PUMP CATEGORY

Dewatering Pumps

Dewatering pumps are heavy-duty submersible pumps designed to remove water from construction sites, excavations, foundations, trenches, and groundworks. Built to handle silt, sand, sediment, and continuous duty in demanding site conditio...

Products in range 11
From £299.99£249.99 (Exc VAT)
Use case Construction
Warranty Up to 3 Years
11 products

Dewatering Pumps: Keeping Excavations, Trenches and Sites Dry

Dewatering is the controlled removal of groundwater and surface water from an excavation, trench, foundation or working area so that construction can continue on dry ground. A dewatering pump moves that accumulated water out faster than it flows back in.

Dewatering pumps are a type of submersible pump (or, where there is no mains power, an engine-driven surface pump) built for dirty water, suspended solids and continuous duty in harsh site conditions. This collection brings together the contractor pumps we supply most often for construction and site drainage.

Sizing tool

Water Pump Performance Calculator.

Indicative only This calculator uses a simplified parabolic pump curve and the Hazen-Williams friction loss formula. Real pump curves vary by model. Results are a guide only. Always verify against your pump's published performance data and consult our team if you are unsure.
How to use this calculator
  1. Enter your pump's max flow rate and max head from the datasheet or product listing. These are the peak figures at either end of the pump curve: max flow at zero head, max head at zero flow.
  2. Select your hose or pipe type. Suction and delivery hose is the most common for portable pumps. Layflat hose is used for longer water transfer runs. Rigid PVC pipe is for fixed installations.
  3. Choose the diameter to match your pump outlet or the hose you intend to use.
  4. Enter the total length of your hose or pipe run in metres from pump outlet to discharge point.
  5. For rigid pipe, add any 90 degree bends using the counter. Each bend adds resistance equivalent to extra pipe length.
  6. Read the results. The calculator estimates your duty point: the flow rate and head your pump will likely deliver through that hose run. For longest pump life, aim for a duty point in the mid-curve range (roughly 40 to 70% of max flow).
Step 1: Your pump specification

Labelled "max flow" or "free flow" on the datasheet: the flow at zero back pressure

Labelled "max head" or "total head": the maximum height the pump can push water at zero flow

Step 2: Your hose or pipe

Suction / delivery hose

PVC reinforced, helix coil, smooth bore: max 6 bar working pressure

Vertical rise from pump to outlet. Enter 0 if pumping on flat ground

Results
Friction loss per 10 m
–
m head / 10m
Total friction loss
–
metres head
Head remaining after friction
–
metres head
Estimated flow at duty point
–
L/min (indicative)
Buying guide

All about dewatering pumps.

What dewatering is, how to choose the right pump for the job, power options, and related site categories.

Choosing the Right Dewatering Pump for the Job

Construction sites involve more water tasks than most buyers realise. The fastest way to narrow the range is to start with the job.

Trench, foundation and excavation dewatering. The most common application. The EVAK Trenchman has a built-in agitator that keeps sand and silt in suspension where a standard pump would clog. The Tsurumi LB series is the industry-standard contractor pump and tolerates running with little or no water. For the highest flow rates, the APP HD-15 moves up to 830 litres per minute.

Sites without power. Early-stage and remote works often have no mains supply. Engine-driven pumps remove that dependency: the Honda WX and WB petrol pumps are popular with hire fleets, and the Drymax diesel trash pump handles sludge, mud and solids up to 40mm.

High flow and high head for major dewatering. For cofferdams, large excavations and watercourse diversion you need volume or pressure. See our high flow pumps and high head pumps.

Slurry and heavy solids. Concrete washout and piling slurry need a pump built for solids, such as the EVAK Agivort.

110V for Site Safety

Most UK construction sites require 110V equipment for safety reasons. Many of the pumps here are available in a 110V variant; see our dedicated 110V water pumps collection, and select the 110V option on the product page where it is offered.

Related Site Drainage Categories

Why Buy Dewatering Pumps from Flood & Water Pumps

We have supplied dewatering and construction pumps to UK contractors, hire fleets, housing developers and water companies since 2012. Our parent company Flood Protection Solutions Ltd is SSIP and CHAS accredited, and we hold the most popular contractor pumps in stock at our Nottingham warehouse for next working day delivery on orders placed before 2pm. To size a duty point, call our helpdesk on 0115 987 0358 or use the Water Pump Performance Calculator above.