Can a Neighbor Drain Water Onto Your Property in Pennsylvania?

In Pennsylvania, a neighbor may allow surface water to flow onto your property along its natural course, but they cannot lawfully collect, concentrate, or redirect that water onto your land in increased volume or force. This is the “common enemy rule.” When an upper landowner artificially alters the natural flow and causes damage, they may be liable to the lower landowner.

Understanding how stormwater and surface water drainage work between neighboring properties is essential for any Pennsylvania landowner, particularly as development, redevelopment, and heavier storms change how water moves across the land.*

What Is the Common Enemy Rule in Pennsylvania?

The common enemy rule is the Pennsylvania doctrine governing surface water between neighboring properties. It gives an upper landowner the right to discharge surface water onto lower land along its natural course, quantity, and concentration, and it requires the lower landowner to accept that natural flow. The right is not unlimited.

Pennsylvania common law has long recognized the right of an upper landowner to discharge onto the land of another surface waters flowing on or over the owner’s land through a natural water course. Since the mid-1800s, the Pennsylvania Supreme Court has held that, essentially, because water flows downward, the owner of the upper land has an easement over the land of the lower owner to discharge all water that may flow or fall upon the upper lot.

But the right of an upper landowner to discharge water on the lower land of his neighbor is not unlimited. Generally, this right to discharge is only for the water’s natural courses, quantities, and concentrations. Of course, the lower landowner must accept the water lawfully discharged by the upper landowner. This concept is broadly known as the “common enemy rule.”

When Is a Neighbor Liable for Water Runoff? Exceptions to the Right of Discharge

A Pennsylvania neighbor may be liable for water runoff when they either divert water from its natural channel by artificial means, or unreasonably or unnecessarily increase the quantity or change the quality of water discharged onto adjoining land. A lower landowner generally must prove one of these two exceptions to establish liability.

The right to discharge is not unlimited. To establish liability for unlawful discharge, a plaintiff need only show that a landowner collected and/or concentrated surface water from its natural channel through an artificial medium and discharged the water onto the plaintiff’s property in an increased volume or force, however slight.

An upper landowner’s right of flowage is generally subject to two exceptions.

First, the upper landowner may not “alter the natural flow” through concentration, even if the water ultimately discharged is no greater in quantity. As an example, an upper landowner’s construction of a series of pipes or ditches collecting quantities of water to a point of discharge upon the lower landowner’s land exceeds the rights of the upper landowner.

Second, the upper landowner may not “unreasonably or unnecessarily” change the quality or quantity of the water discharged on the lower land. As an example, land development that redirects, concentrates, or changes the water flowing onto lower land could cause liability to the upper landowner. This potential liability is of course balanced by reasonable development of the land in accordance with municipal and state regulations.

To impose liability on an upper landowner for the effects of surface water runoff on a lower-lying property, the lower landowner must generally show one of these two exceptions applies, that the upper landowner either “diverted the water from its natural channel by artificial means, or . . . unreasonably or unnecessarily increased the quantity (or changed the quality) of water discharged upon his neighbor.”

When Is an Upper Landowner NOT Liable? Limited Exceptions to Liability

Even where it is proven that the upper landowner has changed the land such that a change of the natural flow of the water occurs, or concentrates the water at a particular point, or increases the water’s volume, the upper landowner may avoid liability if it is shown that the use that inflicted the damage was “natural, proper, and free from negligence, and the damage unavoidable.”

It is a long-recognized principle that all landowners have a right to the use and enjoyment of their own property, and if in exercising that right, without negligence, an unavoidable loss occurs to the lower landowner, then the law will treat this as a “loss without injury.” For this liability exception to apply, the upper landowner must show that “the damage was necessary and unavoidable” and that it could not be prevented by reasonable care.

The Pennsylvania Stormwater Management Act

Many municipalities have adopted stormwater ordinances or other applicable regulations. Additionally, the Commonwealth of Pennsylvania enacted the Stormwater Management Act (“Act”). The Act does not change or supersede the common law rights, obligations and remedies as between an upper and lower landowner, nor is the common enemy rule impacted. Pertinent to a general understanding of stormwater law in Pennsylvania, as between landowners, the Act provides:

Any landowner and any person engaged in the alteration or development of land which may affect stormwater runoff characteristics shall implement such measures consistent with the provisions of the applicable watershed stormwater plan as are reasonably necessary to prevent injury to health, safety or other property. Such measures shall include such actions as are required:

(1) to assure that the maximum rate of stormwater runoff is no greater after development than prior to development activities; or

(2) to manage the quantity, velocity and direction of resulting stormwater runoff in a manner which otherwise adequately protects health and property from possible injury.

Stormwater Management Act, 32 P.S. § 680.13. However, subsequent case law has held that neither landowners nor state and local governmental entities could be held liable under the Act for flooding incidents impacting other property owners that occurred before the county adopted its watershed stormwater plan, because a prerequisite for a violation of the Act was the existence of such a plan. See Lincoln Investors, L.P. v. King, 152 A.3d 382 (Pa. Commw. Ct. 2016). Certain political subdivisions may also be liable under the Act.

Conclusion

Stormwater remains the “common enemy” among landowners. As land development overtakes natural open space, and suburban sprawl and redevelopment changes the natural, or existing, flow, course and concentration of water, stormwater rights, remedies and regulation have become increasingly utilized.

Further, with what appears to be an increase in drastic rain and storm events, stormwater runoff is amplified and so are its effects and potential damage. Reconfigured roadways and private drives, railroads, damaged creeks and detention basins have all been the subject of litigation, in addition to claims arising simply from the development of raw land, or the redevelopment of an existing site with unplanned, or under-planned, stormwater results.

Flooding the land of another with increased flow, or collected, re-channeled water, is prohibited. Likewise, also prohibited is a lower landowner damming, or blocking, acceptance of a permitted flow of water from an upper landowner.

Talk to a Pennsylvania Stormwater and Drainage Attorney

If you are dealing with flooding, runoff from a neighboring property, drainage disputes, or development-related stormwater, the facts of how the water moves and what changed are critical. Eric B. Smith, Esquire, Chair of the Litigation Group at Timoney Knox, LLP in Fort Washington, Pennsylvania, represents property owners in stormwater, drainage, and real estate disputes throughout the Commonwealth.

Call 215-540-2653 or email esmith@timoneyknox.com to discuss your situation.

*This article does not address the breach, alteration, or enforcement of express or implied stormwater easements.

Frequently Asked Questions

Who is responsible for water drainage on my property in Pennsylvania? As a general rule, a lower landowner must accept surface water that flows naturally onto their property from higher ground. However, a neighbor is responsible, and may be liable, when they artificially collect, concentrate, or redirect water onto your land in increased volume or force. Responsibility turns on whether the natural flow was unlawfully altered.

Can I sue my neighbor for water runoff in Pennsylvania? You may have a claim if your neighbor diverted water from its natural channel by artificial means, or unreasonably increased the quantity or changed the quality of water discharged onto your property. Remedies can include damages and injunctive relief requiring the neighbor to correct the condition. Because these cases are fact-intensive, legal review is important.

What legal options do I have if my property floods due to a neighbor’s construction project? If a neighbor’s construction project alters the natural water flow, concentrates runoff, or increases water discharge onto your property, you may have a claim for damages or injunctive relief. Timoney Knox can evaluate your case and help protect your property.

Can I be held liable for stormwater runoff if I comply with local development regulations? Even if you comply with municipal and state regulations, you could still face liability if your actions unreasonably alter the natural flow or concentration of water, causing harm to neighboring properties. Timoney Knox can help assess and mitigate risks.

May my neighbor redirect stormwater onto my property? No. An upper landowner may not collect, concentrate, or redirect stormwater onto lower land beyond its natural flow, course, and concentration.

May my neighbor build a dam or otherwise block the flow of stormwater from my property onto theirs? No. Just as you cannot concentrate and redirect stormwater onto your neighbor’s property, your neighbor cannot block or dam your stormwater from its natural flow onto their land.

My neighbor regraded his lot so that his stormwater now flows onto my property. What can I do? A neighbor may not alter the natural flow or direction of stormwater. He may be required to correct the grading and may be liable for resulting damages.

The Township approved tree removal and grading on my neighbor’s lot, concentrating stormwater onto my property. Is my neighbor protected because the Township permitted it? No. Even if the Township permitted and approved the plans and work, your neighbor may not cause stormwater to be concentrated and directed onto your property.

About The Author(s):

Eric B. Smith

Mr. Smith, a partner of Timoney Knox, LLP, serves as Chair of the Firm’s Litigation Group and has been consistently recognized by Super Lawyers and Best Attorneys since 2005.  In 2017 Mr. Smith served as the President of the Montgomery Bar Association.  His commercial and real estate litigation practice spans across the Commonwealth of Pennsylvania.

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