Sewage, wastewater and rainwater

If you are building a new house or holiday home, you must apply for a permit from the municipality (drainage of wastewater from the household and roof and surface water), eg connection to sewer, discharge to lake, sea or watercourse or seepage of roof and surface water.

You can always get advice and guidance from an authorized sewer master or contact us. 

Remember that only authorized persons may carry out work with wastewater drains.

Do I have to do sewer separation on my property?

In urban areas, properties with one culvert to the sewer system will eventually separate wastewater and roof and surface water (sewer separation), while the properties in the open country that will be sewered must connect the wastewater to public sewers, cf. The wastewater plan. The roof and surface water must be handled privately on the plot.

The wastewater is led to a treatment plant, while the rainwater is led to the nearest lake, stream or sea.

If you need to separate the wastewater on your property, you have the option of getting a sewer plan of existing conditions if the municipality has it in its archives. You can access the digital archive yourself by contacting Sønderborg Municipality's Department, Building & Housing: byg-bolig@sonderborg.dk

I have received a letter about a faulty connection or leakage - what does it mean?

If you have received a letter from Sønderborg Municipality about a faulty connection or leakage, it is because an investigation of the public sewer system has been carried out, which shows how the system receives rain and wastewater from your property. The investigation was carried out by SONFOR and is intended to identify whether there are conditions on the property that may burden the public sewer system.

The studies can show whether there is:

• Faulty couplings,
  where rainwater from, for example, the roof or driveway is connected to the sewage pipe instead of the rainwater pipe or vice versa.
• Leakage,
  where rainwater or groundwater unintentionally flows into the wastewater system, but it can be the other way around.

These conditions most often occur in areas with separate sewers, where rainwater and wastewater must be kept separate.

Faulty connections and leaks are not permitted and must therefore be repaired. The purpose is to ensure that the sewer system functions correctly and to avoid unnecessary strain on wastewater systems and the aquatic environment.

We recommend that you contact a licensed sewer engineer who can help investigate the conditions on your property and possibly rectify the fault. You are also welcome to contact the municipality if you have any questions about the matter.

Please note that work on sewer installations may only be carried out by authorized sewer technicians.

If you want a more detailed explanation of what misconnection and overleakage are, you can read the technical description here.

What should I be aware of if I need to establish my own cleaning solution?

If you need to apply for the establishment of your own treatment plant for improved purification of your wastewater, we have made some short checklists of the information you need when you apply via the self-service solution on this page.

If you have previously had your wastewater in a settling tank, this should now be cleaned better, then water quality in watercourses is improved. In that case, you will receive an order to this effect with more information.

Can I establish a fascine or make a LAR solution for rainwater on my land?

Establishment of a fascine, other form of local drainage of rainwater or discharge of surface water requires the permission of the municipality. You can apply via the link at the top of the page.

As a landowner, you must carry out the work yourself with fascines and associated wires. However, you must never make the connection and disconnection to the existing sewer system yourself - this work is reserved for an authorized sewer master. The landowner is also responsible for the maintenance of the fascine.

Distance requirements

Fascinators for drainage of rainwater from roof areas are placed on the property's own plot with at least 2 m from boundaries and 25 m from drinking water wells, drinking water wells, streams, lakes and the sea. The distance to inhabited buildings must be at least 5 m. In the case of buildings without dwellings and without basements, the distance requirement can be reduced to 2 m.

If you have a property with a basement where there are problems with moisture on the basement walls, seepage of rainwater near the house can aggravate damage - even if the distance requirements are met. You can therefore consider placing the fascine further away from the house than the distance requirements prescribe.

Soil conditions

In some places the soil is unsuitable for seepage. 

Sand and gravel are very suitable for infiltration. Moraine soil with clay requires larger fascines, while very dense clay soil can be problematic to establish fascines in. If the fascine is placed in dense soil/clayey soil, the fascine should be placed in a place where it does not matter if it becomes swampy during wet periods, for example in the perennial bed.

Collection of rainwater for toilet flushing and laundry

If you want to use rainwater for toilet flushing and laundry, then you can set up the system under the following conditions:

• You must apply for a permit to collect rainwater for toilet flushing and laundry at Byg & Bolig (for private individuals) by phone +45 88 72 40 82  or Business & Waste (for companies) by phone +45 88 72 40 83.
• You must inform the municipality's construction department to update the BBR register
• Installations for collecting rainwater from roofs for use in toilet flushing and machine washing must be carried out in accordance with the applicable Pipe center instructions prepared by the Ministry of Economic and Business Affairs and the Ministry of the Environment
• All work must be carried out by authorized sewer masters and plumbers

A water meter must be installed on the system, and you must pay a water diversion fee for the rainwater used. Please contact Sønderborg Forsyning (SONFOR) via info@sonfor.dk to learn more about water diversion fees.

The use of rainwater for toilet flushing in institutions and buildings with public access may only take place with the permission of the City Council after discussion with the National Board of Health. The City Council cannot grant permission for the use of rainwater for toilet flushing and laundry in institutions for children under 6 years (eg daycares and kindergartens), hospitals, nursing homes and other institutions for particularly sensitive groups (eg physically and mentally handicapped).

Can I postpone the deadline for connecting to the sewer or get an installment plan?

If you are a homeowner, you can apply for the following:

• A deadline of at least three years to fulfill the municipality's order to improve wastewater treatment or sewerage.
• Only to have to pay the connection fee when the connection of the property to the sewer is completely finished.
• Right to an installment plan over 20 years at Sønderborg Forsyning, for expenses to fulfill the order and any connection contribution.
• That your children's income is not included in the total household income, and that your children's wealth is not included in the calculation of the wealth supplement.

To be eligible for financial assistance, the following conditions must be met:

• The household income for the property owner's household must be less than DKK 363.222 plus any supplement per. child of DKK 47.582 (up to 4 children under 18 living at home).
• Wealth (including, among other things, the value of real estate, etc.) over DKK 1.060.300 must be recognized in household income.
• The amount limits are indicative and are regulated every year.
• Orders for separate sewerage are not covered.

The household includes the property owner and anyone who has an address on the property and is not a tenant. Children who have an address on the property count.

If you are approved for an installment plan, you must contact Sønderborg Forsyning, who will help you further with this. Read more about payment for wastewater management here.

Can I take out a loan as a pensioner or post-retiree?

If you are over 65, a pensioner or a post-retirement recipient, the municipality offers you a loan to pay the connection fee and costs for improving the sewer on your own property. The loan is also called the freezing of property tax.

It is a requirement that there is free value in the property and that the property is used for living. Read more about the scheme.

Can I discharge wastewater into my own sewer when, for example, washing my car?

If your home is sewer separated, wastewater is led from the toilet and sink to the treatment plant, while water from roads, roofs and tiles is led to the nearest stream or lake.

Therefore, avoid pouring water with soap or chemicals into your garden, driveway or weather grid, where it ends up in nature and harms plants and animals.