Site Drainage: How It Works and How to Hire

What does a drainage contractor actually do?

A drainage contractor works out where water is entering your property, where it is collecting, and where it can legally go — then builds the shortest path between those points.

Most of the value is in the first half of that sentence. Installing pipe is a day's work for a competent crew. Deciding which pipe, at what depth, on what slope, discharging where, is the part that determines whether the job still works in five years.

The trade sits next to two others that overlap it. Grading contractors reshape ground. Waterproofing contractors treat the building. A drainage contractor works the ground in order to protect the building, which is why the good ones start by measuring the ground rather than by describing a product.

How much does drainage work cost?

It ranges across roughly a tenfold spread, because "drainage" covers everything from a $40 downspout extension to an interior perimeter system with a pump.

Every figure, including what is in a per-foot price and what is always extra, sits on the french drain cost guide — which also separates the four different jobs that all get quoted as a "french drain," and covers permit fees and outlet costs.

How does a drainage contractor assess a site?

In a fixed order, because each step decides the next. A contractor who skips to step four has guessed at steps one through three. This sequence is the single most useful thing on this page, because it lets you evaluate the assessment rather than the quote.

1. Where is the water coming from?

Not where it is sitting — where it originates. There are only three answers, and they map onto three different solution families:

• Surface grade directing water toward the house or into a low spot instead of away from it.
• Concentrated roof water — downspouts discharging at the foundation, or somewhere with no path to daylight.
• A subsurface condition — clay-heavy soil, a hardpan layer, or a high seasonal water table preventing infiltration.

That framing comes from the drainage firm Joyce|Cline, and it is the cleanest published version we found. Identifying which one drives the problem determines the correct solution. Everything after this step is downstream of getting it right.

Our guide to what a french drain is and what it treats carries the homeowner version of the same test — whether the water appears during rain, after rain, or always.

2. Does the grade meet code at the foundation?

This is the measurement that separates an assessment from a sales visit, and it has a number attached.

Then read what the code says next, because it is the whole argument of this page: "Where lot lines, walls, slopes or other physical barriers prohibit 6 inches of fall within 10 feet, drains or swales shall be constructed to ensure drainage away from the structure."

Drains are what the code asks for when grading is impossible. They are not an alternative you choose because they sound more thorough. A drain installed on ground still sloping toward the house inherits a load it was never sized for — and correcting the grade afterwards means paying twice.

3. What will the soil actually absorb?

Soil texture and infiltration rate decide whether half the solution set is available to you at all. A dry well needs soil that accepts water. A french drain in tight clay is collecting from a much smaller catchment than the same trench in loam.

This is the same soil science that governs a septic drain field, which is a useful thing to know if you are buying rural land: one soil evaluation answers both questions. Our perc test guide explains how a soil evaluator measures infiltration rate and the seasonal high water table, and what the numbers mean.

4. Where can the water legally go?

Find the outlet before designing anything. This is the step that kills more projects than any other, because every solution except a dry well needs somewhere lower to discharge to — and "lower" has to be legal as well as physical.

If there is no daylight outlet, the solution set changes completely: a dry well or a pumped system, not a gravity drain. And where the water lands matters. Texas puts it in statute — Water Code §11.086 makes diverting surface water onto a neighbor actionable — which is covered in full on the cost guide, alongside street and storm-system connections.

5. What is already in the ground?

Plenty of properties already have drainage that stopped working, and the previous owner never mentioned it. A contractor should trace an existing system from inlet to outlet before proposing to replace it — a camera inspection will show whether a buried outlet line is healthy or crushed.

The failure mode this prevents is expensive and common: a new system built around a hidden blockage that was the actual cause all along.

Two things to have ready before they arrive

Both are free, and both make you a better client than most:

• Film the yard during the next heavy rain. Storm footage shows how water actually behaves on your property, which no dry-day site visit can reproduce. The drainage firm DrainDesigns asks for it specifically.
• Run a garden hose where you think the water goes. It is a crude visualization and it is remarkably good at proving you wrong about the direction of a slope.

Grading, french drain, dry well, catch basin or sump pump?

Trade articles write these up as competitors. They are not — they are components with different jobs, and real systems routinely combine two or three. What actually decides selection is what each one requires to function.

Read the table by elimination rather than by preference. No fall available and no daylight outlet rules out three of the five immediately. Dense clay rules out the dry well. No power at the discharge point rules out the pump.

On the pump, the trade rule is worth repeating because it is right: gravity does not break down. A gravity system keeps working in a power cut and costs nothing to run. A pump is the correct answer when water sits below the outlet elevation — and the wrong answer whenever slope would have done the job.

Note what the table does not separate: swales, curtain drains, french drains and trench drains are four different jobs that all get quoted as a "french drain," and telling them apart is what stops you comparing two incomparable bids. That breakdown is on the cost guide.

How urgent is a drainage problem?

Less urgent than a septic failure, and worth being honest about that. Drainage problems rarely need a call tonight. What they do is progress — and standing water, a wet basement and a cracking foundation are usually the same problem observed at three stages rather than three different problems.

The third row carries the point people least expect: fixing the drainage stops the cause but does not repair the effect. At that stage a drainage contractor is no longer the only professional you need, and any contractor who says otherwise is selling outside their competence.

Is drainage work licensed?

There is no drainage contractor license. Not in any state we checked. Each state folds drainage into whichever general contractor or landscaping rule it already has — and our three launch states answer it three completely different ways.

Texas — no state license for the work itself

Texas issues no state landscaping or drainage contractor license. A residential drainage job is generally governed by local permits rather than a state credential.

One credential does exist, and people confuse it for a drainage one: TCEQ licenses irrigation. A person may not sell, design, install, maintain, alter, repair, service or inspect an irrigation system in Texas unless licensed as a Landscape Irrigator, or working as a registered Irrigation Technician under one. If your job touches sprinklers, that license is a real requirement — the drainage half of the same job is not.

Verify: TCEQ landscape irrigator licensing

Florida — drainage ditches are written out of the contracting chapter

Florida is explicit, and the exemption is easy to miss. F.S. 489.103(10)(a) exempts "any construction or operation incidental to the construction or repair of irrigation and drainage ditches" from the state construction contracting chapter entirely.

That does not make the work unregulated. It moves the regulation to the county and the water management district, where stormwater and discharge rules sit. Ask about the permit, not the license.

Verify: Florida Statutes §489.103, exemptions

North Carolina — a real license, above a real threshold

North Carolina is the strict one of the three. The NC Landscape Contractors' Licensing Board licenses landscape contracting under G.S. Chapter 89D, and the licensed scope covers finish grading, preparation of plots and areas of land, and landscape drainage systems.

Several groups are exempt regardless of price, including licensed general contractors, professional engineers, landscape architects, and property owners working on their own property. Erosion control is separately exempted.

Verify: NC Landscape Contractors' Licensing Board — licensing and exemptions

The requirement that applies everywhere: call 811

This one is not optional, not waived by scale, and applies to a homeowner with a shovel exactly as it applies to a crew with an excavator. It is also a scheduling fact, because the notice window is a wait:

Basis: state statutes and the state notification centers, read 2026-08-07. Confirm the current window with your own 811 center before scheduling — dial 811, or use Sunshine 811 in Florida and NC811 in North Carolina. Subaqueous work carries much longer windows in both states.

Use it as a competence signal as well as a legal one. A contractor who proposes to dig tomorrow has not filed the ticket.

How to choose a drainage contractor

Because the licensing answer is often "none required," the useful checks are different from the ones that work in a licensed trade. Four things carry the weight:

• Ask what they measured. The fall at the foundation, the soil, the outlet elevation, the existing system. A contractor who quotes without measuring the grade has priced a product, not solved a problem. This is the highest-signal question on the list.
• Ask about the permit, not the license. Grading, excavation and stormwater permits are far more universally required than any license, and they carry lead times.
• Ask for the certificate of insurance — general liability, direct from the insurer, current. Where licensing is absent this is the real backstop, and a serious contractor produces it without a reminder.
• Ask when they filed the 811 ticket. Legally required, universally applicable, and instantly revealing.

Get written scope on all four points before you compare prices. Two drainage bids for different scopes are not comparable, and drainage is a trade where the difference hides underground.