semi-permanent installations where mobile flexibility is still needed. Operations in zero-emission zones. Projects with strict night-time noise limits.

Warranty and support

Up to 5 years warranty depending on model and terms. Supported by European assembly and testing, commissioning support, training through Gorman-Rupp Academy and parts logistics across Europe.

Frequently asked questions