Standing Water & Drainage

The situation

Part of your yard stays wet for days after rain. The grass is thin or dead, the ground is spongy, and there may be a smell. In heavy summer rain it turns into a genuine puddle.

This is close to universal in South Florida, and it is not your fault. The water table here sits very close to the surface, and a lot of yards were graded to shed water toward somewhere that no longer drains.

What to buy

The standard fix is a French drain: a trench, a perforated pipe, and rock around it. Water takes the easy route — through the rock instead of sitting in the soil — and runs to somewhere you have chosen.

The rock is #57 rock, and the reason is specific. It is washed, so the dust and fines have been rinsed out. That leaves roughly a third of its volume as open space between the stones. Water moves through it freely.

Do not use crusher run, screenings, road base or anything described as compactable. Those contain fines on purpose — that is what makes them lock up — and in a drain those fines silt up the gaps and the drain stops working within a year or two.

The other thing that matters is landscape fabric. Line the trench with it before the rock goes in and fold it over the top. Without it, soil washes into the rock from the sides and clogs it. Fabric is cheap. Digging the drain out again is not.

How much you need

A typical residential French drain is about 12 inches wide and 18 to 24 inches deep.

At 12 inches wide and 18 deep, you need roughly 1 cubic yard for every 18 feet of trench. So:

• A 30-foot run — about 2 yards
• A 50-foot run — about 3 yards
• A 100-foot run — about 6 yards

No compaction allowance here — #57 does not compact, which is the point.

If you are also fixing a low spot rather than just draining it, you may want fill dirt to raise the grade and topsoil to re-seed over it.

Not sure? Tell us the rough size of the area and how deep you want it and we will work it out with you. Nobody expects you to know this — it is our job, not yours. Or use the calculator.

How to do it

1. Work out where the water will go. A drain has to end somewhere lower — a swale, a street edge, a dry well. This is the step people skip, and a drain that runs nowhere just moves the puddle.
2. Dig the trench with a fall along its length. Even a slight slope. Water will not run uphill.
3. Line it with landscape fabric, leaving plenty of overhang on both sides.
4. A few inches of rock, then the perforated pipe, holes facing down.
5. Fill with rock to within a few inches of the surface.
6. Fold the fabric over the top, then cover with soil and sod, or leave the rock exposed as a decorative dry creek.

Materials for this job

Standing Water & Drainage — common questions

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