What Is the Purpose of a Sump in a Trench?

Mitchell Brock

A sump is a water container reservoir that sets below the bottom of a trench. A trench is an excavation that is narrow compared to its length. Sumps were installed in the trenches dug for World War I and World War II. The sump has a specific purpose when placed in a trench.

A long trench being dug by a backhoe.


The main purpose of a sump in a trench is to drain the water that collects at the bottom of a trench. The water will run off the bottom of the trench and into a sump pit or reservoir so the bottom of the trench can remain relatively dry and not hold water. The installation of a sump in a trench is required if the trench remains open for a long period of time.

Sump Installation

A sump is generally installed along each side of the bottom of the trench. A small reservoir is dug and sloped in one direction so it can run the water to a sump pit. The sump pit is a larger collection area, dug deep below the bottom of the trench to collect all the water running through the sump reservoir. The longer the trench, the more sump pits required. The sump pits will be strategically located so they can collect the water without overflowing.

Water Removal

Once the water runs into a sump pit, a sump pump is generally used to remove the collected water. The pump sucks out the water and pushes it through a hose or pipes, relocating the water away from the trench. A lot of farmers use trenches and sump pits throughout their farmland to collect water so it can be used to water the fields when droughts conditions occur.


Many states have regulations regarding trenches and sump waste disposal. Both Nebraska and Massachusetts have published rules regarding trenches and sumps. The Massachusetts Public Safety division defines as a trench as being an excavation more than 3 feet deep, and these trenches require certain safety procedures. Nebraska Department of Environmental Quality describes the procedures that must be followed when disposing of sump waste. Besides collecting water, sumps can collect debris and waste from the bottom of trenches. The waste and debris that collect in the sump pit must be tested to ensure it is not hazardous waste.