Case file — Alexandria, VA. One of the 25 jobs in our 250-home series. New here? Start with our open letter.
At a glance
| Location | Alexandria, VA |
| The problem | Water collecting against the foundation on a property with no lower ground to send it to |
| The fix | About 35 feet of exterior French drain and a catch basin, discharging to a sump pump with battery backup on its own electrical circuit |
| Extra visit | A return trip for the electrical work |
Every French drain is a slope
That is the whole idea. You dig a trench, you set a pipe in it at a fall, and water runs downhill through the pipe to somewhere it can safely leave.
Which means every French drain quote contains a silent assumption: that there is a downhill. Somewhere on the property lower than the trench, far enough from the house, where a few thousand gallons can come out without ending up in a neighbour’s yard or back against your own foundation.
On a lot of DMV properties there is not one. Flat lots, lots that fall toward the house, lots hemmed in by neighbours on both sides, lots where the only low point is the one you are trying to keep dry. When that is the case, gravity cannot finish the job and something has to lift the water instead.
What that changes about the job
About 35 feet of trench, lined with non-woven geotextile, a 4-inch perforated pipe set in it, gravel backfilled to grade. Standard so far.
A 12-inch catch basin, set in prepared excavation and connected to the pipe, collecting surface runoff into the same system instead of letting it sheet across the ground.
A sump pump with battery backup, rated to move about 3,900 gallons an hour at a ten-foot lift. This is the piece that replaces the missing downhill.
An electrical outlet and a dedicated line back to the panel.
That last item is why this case is in the series.
A pump is not a plumbing decision, it is an electrical one
This is the thing that surprises homeowners most, and it is the same lesson as the crawl space dehumidifier in our Southwest DC file: the equipment is the easy part. Getting power to it, correctly, is the part that takes planning.
A sump pump on a shared circuit is a sump pump that stops when something else on that circuit trips — and the moment it is most likely to happen is a storm, which is the moment the pump matters. So it gets a dedicated line: its own run, its own breaker, nothing else on it.
The battery backup is the second half of the same thought. Storms are also when the power goes out. A drainage system that only works while the grid is up is not a drainage system, it is a fair-weather convenience.
The return visit
Our records show a second, separate job at this property for the electrical work, some weeks after the drain went in.
That is normal and we would rather explain it than hide it. Electrical work has its own trade, its own scheduling and sometimes its own inspection, and forcing it to happen on the same day as trenching either delays the drain or rushes the wiring. Neither is a good trade.
What should never happen is the drain being finished, the pump being set, and the power question being left with the homeowner to sort out. That is how a correctly installed system ends up plugged into an extension cord.
If you are being quoted an exterior drain
Ask where the water comes out.
If the answer is a point on the property that is genuinely lower and genuinely far from the house, good — gravity is free and it never fails. If the answer is vague, or if the discharge is close to the foundation, then either the quote is missing a pump or the water is about to come straight back.