A dry well that overflows or stays full has one of three problems: it has filled with silt and debris, it is too small for the water sent to it, or it sits in soil or groundwater that cannot take the water away. The first can often be fixed by cleaning it out and adding a way to catch the dirt before it gets in. The other two cannot be cleaned away, and pretending otherwise is how people pay for the same dry well twice.
What a dry well actually is
A dry well collects nothing. It is a destination: a structure in the ground that holds water long enough for it to soak into the surrounding soil. It is what you build when collected water has nowhere else to go, meaning no lower ground to daylight to and no street or storm system the town will let you use. We laid out where it sits among the options in French drain, catch basin or dry well.
That also means a dry well is only ever as good as two things: the soil around it, and how clean the water is that goes into it.
Why dry wells fail
- Silt and debris. Roof water carries grit and leaves, and surface water carries soil. Without anything to stop it, that settles in the bottom and coats the sides, and the soil stops accepting water. This is the most common failure and the most fixable one.
- Too small. A dry well is sized to the volume it has to hold in a storm. One sized for a single downspout that later gets a second roof, a driveway or a sump line tied into it will fill and overflow in any real rain.
- The wrong soil. Tight clay or dense glacial till drains slowly, and no structure changes that. A dry well that was never going to drain in that ground fails from the first season.
- High groundwater. If the water table comes up near the bottom of the well in the wet months, the well is sitting in water. It fills from below and has nowhere to empty to until the table drops.
How to tell which one you have
Look at when it fails. Overflowing only in heavy storms, and emptying within a day or so afterward, points at size. Draining more slowly every year points at silt. Full in spring and fine in late summer points at groundwater. Never draining at all from the start points at the soil. A look inside, when the well has an access lid, usually settles it.
Can a dry well be fixed?
A silted dry well often can. It gets pumped and cleaned out, and the inlet gets something to stop it happening again: a catch basin with a sump, a sediment trap or a basket that holds the debris where it can be emptied instead of letting it reach the well. Gutter guards upstream help too. A dry well that is too small can sometimes be helped with added capacity alongside it.
A dry well in the wrong soil or below the water table cannot be fixed by cleaning. The honest options are sending some of the water elsewhere, moving the well to better ground, or rethinking the drainage so less water needs to be disposed of in the first place, which often starts with the grading.
Are dry wells legal in New Jersey?
They are a normal, accepted way to dispose of clean roof and yard water on a residential lot. What they may never take is sewage or anything from the sanitary side, and a dry well that overflows onto a neighbor's property or a road becomes a problem in its own right. Whether your town wants to see a plan for one is a question for its construction or engineering office.
What it costs
New concrete seepage tanks are the expensive end of residential drainage, and we publish our range rather than hiding it: see what our work costs. That price is exactly why it is worth trying the cheaper fixes first: regrading and downspout work, a catch basin that keeps the dirt out, or getting the roof water somewhere it can daylight.
If the well is on karst ground in Sussex or Warren, be careful about concentrating a lot of water in one spot at all, for the reasons in sinkholes in Sussex County.
Diagnosing a failed dry well, and building the replacement or the alternative, is our grading and drainage work.
Common questions
Why is my dry well overflowing? Usually one of three things: it has filled with silt, it is too small for the water sent to it, or it sits in soil or groundwater that cannot take the water away.
Can a clogged dry well be fixed? A silted one often can: pump and clean it, then add a sediment trap or catch basin at the inlet so the debris is caught before it reaches the well.
Can a dry well be fixed if the soil will not drain? Not by cleaning. The options are moving it to better ground, sending some of the water elsewhere, or reducing how much water needs disposing of, often through grading.
Are dry wells legal in New Jersey? They are a normal way to dispose of clean roof and yard water on a residential lot. They may never take sewage, and your town may want to review one.
How do I know if my dry well is too small? It overflows in heavy storms but empties within a day or so afterward. A well that drains more slowly every year is more likely silting up.
Still not sure how this applies to your property? That is what a free on-site estimate is for. Call 862-268-2510 or tell us what is going on, and we will give you a straight answer, including when the answer is that you do not need us.