At common law, anything done to the bed of a river which produces no sensible (appreciable) effect on the watercourse is permissible. However, this is subject to requirements under planning, environmental and fisheries legislation in many cases. It is not enough that it is permissible at common law.

Riparian owners are not entitled to use the bed in such manner as to limit the  natural flow of the watercourse or interfere with its natural course. At common law the construction of an embankment which narrowed the watercourse but did not obstruct it  did not give rise to a claim in damages. Similarly, in other cases it was held that placing stakes on the soil of the river to prevent erosion or floods or to make pens to prevent cattle from straying, was permissible where did not affect the rights of other owners.

An obstruction cannot be built on a watercourse such as to throw back water onto an upper riparian owner’s land causing flooding. In an action for obstruction, it is not necessary to prove actual loss of damage. The erection of an illegitimate obstruction gives rise to a right of injunction.

The position can change over time. The entitlement is  to have preserved  the natural and apparently permanent course existing when the right is asserted and called into question. The riparian owner cannot remove a long established natural accretion of gravel or shoal in a riverbed so as to restore the flow of water to its former state at some earlier time  as to velocity direction and height.

The riparian owner may not alter the level of the river by removing obstructions which by lapse of time become embedded and consolidated and form part of the riverbed if the effect of so doing is to diminish or increase the flow of water which the owner lower down has been enjoying owing to the diversion of the water or the alteration of the level by the obstruction. This may be the subject of remedial action under legislation.

There exist common law rules relating to abatement of nuisance which allows self-help to some limited extent. However, self-help remedies are not favoured by the courts and their is is not advisable


The converse of the right to water flow is the right of drainage.  This is the right to allow water to flow from one’s land away.

At common law an owner has a right to drain his  land for agricultural purposes to remove surface water which follows no definite course even if it deprives an adjoining owner of water which would otherwise come onto his land. Similarly, it is permissible for persons to drain land and allow the water to run into a stream although the consequence is to swell the water in the  stream to a greater extent than before. The  owner had no remedy where a stream overflowed and caused damage, where it could not be shown that injury was due to the unlawful act of the other owner.

The right of drainage does not prevent another adjoining owner from taking the necessary steps to prevent flooding, in order to protect his land.  The right is not absolute.  A person may do no more than necessary, acting with reasonable skill and care necessary to protect his own enjoyment.  He may not act deliberately to injure or damage his neighbour.

If the downstream or adjoining owner prevents the flow, he may, if he acts unreasonably or negligently, be liable in nuisance or negligence to the adjoining owner.

If water which  would otherwise fall from higher ground onto lower-level owners is collected into one body by the owner at higher level by way of a natural use of the property for draining or  otherwise improving it, the owner of the lower-level property generally has no remedy where he  receives that water onto his property.

In recent times the courts have applied principles of negligence to adjoining landowners.  A higher or lower landowner may have duties of care to his neighbours.  In this context, negligence would take account of the reasonableness and cost and expense involved.

Preventing Flooding

Flooding in this context refers to a large and sudden movement of water caused by an abnormal and violent event. A gradual seepage of water is not a flood  this purpose. In contrast to the principles relating to prevention of flooding, refer to  the event of an extraordinary flood.

At common law, the  riparian owner on  a non-tidal river had the  right to raise the riverbanks to confine floodwater within the banks and prevent it from overflowing. This could be done provided it could be accomplished without actual injury to the property of others including those on the other side.  Works which alter the bed of the river and have the effect of increasing its normal flow and  diminishing its flow past other riparian properties, is not covered by the principle.

Where a flood  embankment wss placed some distance from the watercourse the person erecting was not liable where during heavy floods water flowed from the embankment onto his  neighbour’s land. However the action  taken by the riparian owner must be in respect of warding off a common danger, not merely to transfer to another a danger which exists on his own land.

The right to discharge water onto another land by opening sluice gates might be acquired by easement (long use) .

Where riparian owners built wall along the side of the watercourse to prevent flooding and later demolished it in connection building operations with the result that the neighbour’s property was damaged by flood the neighbour was held not to have a right of damages on the ground of negligence nuisance or otherwise.

Just as a higher -level owner can protect himself by banking a river, a lower-level owner can take action to stem excess  flow. There are cases which hold  that the lower-level owner can protect himself by barriers even though this may damage the higher level owner. However, he must act reasonably with care and skill and do no more than necessary to protect his own enjoyment of his property. He must not do so for the purpose of injuring his neighbour.

The lower-level owner can be liable for damages to the upper level owner by reason of nuisance where his action are unreasonable and result in reasonably foreseeable damage to the higher level owner.  In Fitzpatrick v O’Connor in 1988 the defendant raised a bank hundred yards in length and five in height along the boundary with the plaintiff’s land. He was held liable for damages to the plaintiff because it interfered with the plaintiff’s natural drainage and caused corresponding flooding.


Flooding caused by nature and general weather conditions does not usually lead to liability as between owners. The must be negligence nuisance or an accumulation of particular risks. The case between UCC and ESB illustrate the issues involved.

Where a person suffers loss to property or personal injury by reason of the negligence of another, he may usually receive compensation for that damage or loss. An injunction is not generally granted unlike the case with nuisances which protect property rights. Many claims are based simultaneously on  nuisance, negligence as well as breach of legislation such as environmental legislation.

The ordinary principles of negligence are increasingly applied to riparian claims between riparian owners or riparian owners and others. Negligence is a very broad notion by which a person owes a duty of care to others who may suffer loss and damage by reason of his failure to take care.

The duty is said to be owed to a neighbour. A neighbour in this context does not just refer to neighbour in the context of landowning. It refers to any person who may be adversely affected by the carelessness of the person who was sued.

Negligence looks at the approach of the so-called reasonable man (or woman).Where a person acts reasonably and not carelessly, he or she will not usually be liable for the consequences even if they cause loss and damage to another.

Ordinary activities on land which are legitimate and have a good reason will not usually be the subject of negligence, even where damage and loss is caused  to another. If, however activities are undertaken carelessly or the activity has very little good justification and involve throwing an unnecessary risk onto another, then the person concerned is likely to be liable for loss or damage if that arises.

In the UCC v ESB enormous damage was caused to areas of Cork including in particular UCC, when ESB opened flood barriers to prevent a dam burst, causing damage extensively in circumstances of exceptional high rain where they believed they had little choice.

The High Court found liability on the basis of their overall duty and obligation to manage the reservoir and dams concerned. The Court of Appeal overturned this decision and the Supreme Court overturned the Court of Appeal decision. This gives some sense of the elements of subjectivity and assessment involved in common law cases and how the very highest judges can have different opinions on the same facts.

Duty to Take steps?

The common law position is that the riparian owner is under no duty to clear the channel of a watercourse where the river has become silted choked with  weeds and debris due to natural causes. He was not liable to compensate adjoining owners whose land is flooded  in consequence.

The modern law of negligence and nuisance has tended to increase the possibility of liability where a person does something carelessly or deliberately without a good legitimate reason, thereby causing loss and damage to another.

A House of Lords case from 1980 decided that occupiers of land owe a duty in relation to natural hazards on their land that encroach or  threaten to encroach  on to a neighbour’s land. They are bound to act reasonably to prevent and minimise the foreseeable risk to their neighbour’s land.

It has been said that where a landowner knows that his land may flood and spread to the land of his neighbours and the risk is one that can be easily overcome or  lessened by reasonable steps to keep the stream free from blockage, he may not be entitled to stand by under the modern approach to negligence. He may have a duty to warn the neighbour and facilitate remedial action. If the only remedy is substantial and expensive, it  might be that the landowner has discharged his duty to advise neighbours of the risk and/ or  agreeing to permit them to undertake work or share the cost on the basis of a fair sharing of expenses.


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