What are the rules for having a septic tank in Spain?

A septic tank or fosa séptica in Spanish is typically an underground container which is used for wastewater treatment in areas that don’t have access to a municipal sewage system. They cover the treatment of wastewater from bathrooms, kitchen drains and laundry for example.

The EU directive 91/271/CEE establishes all the guidelines that European Union Member States must follow to ensure that urban wastewater is treated properly before being discharged into the environment, as well as minimum environmental objectives that they must meet.

There are also country wide laws that regulate the management of sewage, wastewater and the quality of water for human consumption, but mainly the rules for installing a septic tank in your property vary from region to region and are managed separately.

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These set out the legislation for technical regulations, capacity and dimensions, construction materials, drainage systems, as well as maintenance and emptying.

Generally there are several rules which are similar across the board. These include:

• There should be no municipal sewage system in the immediate vicinity.
• The septic tank pit must be between 5 and 8 metres from the house and other homes or buildings. It must also be at least 30 metres away from risk areas such as wells, ponds, streams, etc.
• The distance from irrigated areas for crops, orchards, etc. and water sources like rivers and lakes should be at least 50 metres.

It’s important to note that some municipalities do not allow the installation of septic tanks, but they do allow the installation of sealed tanks. Septic tanks contain a filter, while sealed tanks do not, therefore waste must be removed by specialised technicians.

Other areas like Dénia on the Costa Blanca for example, is forcing all residents to be on the sewage system and are deactivating private septic tanks and issuing fines.

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To install a septic tank in Spain, several permits and authorisations must be obtained to ensure compliance with current regulations. These include:

A building permit or licencia de obras – This is a type of planning permission which you must apply for at your local city council. In order for it to be granted, you will need a technical project, created by a professional.

Environmental Authorisation - Certifies that the installation will not have a significant negative impact on the environment.

Health Report - This ensures that the septic tank will not affect public health and is issued by the local health department.

Discharge Permit – This authorises the discharge of treated wastewater. It can be applied for at the Hydrographic Confederation.

Activity License – This may be required in certain cases, especially for larger installations.

Installation Certificate – This verifies that the installation has been carried out correctly and can only be issued by a qualified technician.

While it’s most likely you will need all of the above, it’s important to consult with your city council and the competent authorities in your region to make sure that you meet all the requirements there.

In any case, it’s not possible to install a septic tank without the proper permits and permission.

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One of the main points to take into consideration is tank drainage system to make sure you prevent contamination. Ways to do this include:

• An infiltration field of perforated pipes in gravel-filled trenches.
• Infiltration beds filled with gravel
• Ensuring that it’s built away from drinking water sources and homes.
• Making sure it’s located in soil suitable for infiltration.
• Build it land with a slope to facilitate flow.
• A ventilation system is key to prevent gas buildup.

Fines for non-compliance with rules

You must ensure you meet current regulations and that process is carried out safely and without harming the environment. Installing a septic tank without the necessary permits can result in legal penalties and fines. You will also be forced to remove your tank.

In worst-case scenario the cost of the fine can reach up to €1 million, but for an illegal septic tank it would amount to €7,000, not including any damages caused by the waste.