New Rainwater Management Regulations for Developers in the Czech Republic

Rules for rainwater management in the Czech Republic have become significantly stricter. Developers are now required to primarily retain rainwater on-site, which is not merely a recommendation but a legal obligation under the threat of substantial fines. Many property owners underestimate this duty, leading to administrative complications during the permitting process or final building inspections. Discover the precise requirements of Czech legislation and why it pays to cooperate with our Prague-based legal experts in this field.

Quick Summary

• Legal obligation: Both the Czech Water Act and the implementing decrees to the new Building Act impose an obligation to capture and regulate rainwater directly on the property. This applies to new constructions as well as modifications to existing buildings.
• Hierarchy of solutions: Czech legislation clearly defines a preference – first infiltration, if not possible, then retention and regulated discharge into a separate rainwater sewer, and only as a last resort, regulated discharge into a combined sewer system.
• Sanctions and inspections: Illegal discharge of rainwater into the public sewer system without a permit carries a risk of a fine of up to CZK 100,000 for individuals.
• Complexity in practice: The correct solution requires a hydrogeological assessment and compliance with Czech Technical Standards (ČSN). Our attorneys in Prague at ARROWS handle these issues daily and will help ensure the legal security of your project.

Legal basis and the obligation to retain water in the landscape

Rainwater management in the Czech Republic has undergone a fundamental change. For many years, the principle was to discharge water into the sewer system as quickly as possible. However, this approach led to the disruption of the natural water cycle and problems with overloading wastewater treatment plants.

The key legal framework is Act No. 254/2001 Coll., on Waters (the Water Act), which establishes the obligation to ensure the infiltration or retention of precipitation water. This requirement is further elaborated in regulations related to the new Czech Building Act and in the decree on construction requirements.

The Czech state administration recognizes that effective rainwater disposal directly on-site is one of the most effective tools for climate change adaptation. Therefore, this obligation is being enforced with increasing strictness.

The obligation applies not only to new buildings but also to changes to existing structures, such as extensions or construction modifications that change runoff conditions. If you are applying for a project permit in the Czech Republic, you must simultaneously resolve precipitation water management.

MicroFAQ: Basic concepts and definitions

1. What is meant by the term "precipitation water"?
Precipitation water is water resulting from atmospheric precipitation hitting buildings and land. This is water that must not be mixed with sewage water without a permit. Our Prague-based attorneys often handle cases where owners disregard this definition and illegally connect rainwater pipes to the sewage system.

2. Does this obligation apply to all buildings?
The obligation applies to the vast majority of buildings, whether they are family houses, apartment buildings, or commercial premises. Exceptions are minimal and relate to very specific situations under Czech law.

3. What happens if I do not fulfill this obligation?
You face a fine under the Water Act or the Act on Water Supply and Sewerage, and most importantly, the refusal of a project permit or occupancy permit (final inspection approval).

Hierarchy of solutions under Czech law

The law does not allow for an arbitrary choice of solution. Instead, it defines a binding hierarchy of procedures that developers must respect. You cannot choose an administratively simpler option if a priority option is technically feasible.

Preference of procedures from infiltration to discharge

According to Section 5(3) of the Czech Water Act and the decree on construction requirements, the order is as follows:

1. Infiltration of rainwater on the property

The first and preferred solution is to let rainwater soak directly into the ground on the developer's property. This solution is most desirable as it supports the natural water cycle and is implemented using infiltration facilities.

For infiltration to be considered fulfilled, the land must be geologically suitable and sufficiently large. The new Czech decree on construction requirements no longer works with fixed percentages but refers to standard values and spatial planning documentation.

2. Retention and discharge into a separate rainwater sewer

If infiltration on your property is demonstrably not possible, the second option comes into play: retention and regulated discharge into a watercourse. This usually happens via a rainwater sewer that does not lead to a treatment plant.

3. Regulated discharge into a combined sewer system

Only in cases where infiltration is not possible and a separate rainwater sewer does not exist in the locality does Czech law allow for regulated discharge of rainwater into a combined sewer system. The emphasis is on the word "regulated," which means the necessity to retain the water on the property and discharge it gradually.

MicroFAQ: Practical questions on the hierarchy

1. What happens if I drain water into a combined sewer without a permit?
You are committing an administrative offense. You face a fine and the obligation to pay sewage charges retroactively. The sewer operator can detect illegal connections using, for example, a smoke test.

2. Can I choose direct discharge into the sewer because it is cheaper?
No, you must follow the legal hierarchy. If a hydrogeological assessment proves that infiltration is possible, the Czech authorities will not permit a direct connection to the sewer.

3. Who proves the impossibility of infiltration?
The burden of proof is on the developer. You must submit a hydrogeological report that clearly states why infiltration is not possible.

Hydrogeological survey as an essential foundation

A common mistake that our Czech legal team at ARROWS encounters is the absence or low quality of a hydrogeological survey. Without it, it is impossible to legally design a method for precipitation water disposal.

What is a hydrogeological survey and why is it important?

A hydrogeological survey is conducted by a person with professional competence. The goal is to determine the infiltration capacity of the soil and the groundwater level. The survey serves as a crucial legal and technical basis for project documentation in the Czech Republic.

The survey usually includes:

• probing work on the property,
• on-site infiltration tests,
• risk assessment (impact on neighboring properties, wells, subsoil stability).

The price for a quality hydrogeological survey for a family house is in the range of lower tens of thousands of Czech crowns. It is an investment that prevents serious errors in the project.

How this foundation is used in practice

A hydrogeological assessment is attached to the application for a project permit. Based on this, the official at the building authority assesses whether the proposed solution corresponds to the reality on the land. If the assessment is missing or incorrect, the authority will suspend the proceedings or reject the application in accordance with Czech law.

Our attorneys in Prague recommend securing an assessment as early as the study phase so that the designer knows what size retention tank or infiltration facility to account for.

Mgr. Karel Huneš

associate

• hunes@arws.cz

JUDr. Tereza Snopková, Ph.D.

associate

• snopkova@arws.cz

Rainwater Management Systems and Equipment

The choice of technical solution must comply with the Czech standard ČSN 75 9010 (Infiltration facilities for precipitation water).

Types of Equipment

• Surface infiltration facilities: Swales, trenches, infiltration basins. These are more space-intensive but easier to maintain and aesthetically pleasing.
• Underground infiltration facilities: Infiltration blocks and tunnels. These save surface space but require thorough filtration before entry to prevent clogging.
• Retention tanks with water utilization: Underground tanks where water is accumulated for further use.

Dimensioning is Key

The size of the infiltration facility is calculated based on:

• the size of the drained area (roof, paved surfaces),
• the infiltration coefficient (from the hydrogeological assessment),
• design precipitation totals (according to the periodicity and duration of rain).

Under-dimensioning an infiltration facility is a frequent cause of disputes in the Czech Republic. If the facility overflows during heavy rain and floods a neighbor's property, the property owner bears liability.

MicroFAQ: Practical Questions Regarding Equipment

1. Which solutions require a permit?
An infiltration facility is considered a water structure under Czech legislation if there is direct discharge into groundwater. However, if you are building a separate large retention system or discharging into a watercourse, a water management permit is required.

2. What is the maintenance?
The equipment must be inspected and cleaned (filters, sediment traps) at least twice a year and after torrential rains to prevent blockage.

Legal Risks and Sanctions

Underestimating rainwater management issues carries public law risks in the form of state fines, as well as private law risks, which include disputes with neighbors.

Fines for Illegal Discharge into the Sewerage System

If you drain rainwater into a combined sewerage system without a permit and a concluded contract, it constitutes unauthorized discharge under Czech law.

• Fine amount: According to the Czech Act on Water Supply and Sewerage Systems, the fine for an individual can reach up to CZK 100,000. For legal entities and entrepreneurs, sanctions range from hundreds of thousands to millions of Czech crowns.
• Detection: Municipalities and sewerage operators use "smoke tests." Harmless smoke is blown into the sewer, and if it emerges from your gutters, an illegal connection is proven.

Rejection of Final Inspection (Kolaudace) or Permits

The Czech building authority may not issue a final inspection certificate or consent for use if the implementation of rainwater management does not correspond to the approved project. This can block the use of the property or the drawing of a mortgage loan.

Neighbor Disputes and Damages

Under the Czech Civil Code, you must not annoy a neighbor beyond a reasonable degree by draining water onto their land. If your poorly designed infiltration causes dampness in a neighbor's house or erosion of their garden, you are liable for the resulting damage, and the neighbor may seek a remedy through Czech courts.

Our Prague-based attorneys represent clients in cases where incorrect drainage has caused extensive property damage.

Easements and Neighbor Rights

Rainwater issues significantly affect neighbor rights regulated by the Czech Civil Code.

Eaves Easement

A landowner may have an obligation to tolerate water from a neighboring roof flowing onto their land if an easement (věcné břemeno) has been established for this purpose. Without a valid legal title, such as a contract or prescription, you do not have the right to discharge water onto a neighbor's land.

Right to Rainwater Drainage

The owner of land onto which water flows naturally from a neighboring higher-lying plot must accept it. However, there must be no intentional diversion of water without an agreement or easement. If a neighbor modifies the terrain so that water now flows toward you and causes damage, you have the right to defend yourself and demand adjustments under Czech law.

Subsidy Support: New Green Savings

The Czech state motivates the use of rainwater through the New Green Savings (Nová zelená úsporám) subsidy program.

What Can Be Financed

A contribution can be obtained for the acquisition of a rainwater retention tank, where the subsidy can cover up to 50% of eligible expenses. The amount of support depends on the method of water use—whether it serves only for garden irrigation or also for flushing in the house.

Conditions

The applicant can be the owner of a family house or apartment building in the Czech Republic, and the program supports both new constructions and renovations. For new buildings, support is usually conditional on the water being used within the house as well, not just for irrigation.

Although the administrative process has been simplified in some calls, a professional technical calculation is still essential for the correct design of the system and trouble-free operation. You will always need it for Czech building proceedings.

Conclusion

Rainwater management is currently an unavoidable legal obligation in the Czech Republic. Ignoring the law can lead to high fines, problems with final inspections, and expensive neighbor disputes. The correct procedure involves verifying infiltration possibilities, designing a technical solution, obtaining permits, and subsequent maintenance.

Our Czech legal team at ARROWS law firm handles this agenda comprehensively, from preparing easement agreements to representation in damage compensation disputes. Our experience helps clients avoid complications when defending themselves in administrative proceedings.

If you want to realize your project safely, contact our law firm in Prague at office@arws.cz. We will help you navigate the legislation and prevent future problems.

FAQ – Most Frequent Legal Inquiries

1. Is a hydrogeological assessment mandatory?
For the purposes of building proceedings for a new building or extension in the Czech Republic where infiltration is being addressed, the assessment is generally a necessary document for verifying infiltration conditions. Without it, a designer cannot responsibly design an infiltration facility.

2. What happens if I build a house without a proper rainwater solution?
You risk the non-issuance of a final inspection certificate, a sanction for a water management offense, and liability for damages caused to neighbors.

3. Will the building authority require infiltration even if it is not technically possible?
No, if a hydrogeological assessment proves that infiltration is not possible, the authority must accept the next solution in the order prescribed by Czech law. However, the authority cannot accept a mere assertion without evidence.

4. What are my rights if water from a neighbor's property flows onto my land and causes damage?
Under the Czech Civil Code, you have the right to defend your property and demand that the neighbor takes measures to prevent water from flowing onto your land, particularly if the water originates from their building or artificially modified terrain.

Disclaimer: The information contained in this article is for general informative purposes only and serves as a basic guide to the issue. Although we strive for maximum accuracy, Czech legislation and its interpretation evolve over time. To verify the current wording of regulations and their application to your specific situation, it is essential to contact ARROWS law firm in Prague directly (office@arws.cz). We bear no responsibility for any damages or complications arising from the independent use of information from this article without our prior individual legal consultation and professional assessment. Every case requires a tailored solution under Czech law, so please do not hesitate to contact us.

Read also:

• Cross-Border Construction Law and Building Due Diligence in the Czech Republic: What Foreign Investors Should Know
• Who Can Be a Party to Czech Building Permit Proceedings?
• Czech Environmental Inspectorate: what to watch out for in manufacturing companies
• Operating Without a Licence in the Czech Republic: Legal Consequences Explained