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Washington County, MD Landscaping Rules: Rainwater Harvesting (2026)

Light Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Governing law
SWM, Grading, Soil Erosion & Sediment Control Ordinance
Status
Approved ESD treatment practice, not mandatory
Design standard
County Design Manual & Public Works Standards
Tank check
Top elevation must be below the frost line
Enforcing agency
Division of Plan Review and Permitting

Summary

Washington County lists rainwater harvesting as an approved environmental site design (ESD) stormwater treatment practice for new development. Developers may use cisterns and storage tanks to meet county runoff-reduction requirements instead of building a pond or larger structural facility.

These county ordinances apply to unincorporated areas of Washington County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

b. The following ESD treatment practices shall be designed according to the Design Manual and the latest adopted version of the Washington County Standards and Specifications for Public Works Construction to satisfy the applicable minimum control requirements established in Section 3.5. and Section 3.6.2. of this Article: (a) Disconnection of rooftop runoff; (b) Disconnection of non-rooftop runoff; (c) Sheet flow to conservation areas; (d) Rainwater harvesting; (e) Submerged gravel wetlands; (f) Landscape infiltration; (g) Infiltration berms; (h) Dry wells; (i) Micro-bioretention; (j) Rain gardens; (k) Swales; (l) Enhanced filters; and (m) Any practices approved by the Director of DPRP and the Maryland Department of the Environment.

View official code

Full Breakdown

1). b). d). 15, Rainwater Harvesting inspection checklist). If a harvesting system is deeded to the county for public ownership and maintenance, the developer must also record the lot corners and follow the county's Policy on Construction of Infrastructure for Acceptance and Ownership (S-3) before conditional acceptance is granted. Rainwater harvesting is optional, not mandated: a project can meet its stormwater obligations through any qualifying combination of the listed ESD practices, so a builder who prefers rooftop disconnection or a rain garden instead faces no penalty for skipping harvesting altogether.

Violations & Fines

A stormwater management plan, including any rainwater harvesting component, must be approved by the Division of Plan Review and Permitting before a grading or building permit issues. Building without an approved SWM plan, or deviating from the approved design during construction, blocks issuance of the as-built certification and the use-and-occupancy permit, and can trigger a stop-work order from the Division until the nonconformance is corrected.

Frequently Asked Questions

Is rainwater harvesting required for new construction in Washington County, Maryland?
No. Section 3.6.1 lists it as one of thirteen approved ESD treatment practices a developer may choose from to meet stormwater runoff-reduction requirements. A project can satisfy the county's minimum control requirements using any qualifying combination of practices, so harvesting is an option rather than a mandate.
What does the county check on an underground rainwater harvesting tank?
During final grading, the Verifying Professional must confirm the top elevation of the underground storage tank is below the frost line, and must certify the tank's water tightness. Both checks happen before the county issues conditional acceptance under Section 3.15.
Can a rainwater harvesting system conflict with other Washington County rules?
No. Section 3.6.1.A.d requires every ESD planning technique and practice, including rainwater harvesting, to avoid conflicting with existing Maryland law or other Washington County ordinances, regulations or policies before the Division will approve it as part of a stormwater management plan.

Sources & Official References

Other rules in Washington County

Parking Rules: Street Parking LimitsSome RestrictionsParking Rules: RV & Boat ParkingSome RestrictionsTree Removal & Heritage TreesSome RestrictionsWeed OrdinancesSome RestrictionsParking Rules: Commercial & Oversized VehiclesSignificant RestrictionsParking Rules: Loading ZonesLight RestrictionsParking Rules: Abandoned VehiclesSome RestrictionsFence Regulations: Retaining WallsSome Restrictions

All Washington County rules

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