Saltwater Intrusion & Salinity

Coastal and low-lying Sussex County wells face a concern most Delaware public-water customers never think about: saltwater intrusion.

Private wells

Short answer: A salty taste is not enough to diagnose saltwater intrusion. Test for chloride and salinity through a certified laboratory, and consider professional investigation if levels are elevated, since causes and solutions vary by well depth, construction, and location.

Why this matters in Delaware

Sussex County and other coastal areas face saltwater-intrusion risk from a combination of well construction, aquifer depth, tidal influence, flooding, and coastal development. Seasonal-use properties add another layer of complexity, since stagnant plumbing after periods of vacancy can also affect taste and water quality independent of salinity.

DNREC monitors coastal groundwater used by communities from Lewes to Fenwick Island and has also documented saltwater monitoring near North Bowers Beach and in the Potomac aquifer near the Delaware River in New Castle County. That means a salty result is a site-specific groundwater question in coastal Sussex, Kent, or parts of New Castle — not a diagnosis that can be made from a town name alone. A typical household water softener does not remove saltwater intrusion.

What can contribute to salinity concerns

Well depth and which aquifer it draws from
Proximity to tidal water or the coast
Flooding or storm-related inundation
Regional groundwater withdrawal patterns
Well construction and seal integrity

County and aquifer context

Coastal Sussex properties can draw from aquifers monitored by DNREC along the Atlantic coast, while Kent concerns may involve areas around Bowers Beach and North Bowers Beach. New Castle also has a long-running saltwater monitoring history in the Potomac aquifer near the Delaware River. These examples show why depth, pumping, tidal proximity, and well construction matter more than a generic “Delaware well-water” package.

The University of Delaware's Delaware Geological Survey RI86 study examines eastern Kent County's Columbia aquifer, including mixing zones near marshes and tidal streams and the possibility that irrigation pumping can shift the saltwater interface inland. DGS also reports that coastal Delaware's low elevation and shallow water table can make some aquifers sensitive to sea-level and saltwater changes. These are regional findings, not a prediction for an individual well.

Testing and treatment limits

Chloride, sodium, conductivity, and related chemistry can help establish whether a salty taste reflects dissolved salts. A softener is not a fix for saltwater intrusion. RO may improve one drinking tap, but whole-house salinity requires a professional review of the source, well construction, flow, waste stream, and long-term water supply. If flooding affected the well, follow DNREC or DPH guidance before returning it to normal use.

What to do

Test for chloride and salinity through a certified laboratory rather than relying on taste alone.
If elevated, consult a well professional about well depth, construction, and potential solutions.
For seasonal properties, flush the plumbing system after periods of vacancy before assuming a taste issue is salinity-related.
Retest periodically, since salinity can change with seasonal conditions, storms, and regional groundwater use.

Common mistakes

Diagnosing saltwater intrusion from taste alone
Assuming a seasonal property's stagnant-plumbing taste issue is the same as saltwater intrusion
Ignoring well construction and depth as contributing factors

What to document when salinity changes

Record the date, weather or flooding conditions, well-pump behavior, water level if available, and whether the taste is present in cold water, hot water, or only one fixture. A gradual change across the property is different from a hot-water-only odor or a single clogged faucet aerator. Compare chloride and sodium results over time rather than relying on taste intensity.

Do not abandon or alter a well without following Delaware requirements. A licensed well professional can evaluate casing, seals, depth, pumping rate, and nearby wells. Treatment may reduce exposure at a drinking tap, but it cannot restore a stressed aquifer or guarantee a whole-house supply.

Why a single salt-filter recommendation is risky

Chloride, sodium, conductivity, hardness, and total dissolved solids describe different aspects of the water. A softener exchanges hardness ions but is not a desalination plant. RO can reduce dissolved salts at a limited flow, while whole-house RO requires storage, reject-water handling, and careful maintenance. Match equipment to the measured result and intended fixture.

Because coastal properties may be seasonal, compare a baseline sample after the plumbing has been flushed with a sample collected during normal occupancy. A stagnant line can create a taste complaint, but it should not be used to dismiss a confirmed chloride trend.

Official sources

Does a salty taste always mean saltwater intrusion?

No. Taste alone is not a diagnosis. Other factors, including stagnant plumbing after vacancy or other mineral content, can also affect taste. Test for chloride and salinity to know your actual levels.

This page provides general educational information and is not a substitute for professional investigation of a specific property.

Last reviewed: 2026-07-11. Report a correction.