How Do You Drain Water Out of a Newly Dug Hole/Trench?

Whether you’re digging a hole to lay a foundation for your patio or garage, or simply digging a trench to lay a new French or Trench draining system; chances are that as you water your lawn, water will drain into those trenches.

This could also be a result of permits being delayed and the monsoon season filling those trenches with water. When that happens, a question arises; how do you drain water out of a newly dug hole or trench? What can you do to continue working, or to ensure the water doesn’t present a threat?

There are a number of answers to this conundrum, including renting a high-powered sump (or other) pumps, digging deeper on one side and draining water from there, adding some gravel, and more. We’ll discuss these, along with some other solutions that you can adopt to drain water out of a newly dug hole or trench.

What If I Just Leave the Water There?

A partially flooded backyard during digging for extended patio pavers
A partially flooded backyard during digging for extended patio pavers

To understand what would happen if you were to leave water in a newly dug hole or trench, you will need to understand what happens in the ground around said trench. The soil around this trench is exposed to the elements and acts like a giant sponge.

Think of it like a tissue paper sitting on the table and you drop water on it. The water won’t just absorb where it comes into contact with the paper but will also spread within. Keep adding water and there will come a point when the tissue will start leaking water, dispersing it elsewhere.

Your newly dug trench or hole would do the same to your lawn. Whether it’s morning dew, watering your lawn, or rain, you’ll start to find water wherever you dig if you have an open trench filled with water.

Not only that, as your soil starts getting over-watered, if there is any point where the soil wasn’t compacted enough, water will start to pull it down with gravity. This will happen below the surface and therefore you won’t even know what’s going on until it’s too late.

The water will continue to seep through the soil and from days to months after it was absorbed, you will start seeing soft patches in your lawn or places where the grass will start dying. Worst case scenario, you’ll be dealing with a sinkhole(s) in your garden.

This also depends on the soil…

Depending on the soil type, the effect may actually be different for you. For example, if your soil has clay in it or is otherwise dense, the clay can expand when in contact with water. The expanded clay ends up blocking the water from moving into deeper sections of the earth and therefore forces it to spread sideways. This is known as your soil having a vertical profile.

Here, the soil changes with respect to the depth of your soil. For example, you have a very spongy and fertile topsoil that absorbs a lot of water and below it, you have soil with relatively larger grains and therefore end up draining all the water. Water can pass very quickly from here and move down.

Or the soil could be very dense and prevent water from travelling down.

Most soils also have a vertical profile that changes the deeper you go into the soil. The very spongy topsoil is the part that really absorbs water. However, below it, the soil becomes denser, and water can have a very hard time traveling through it if there’s a lot of clay.

To solve such a problem, you will have to create a gutter and downspout solution. Let’s discuss this in the next section.

How to Drain Water Out of a Newly Dug Hole or Trench – The Solutions

Using a Gutter

There is an age-old method which was first used by the Greeks to drain rainwater from rooftops; using a gutter and a downward slope – only, where they used to do that to their roofs, you’ll do the same in the trench or hole you’ve dug.

Start by creating a slope within the trench or hole. Expect to get your hands dirty here. Create a slope from every corner to one and then create a gutter that transports all the water to the lowest part of your land, i.e., where it would end up by default.

In case the hole you dug is too deep, you’re going to have to go with option two.

Rent a Pump

A sump pump from Amazon.com
A sump pump from Amazon.com

A traditional sump pump won’t do here; you’re going to need a heavy-duty pump that can kick out way more water than normal. Again, you’re going to have to dig deeper on one side to create a slope to route the water to one end. Dig a hole to collect all the water here.

Once you have water collected on one end, run a perimeter check to ensure all the water is headed into your hole and then start sucking the water up. It should take around 10 to 15 minutes for the hole to clear up.

Drain as much as you can with the pump and once clear, start adding gravel without leveling the area off until it’s time to close the trench/hole.

Scaping Mud & Dropping Gravel

If you’re in a hurry and the water isn’t that high, you can always consider dropping gravel on top of the water. Scape the mud around to create a firm layer of soil, compact it, and then drop gravel on top. This isn’t a very reliable solution, mind you.

The idea should be to firm up the bottom of the trench with clean gravel so that the water doesn’t stand still but, instead, continues seeping downward.

Call Public Authorities

If you can prove that the standing water is a threat to you or your neighbors, you can call public authorities to come and drain the water for you. Just remember to make sure you can’t be held liable for the trench, or else you might be subject to fines.

For example, a plumber left a trench open and their license expired, or they’re waiting for permits from the government, then you can call them. Either a fire truck or water tanker will come and use powerful pumps to drain water out.

Furthermore, by calling public authorities, you will also be able to get a better idea of whether it is safe to pump the water out or not.

If you live in a city, remember that these things can get quite complicated. Combined sewer systems usually don’t want additional water to flow into the system. Then there are some ‘construction site runoff’ lines that are deemed to be contaminated as well. If you drain water into these lines, chances are that you will be fined by the local authorities.  

Once you are done, you should consider adding a layer of concrete just to be sure that this doesn’t happen again. However, adjust the concrete pour according to your project.

About Charlie D Paige

Charlie is a massive DIY fan, with dozens of DIY projects under his belt - ranging from tiling to electrics, and concrete pads to walls. Charlie loves tinkering, seeing how things works, the outdoors and playing with power tools... so is it any wonder that he's completed so many DIY jobs over the years?

Charlie loves spreading his hard-won DIY experience with the world via this blog.