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Glossary

Wet Well

What is Wet Well?

A wet well is the underground chamber in a pump or lift station that collects wastewater or stormwater before it is pumped onward; vacuum and combo trucks pump out accumulated sludge and grit for maintenance.

A wet well holds incoming flow at a lift or pump station until pumps move it to the next stage of the system. Solids, grease, and grit settle in the well and must be periodically removed to protect the pumps and maintain capacity.

Cleaning a wet well typically uses a vacuum truck or combination truck to suction sludge and liquid into the debris body, sometimes paired with sewer jetting to break up buildup. Rent wet well cleaning equipment through a free Vac4Rent request and rental companies reply directly.

Renting equipment for this job? Vacuum Trucks for Tank & Sump Cleaning

Guides that cover Wet Well

Related terms

Catch BasinCombination (Combo) TruckSludgeSewer Jetting

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Wet Well: common questions

What is Wet Well?+

A wet well is the underground chamber in a pump or lift station that collects wastewater or stormwater before it is pumped onward; vacuum and combo trucks pump out accumulated sludge and grit for maintenance.

Is a wet well considered a confined space?+

Wet wells are commonly classified as permit-required confined spaces under OSHA rules because they can contain hydrogen sulfide, methane, or oxygen-deficient air, and they have limited entry and exit. Entry typically requires atmospheric testing, ventilation, a permit, and rescue planning. Cleaning with a vacuum hose from the surface reduces or avoids the need for entry. Follow your employer's confined space program and OSHA requirements.

What is the difference between a wet well and a dry well at a pump station?+

In a dry-pit station, the pumps sit in a separate dry chamber next to the wet well and draw sewage from it through piping, so they can be serviced without entering the wet side. In a submersible station, the pumps sit inside the wet well itself and are lifted out on guide rails for service. Outside pump stations, "dry well" can also mean a gravel-filled pit that lets stormwater soak into the ground, which is a different structure.

How do you keep a lift station operating while the wet well is cleaned?+

Crews usually coordinate with the utility to schedule cleaning during low-flow periods and lock out the pumps before work begins. For longer jobs or high-flow stations, a temporary bypass pump may be set up to move incoming flow around the well. Procedures differ between utilities, so confirm the station owner's lockout, bypass, and notification requirements before the truck arrives.