!A banner showing flooding in a house and two male neighbors arguing over a fence

When leaking or flooding water in and around houses causes widespread property damage—sodden basements, collapsing retaining walls, or soggy gardens, for example—serious disputes between neighbors can result. But the legal issues can be as muddy as the mess in your backyard. Here, we'll cover the legal issues and possible solutions concerning financial responsibility for damage caused by surface water in the United States, focusing on:

  • liability for damage caused by landscaping and similar work
  • liability for damage caused by the neighbor's carelessness, and
  • the amount of potential monetary liability.

In This Article

Who's Liable If Your Neighbor's Landscaping Causes Surface Water Runoff and Flooding?

As a broad rule, a neighbor is not liable for harm caused by the natural conditions of land. If the land lies in such a way that a particular amount of water is dumped onto your backyard every year from rain running off your next-door neighbor's property, it's not legally your neighbor's fault.

But what if your neighbor landscapes their property so that the amount of water running onto your yard doubles every year? Your neighbor would say that the change is still caused by the naturally occurring rain, not the landscaping. But you would probably prefer to take your neighbor's action into account. Three different rules of liability govern situations like this:

  • the "reasonableness" rule
  • the "common enemy" rule, and
  • the "civil law" rule.

The "Reasonableness" Rule (Applies in Most States)

In a majority of U.S. states, when one neighbor alters the land and damage occurs to another, that neighbor is liable for the damage if the alteration was "unreasonable." That means if you sue a neighbor over damage you've suffered, judges will want proof that the neighbor did something unreasonable, which altered the natural condition and caused your harm.

What is reasonable is decided by the courts on a case-by-case basis, by looking at factors such as:

  • the nature and importance of any improvements that the neighbor made
  • whether or not the damage was reasonably foreseeable to that neighbor, and
  • the extent of the damage compared to the value of any improvements.

The "Common Enemy" Rule: Lower Landowners Beware

In the past, many courts treated excessive rainwater as a "common enemy," which supposedly damaged property at random. Under this theory, you were expected to take measures to protect your own property from water coursing across the land. Even if one neighbor who lived on higher ground diverted water to prevent flooding and deposited it on your land, you were expected to protect yourself from it.

Fortunately for lower landowners, the handful of states that still follow some form the common enemy rule—Montana, New York, and the District of Columbia—have modified it. These states allow a property owner to divert vagrant surface water only if the work is not unusual or extraordinary and if the property owner uses reasonable care to avoid damaging adjoining property.

The "Civil Law" Rule: Upper Landowners Beware

A number of states follow a rule that is, in theory, the opposite of the common enemy rule. The civil law rule holds that a person who alters the natural flow of surface waters in any way that harms the use and enjoyment of another property will be liable for that harm. Unlike the common enemy rule, which requires lower landowners to fend for themselves, the civil law rule holds upper landowners liable for any detrimental changes in runoff patterns.

Like the common enemy rule, however, states no longer apply this rule in its strictest form. States have developed modifications and exceptions and often judge the behavior of both parties before saddling the upper landowner with the bill. California, for example, expects that both parties will act reasonably, which includes the duty of the lower landowner to take protective steps.

Is a Careless Neighbor Liable for Water Damage?

If your neighbor acts unreasonably or carelessly with water on their own property in a way that causes water damage to your property, you can sue for compensation for your losses and also ask the court to order the neighbor to stop the action.

Common culprits producing this type of water damage include garden hoses or sprinklers left running too long and water pipes that get clogged, get old, leak, crack, or freeze. Owners are responsible for their pipes and for damage they cause, even if the pipe just wears out or freezes in cold weather.

Tree roots, including roots from neighboring property, can also damage pipes. Just as property owners are responsible for damage caused by their broken pipes, tree owners can be held responsible for damage caused to another's property by their tree's branches or roots. (For more information, see Tree Disputes With Neighbors FAQs.)

What the Neighbor at Fault in Causing Water Damage Must Pay For

If a neighbor is legally responsible for water damage you suffer, you might be entitled to any or all of the following:

  • compensation for cost of repairs and replacements
  • compensation for your expenses, such as having to stay at a motel
  • reimbursement for your medical expenses
  • compensation for mental distress, if you have suffered an underlying physical injury
  • punitive damages, if a neighbor acted maliciously.

Civil court judges also frequently order problems to be fixed, if fixing them would be easy and inexpensive. Replacing a downspout, clearing away debris, or cleaning out a drain creates very little burden on a property owner. Judges are less likely to order someone to remove a retaining wall, re-landscape property, or redo a culvert.

Also realize that small claims court judges cannot issue orders such as these, only order that the offending party pay monetary damages.

When Homeowners' Insurance Covers Water Damage

Insurance in water damage cases is tricky. If the water comes into your home from an inside source—say, from a pipe in the townhouse next door—your ordinary homeowners' insurance should come into play. Contact your agent; your company may pay for your damage and then go after whoever caused it for repayment.

However, when the damage comes from outside rising water, you may need flood insurance, even if your neighbor's action caused the problem. If the problem was caused at least in part by a neighbor, your neighbor's company might well pay you directly. The neighbor's insurance company might also tell your neighbor to correct the problem—or risk cancellation of the insurance policy.

Next Steps

If you still have questions about water damage and your rights against a neighbor, check out Neighbor Law: Fences, Trees, Boundaries & Noise, by the Editors of Nolo, or consult an experienced real estate lawyer. The attorney might be able to help you bring a lawsuit. In preparation for such an event, gather documentation of the damage: photos, contractor's estimates for repairs, witness statements, and so on.