If you’re buying a home in Kentlands, Gaithersburg, there is a local property charge worth understanding before you finalize your ownership budget: the City of Gaithersburg Stormwater Program Fee.
The fee applies to developed properties within the City and is calculated according to the amount of impervious surface on the individual property. One billing unit represents 500 square feet of impervious area, and the City’s FY2027 rate is $32.28 per billing unit.
For buyers, the important point is that this isn’t simply one identical charge for every Gaithersburg home.
The property itself affects the calculation.
What Is Gaithersburg’s Stormwater Program Fee?
Gaithersburg uses the Stormwater Program Fee to fund its stormwater management responsibilities.
According to the City, the program supports work related to stormwater infrastructure, runoff management, water pollution requirements, flood control, erosion prevention, and Chesapeake Bay restoration obligations.
Every developed property within the City generates some amount of runoff and uses stormwater infrastructure, so developed properties are assessed through the program.
However, the amount is tied to impervious coverage rather than simply being identical for every parcel.
What Is an Impervious Surface?
An impervious surface is an area that prevents or substantially limits rainwater from soaking naturally into the ground.
Gaithersburg identifies several common residential features as billable impervious surfaces, including:
- Buildings and rooftops
- Driveways
- Parking areas
- Private sidewalks and walkways
- Private roads
- Patios
- Swimming pools.
One interesting distinction is that the City’s current guidance lists wooden decks as non-billable impervious surfaces for this fee.
That illustrates why buyers shouldn’t estimate the charge simply by looking at the total lot size.
How Does Gaithersburg Calculate the Fee?
For a single-account residential property, the City uses a relatively straightforward process.
First, it determines the total amount of impervious surface on the property.
Then it divides that amount by 500 square feet, which represents one billing unit.
The resulting number of units is rounded to the nearest whole billing unit and multiplied by the City’s current fee rate.
For FY2027, that rate is $32.28 for each impervious billing unit.
The actual charge therefore depends on the individual property.
Where Does the Stormwater Fee Appear?
Homeowners do not receive a completely separate annual City invoice for this charge.
Gaithersburg states that the Stormwater Program Fee is collected through the annual Montgomery County property tax bill.
It appears as:
GAITHERSBURG STORMWATER FEE
For buyers reviewing estimated property taxes and non-tax charges, this is one line worth recognizing.
Why Is This Relevant When Buying in Kentlands?
When comparing Kentlands homes, buyers naturally focus on the purchase price, financing, taxes, and association expenses.
But property-specific charges can also contribute to the annual ownership budget.
Two properties can have different amounts of impervious surface because of differences in their:
- Building footprint
- Driveway
- Patio
- Private walkways
- Other hard surfaces
That means buyers should check the actual property rather than assuming every Kentlands home carries an identical stormwater charge.
What About Condominiums?
Gaithersburg also has a calculation method for properties with multiple accounts, such as condominiums.
The City calculates the total impervious area for the property, determines the applicable total fee, and then divides that fee among the number of units or accounts associated with the parcel.
For condo buyers, this is another reason to review the actual property records and ownership structure rather than applying a single-family-home calculation.
Does Lot Size Determine the Fee?
Not directly.
A larger lot does not automatically mean a larger Stormwater Program Fee.
The important measurement is impervious surface, not total land area.
For example, grass and other surfaces that allow water to infiltrate are treated differently from rooftops, paved driveways, and patios.
A property with more land but less hard surface could therefore have a different calculation from a smaller parcel with more impervious coverage.
Can Buyers Look Up the Charge?
Yes.
The City provides a property lookup resource that allows property owners and buyers to review an estimate of the Stormwater Program Fee.
Gaithersburg also states that the actual fee appears on the property’s annual tax bill.
This gives buyers a way to research the individual property instead of relying on a general estimate.
What If the Impervious Area Looks Incorrect?
Gaithersburg maintains impervious-surface mapping and updates it periodically using aerial imagery and other information such as approved plans, as-built drawings, field surveys, and engineering tools.
If a property owner believes the calculated impervious area is incorrect, the City directs owners to contact City staff to discuss the property.
For a buyer, the practical approach is to identify the current charge and ask questions if something appears inconsistent with the property.
What Other Costs Should Kentlands Buyers Compare?
The stormwater charge should be viewed as one piece of a larger ownership budget.
When comparing properties, consider:
Mortgage Payment
Principal and interest based on your financing.
Property Taxes
Use property-specific estimates rather than generic ZIP-code assumptions.
Association Expenses
Review the applicable HOA or condominium assessments for the individual property.
Homeowners Insurance
Obtain a quote based on the actual home.
Stormwater Program Fee
Check the amount associated with the property.
Utilities
Consider the home’s systems, size, and available usage information.
Maintenance
Budget according to the property’s age, condition, and features.
This provides a much better comparison than looking at listing prices alone.
Could Future Property Improvements Matter?
Potentially.
Gaithersburg calculates the fee using the amount of impervious area on the property as of January 1 of each billing year.
The City periodically updates its impervious-surface data.
If you plan significant exterior improvements that create additional impervious area, it is worth understanding how those changes fit into the City’s stormwater system and any applicable permitting requirements.
Do not assume the property’s current fee will remain unchanged regardless of future improvements.
Why Does Gaithersburg Charge the Fee?
The City explains that impervious surfaces create runoff because rainfall cannot naturally infiltrate the ground.
That runoff enters the storm-drain system and can carry pollutants toward local waterways.
Revenue from the Stormwater Program Fee supports the infrastructure and regulatory work associated with managing that runoff.
For homeowners, it is essentially another property-specific cost connected to local infrastructure.
Frequently Asked Questions About Gaithersburg’s Stormwater Fee
How much is Gaithersburg’s Stormwater Program Fee?
For FY2027, Gaithersburg lists a rate of $32.28 per impervious billing unit. One billing unit equals 500 square feet of impervious surface.
Does every property pay exactly the same amount?
No. The charge is based on the amount of impervious surface associated with the individual property.
Does a driveway count?
Yes. Gaithersburg lists driveways as billable impervious surfaces.
Does a patio count?
Yes. Patios are included among the City’s billable impervious surfaces.
Where will I see the fee?
The fee appears on the annual Montgomery County property tax bill as the GAITHERSBURG STORMWATER FEE.
Work With Jeremy Rosenthal
Buying a home in Kentlands or elsewhere in Gaithersburg means looking beyond the asking price to understand the complete ownership picture. Jeremy Rosenthal is a REALTOR® serving Maryland, Virginia, and Washington, DC and helps buyers evaluate property-specific costs, transaction details, and available options before purchasing. Contact Jeremy if you’re considering a home in Gaithersburg or Montgomery County and want to better understand the property you’re evaluating.
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