Drainage Guide

SWALE, CULVERT
OR REGRADING?

All three can move water. They do it in different ways. A swale creates a route across the surface. A culvert carries water beneath an access route. Regrading changes the shape of the land so runoff naturally travels in a better direction. The right solution depends on where the water comes from and what is in its way.

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Use a swale when surface
water needs a path

A swale works with the surface grade.

It can collect or intercept runoff and guide it through a deliberate low area rather than allowing the water to spread across a yard or create its own erosion channel.

The important question is not only where the swale starts.

It is where the water can safely go after traveling through it.

Use a culvert when water
needs to cross under access

Driveways and private roads often interrupt natural drainage.

When water needs to move from one side of the access route to the other, a culvert can provide that crossing without sending runoff across the driving surface.

The surrounding ditch, inlet and outlet still matter because the pipe only handles the portion of the drainage path that passes beneath the access.

Use regrading when the land itself
is sending water the wrong way

Sometimes there is no missing drain.

The grade is simply wrong for what the property needs.

A low area may collect runoff. A slope may send water toward a structure. A driveway may be shaped in a way that encourages water to follow it downhill.

Regrading changes the land so gravity begins helping instead of hurting.

When more than one
solution is needed

A common drainage project can involve multiple parts.

For example:

A graded ditch may collect water beside a driveway.

A culvert may carry that water beneath the driveway.

The outlet area may then need additional grading so the discharged water continues away without creating erosion.

The systems work together.

Do not start with the product.

Homeowners often call asking for a culvert, ditch or drain because that is the solution they already know.

A better starting point is:

Where does the water begin?

Where does it travel?

What is it damaging?

Where can it safely go?

Once those questions are answered, the correct tool becomes much clearer.

Quick decision guide

Swale or Ditch

Surface runoff needs a defined path along the property.

Culvert

Water needs to cross beneath a driveway or access route.

Regrading

The existing shape of the property is directing water poorly.

Combination

The water path crosses multiple parts of the property and one method alone cannot complete the route.

Common questions

Is a culvert better than a drainage swale?

They solve different parts of a drainage problem. A swale carries surface runoff along the ground, while a culvert carries water beneath access.

Can regrading replace a drainage system?

Sometimes changing the grade is enough to improve surface drainage. Other properties still need defined drainage routes or crossings.

Why does water keep returning after drainage work?

A drainage feature can fail to solve the problem when the larger water path was not addressed. The inlet, route and outlet all need to work together.

Not sure what drainage
fix you need?

You do not need to diagnose the property before calling. Tell ELMS what the water is doing.

Let's get your project
done the right way.

Reach out — we'll review your project and walk you through the next step.