Serving Portsmouth
Groundwater & Basement Water Intrusion in Portsmouth, NH
Basement seepage, failed sumps, and hydrostatic pressure against the foundation are extracted and dried, and the path from the ground is identified so the loss does not repeat. Groundwater and basement seepage are extracted and dried only after the path from the soil is identified — a wall, a slab, a drain, or a failed sump. Drying the interior without stopping that path returns the same water to the same floor.
Frequently asked questions
The low streets flood on a storm tide with no rain.
That is coastal flooding rather than a drainage fault, and it is worth distinguishing because the responses differ. A surge on top of an already high tide raises the river above the level of the low streets, and the drainage that normally discharges there is under water. Nothing is blocked. The astronomical tide combined with the surge forecast predicts it far better than any rainfall figure.
Can an eighteenth century cellar be kept dry?
Manageably damp is the honest target. A stone or rubble wall has no continuous surface to seal, and coatings applied inside tend to move water rather than stop it, sometimes into the mortar higher up. What works is managing water before it reaches the wall with grading and roof drainage, then handling what still arrives with an interior drain and a sump. Expecting a finished dry room out of that space is what leads to expensive disappointment.
Is there anything specific about historic materials after a flood?
Yes, and it argues for slower drying rather than faster. Old plaster, lime mortar, and original woodwork can be damaged by aggressive drying as much as by the water, and replacing them is rarely straightforward. A contractor experienced with historic fabric will use gentler drying over a longer schedule and will know what can be saved. It is worth asking about that experience specifically before work starts in the core.
The Portsmouth overview carries this FAQ with the city research.