Frequently asked questions

to heating oil tanks

How is a rainwater tank cleaned?

By opening the tank, emptying it and removing the residues from the tank.

Do I need to filter rainwater?

If the rainwater tank is lower than the connections for use (usually the case) by a submersible pump.

The rainwater is filtered as it enters the tank. But be careful! – Rainwater is not drinking water!

How does the rainwater get out of the rainwater tank?

If the rainwater tank is lower than the connections for use (usually the case) by a pump.

Do you need an excavation for an underground rainwater tank in the garden?

For a new tank, yes. For the conversion of an existing tank, no.

How costly is the maintenance of a rainwater tank?

Rain is the washing plant of our air, so small soot particles in particular will get into the tank. Depending on the environment, small leaves may also occasionally get into the tank. However, if the filter is cleaned regularly, this should also not be possible. We recommend pumping out and cleaning the tank every 3 – 5 years. We would be happy to provide you with a quote.

What types of rainwater tanks are there?
How can I convert a heating oil tank into a rainwater tank?
How can a heating oil tank be installed? What options are there for new tank systems?
What is a leak detector? How is a leak detector checked – tested?

Watch the video on the subject of leakage warning devices.

Link: https://wasnerag.ch/service-und-zubehoer/#leckwarnger%C3%A4te

How does tank dismantling work?

Watch the video on the subject of tank dismantling.

Link: https://wasnerag.ch/heizoel/#demontage

What are the benefits of heating oil filtration?

The special filtration with the GAF filter removes even the smallest dirt particles from the heating oil. This ensures that no contaminated heating oil is pumped back into the tank, which could cause breakdowns and damage to the burner.
Oil filtration is usually used when decommissioning tanks. If the oil is heavily contaminated, the head of Equipen will recommend this to the customer.

What are the benefits of a tank coating? How is a tank coating applied?

Watch the video on the subject of tank coating. Link: https://wasnerag.ch/sanierung/#beschichtung

How can a manhole cover be replaced? What are the options for a new manhole cover?
Take a look at the videos on the subject of manhole covers.

Link: https://wasnerag.ch/sanierung/#schachtdeckel

What should you do if the tank room in your property is found to be faulty during a tank inspection?

In concrete terms, this means that the tank compartment, which serves as a catch basin in the event of an accident (overfilling, rusting through of the tank), is cracked or damaged in some other way. According to legal regulations, rooms in which tanks are installed must be leak-proof. This is the only way to prevent leaking, water-polluting liquid from entering the ground and contaminating the groundwater.
Ask us – we will be happy to help you, because cracks do not always mean that the tank room is leaking. By means of a water test, we know definitively whether the compartment is leaking or not.

You can find more information here: https://wasnerag.ch/sanierung/#tankraumsanierung

How are buried tanks refurbished?

By the end of 2014, all single-walled, underground storage tanks had to be fitted with a double-walled safety system. In this installation, a custom-made inner shell is produced on the existing tank. A permanent vacuum is created between the tank wall and the inner shell. The vacuum takes over the task of continuously checking both the tank wall and the inner shell for leaks.

Link: https://wasnerag.ch/heizoel/#sanierung

PDF PDF 190923132311_Merkblatt_E1_September_2019.pdf

When does a tank need to be refurbished?

Defective tank systems are the responsibility of the owner and may only be filled if any defects have been rectified. We specialize in adapting tank systems to the legal requirements.

  • The main causes today are corrosion damage to double-walled underground tanks. Some of the tanks are 50 years old or more.
  • Inner tank shells, usually also for underground tank systems. Some of these inner tank shells are 30 years old or more.
  • Small tanks, also known as plastic tanks, lose their stability with age.
What is an overfill prevention system? What is a filling safety device?

A filling or overfill safety device is a device that automatically stops the filling of the tank when the tank is full.

Filling safety devices are electro-optical probes that are connected to the truck when filling the heating oil tank. The probe emits a pulse when the tank is full. This prevents possible overfilling. A more rudimentary variant for the same purpose is a mechanical overfill protection device. However, this is only recommended where there is no electricity or if it is already installed (in older properties.

Link: https://wasnerag.ch/service-und-zubehoer/#abf%C3%BCllsicherungen

What is a burst safety device?

Watch the video on the subject of burst protection.

What additional costs can be incurred for a tank overhaul?

Possible costs for material replacement and repairs, as agreed between the customer and the tank inspector.

What is included in the price of a tank overhaul?

The price includes the following work and services:

  • Arrival with inspection vehicle and trailer – Set up workplace
  • Temporary heating set up for the duration of the inspection work (heating and boiler work as usual)
  • Pumping out and temporary storage of oil up to 15,000 liters. Removal of the sludge including its environmentally friendly disposal (depending on tank size up to 100 liters)
  • Cleaning and drying out the tank
  • Meticulous inspection of the cleaned tank for any seizures (corrosion) or other leaks
  • Apply or add protective coating to uncoated tanks, then dry (only for steel tanks)
  • Checking the drip tray or protective structure and the tank fittings
  • Leak test of the filling and venting system
  • Closing and filling the tank system
  • Function test and final check
  • Audit report and notification of completion to the competent authority


Seals, material replacement and repairs are not included.

How much oil is left in the tank when it makes the most sense to overhaul it? Does the tank have to be empty for a tank inspection?

Of course, we are happy when the remaining stock is low. We can temporarily store residual quantities of up to 15,000 liters in our largest trailers. This quantity is pumped out at no extra cost to the customer, filtered on request and refilled into the tank.

Do I have to block off parking spaces in front of the property for a tank inspection?

Depending on local space conditions, parking spaces are normally reserved for 2 cars. – Parking spaces near the filler neck are ideal.
If the tank inspection vehicles have to be parked on public land (blue zones or public parking spaces), please inform us urgently. This will enable us to apply for any necessary permits from the city or municipality.

I have received an order. The time has come for a tank overhaul. What exactly do I have to do?

Hand over the responsibility to a specialist company. We will be happy to advise you personally and provide you with a customized tank inspection offer. A tank inspection with internal cleaning minimizes the risk of malfunctions in your heating system and helps to maintain its value. In addition, a tank inspection with internal cleaning fulfills your duty of care and maintains your insurance cover in the event of a claim.
Link: https://wasnerag.ch/heizoel/#revision

What is my personal responsibility or duty of care?

According to Article 3 of the Water Protection Act, everyone is obliged to exercise all due care required by the circumstances in order to avoid adverse effects on bodies of water or groundwater. As the owner of a tank system, you must ensure that your system is regularly checked for defects, in particular leaks, and that any defects are rectified immediately. If you have a tank inspection with internal cleaning carried out by a specialist at least every 10 years, you are also fulfilling your duty of care in terms of the Water Protection Act.

How often should a tank inspection be carried out?

It is generally recommended to have the tank overhauled with internal cleaning every 10 years. The current condition of the tank system always determines whether cleaning is necessary.
Link: https://wasnerag.ch/heizoel/#revision

Do I have to clean my heating oil or diesel oil tank? Is a tank inspection mandatory?

In properties located in groundwater zones S/A/Z, tank inspection is required by law. These property owners will receive a notice. For other installations, an inspection of the storage tank is recommended every 10 years (personal responsibility).

What are the benefits of a tank overhaul?

A tank inspection with internal cleaning increases the operational reliability of your tank system and helps to maintain the value of your heating system.
Link: https://wasnerag.ch/heizoel/#revision

Where can I obtain information about my heating oil tank?

Contact the responsible cantonal office. See list of cantonal offices for environmental protection in Switzerland We can of course also carry out any clarifications on your behalf (except for the canton of BE).

I Filled My Tank in Spring. Up to how many liters can you take from my tank at no extra cost?

Up to a maximum of 15,000 liters. However, it is important for us that you can give us as accurate information as possible about the heating oil level. This enables us to arrange the right tank trailer for you for temporary storage. The easiest way to do this is to measure the oil level with the dipstick. (Instructions / in progress).

We have placed the order with you, when will you inform us about the date of the revision?

As the customer, you determine the timing as a priority. The ideal time for us is
– to carry out the revision before refilling.
– if you as the customer are at home. If this is not possible, we will find a solution.
– if you give us a time period – so we can schedule as optimally as possible.
In principle, we always schedule at least one week before the date if possible. Ideally by telephone or e-mail.

I would like to replace my underground tank with a small tank system. How should I proceed?

We recommend that you check both the renovation of your underground tank and the new small tank system. The price differences are often not as great as often assumed. We will be happy to offer you both options.

I would like to install an oil heating system. Can I also place the small tanks in the garage or in the shelter?

Heating oil should be stored in a dark place with as little temperature fluctuation as possible. Second-hand tanks should not be older than 10 years. It is worth having the installation carried out by a specialist company.

I want to take my heating oil tank out of service. What options are open to me?

Decommissioning, decommissioning including dismantling or, in the case of underground tanks, conversion to rainwater tanks.

Do I also have to have my small tank (household tank/plastic tank) decommissioned by a specialist company?

Yes, an officially approved tank must be decommissioned by a specialist company, regardless of its size. Specialist companies are companies that employ trained specialist personnel with the necessary equipment and experience. Here you will find the legal basis. https://www.wasnerag.ch/de-ch/Heizoel/Tankrevision/Gesetzliche-Grundlage

Is a tank overhaul also possible in winter? How long does the heating fail during a tank overhaul?

On request, we can also carry out a tank overhaul without interrupting the heating system. For this purpose, we create a temporary heating system for you at no extra cost (a provisional oil feed for your heating system)

10 years have passed since the last tank overhaul. Why don’t I receive a new request from the Water Protection Office?

Since January 1, 2007, owners of tank installations in water protection zone B no longer receive a request for tank inspection from the respective water protection office. However, the invitation is officially published (gazette). The responsibility for the regular maintenance of the tank system and liability in the event of damage therefore lies entirely with the owner of the system.
We recommend that you have the tank inspection with internal cleaning carried out every 10 years, as before, in order to maintain operational safety and preserve the value of the tank, even without state compulsion. With longer intervals, the prescribed regularity is no longer guaranteed. This may result in a reduction in insurance cover.

Why is a tank overhaul with internal cleaning recommended?

Heating oil is an organic product and is therefore subject to a natural ageing process. Temperature fluctuations during the year cause condensation to form which combines with oil sediments. Even today, certain heating oils already contain bio-oil. All of this then collects on the bottom of the tank. This sometimes quite aggressive oil sludge can lead to corrosion in the tank. With larger quantities – which is rather rare – there is also the possibility that it can enter the heating burner via the product line.
With an internal tank cleaning, we guarantee you 10 years against rusting through of the tank, which also removes oil sludge and condensation. The result: your heating system will work more reliably for years to come.

to diesel oil tanks

I would like to install a diesel tank. Can I also place the small tanks in a garage or shelter?

Yes – but the most important thing is that you are aware in advance that the “small filling station” is accessible in such a way that the vehicle to be refueled can be refueled in a tight space. There are clear regulations for this.

https://wasnerag.ch/wp-content/uploads/2025/10/2011_Dieseloelbetankunsanlage_Schemenblatt_D1.pdf

Diesel oil should also be stored in a dark place with the lowest possible temperature fluctuations. The installation of such a system requires a permit. As a specialist company, we are happy to support you.

Why is a tank overhaul with internal cleaning recommended?

Diesel oil is an organic product and is therefore subject to a natural ageing process. Temperature fluctuations during the year cause condensation to form which combines with oil sediments. Even today, diesel oil is normally mixed with a proportion of bio-oil. All of this then collects on the bottom of the tank. This sometimes quite aggressive oil sludge can lead to corrosion in the tank. Larger amounts of sludge and water can lead to combustion problems in the engine.
With an internal tank cleaning, we guarantee you 10 years against rusting through of the tank, which also removes oil sludge and condensation. Conclusion – with clean storage, annoying and usually expensive damage to vehicles can be avoided.

10 years have passed since the last tank inspection. Why have I not received a new request from the Water Protection Office?

Since January 1, 2007, owners of tank installations in water protection zone B no longer receive a request for tank inspection from the respective water protection office. However, the request is officially published (gazette). The responsibility for regular maintenance of the tank system and liability in the event of damage therefore lies entirely with the owner of the system.
We recommend that you have the tank inspection with internal cleaning carried out every 10 years, as before, to maintain operational safety and preserve its value. If the intervals are longer, the prescribed regularity is no longer guaranteed. This may result in a reduction in insurance cover.

to gasoline tank systems

By when did the flame arrester have to be installed?

Until 2017, see SUVA leaflet 1 and leaflet 2.

Are tank inspections at filling stations also possible at night?

For heavily frequented filling stations with difficult space conditions, we offer you the option of carrying out inspections at night.

to rainwater tanks

Should I install my new rainwater tank in the cellar or in the garden?

Installation in the building always involves a certain risk. This problem can also occur with an underground rainwater tank. However, its effects are much less unpleasant underground than in the basement.

What size of rainwater tank is recommended?

Primarily you have to know what the need is

  • Garden irrigation
  • WC flush
  • Washing machine

Tanks of 5,000 liters or more make sense – or larger, depending on requirements.

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