A diesel pump is hired to move dirty water off a site and to keep running where there is no power to plug into. Weekly rates run about $250 to $900 depending on port size, and a two to six inch trash pump shifts somewhere between 200 and 1,500 gallons a minute. Size it on solids and head first, and only then on flow.
Port size is a starting point, not the answer
The inch figure on a pump names the hose it takes and hints at the flow, and yards quote it because buyers ask for it. What the pump actually delivers depends on how far and how high the water has to go. A four inch pump lifting twenty feet moves far less than the same pump discharging at grade.
Total head is what starves a pump
Add the vertical lift from the water to the pump, the lift from the pump to the discharge, and the friction in a long hose run. That total is what the curve is read against. Long flat runs of small hose cost more performance than people expect, so ask for the next size of hose rather than the next size of pump.
Trash, diaphragm or a wellpoint set
A trash pump passes solids and is the default for a flooded excavation. A diaphragm pump handles thick sludge and runs dry without damage, which suits a sump that empties. Groundwater coming through the walls rather than off the surface is a wellpoint or a sock job, and that is a different hire entirely.
Fuel, run time and pumping overnight
A dewatering pump often runs unattended for days, so tank size decides how often somebody visits. Ask for the run time at full load and whether the unit takes an auxiliary tank. Water standing in an excavation is a hazard that has to be controlled while people work in it, so the pump stopping is not a small problem.
Questions people ask about diesel pump rental
Diesel or electric for site dewatering?
Diesel where there is no supply, where the run is long, or where the pump has to move around with the work. Electric where a supply already exists and the noise matters, since a submersible in a sump is quieter and needs less attention. Many jobs end up with one of each.
How big a hose comes with the pump?
Suction and discharge hose are usually separate lines on the ticket, priced by the length, along with strainers and camlock fittings. Order the suction as short as the layout allows and the discharge as large as you can handle, because that is where the performance goes.
Where can the water be discharged?
That is a local question and it is worth asking before the pump arrives. Silty water off an excavation often cannot go straight into a storm drain or a watercourse without settling or filtration. A settlement tank or a filter bag is a cheap addition next to a stopped job.