Closed tanks

CPX closed tanks for waste water, drinking water or irrigation are available in different sizes from 1250 to 6000 litres. The tanks are suitable for both below-ground and above-ground installation. Our green, child-proof hatch blends into its surroundings and comes with all tanks as standard. 
CPX closed tanks can be used as drainage tanks for WC (Black water) at normal or high levels of protection. A closed tank collects all waste water and no water is filtered and discharged into the ground. 
All our tanks – and our green hatches – are approved by SP (RISE), thus indicating they fulfil the relevant European requirements. All CPX closed tanks can, if desired, be equipped with connections, level alarms and various riser necks. Owing to their being constructed of FC approved (Food Contact) materials and certified by Normpack, CPX closed tanks can also be used for rain or drinking water storage.

  • Low profile design
  • Recyclable
  • Robust and durable  

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Low profile design 

Our large closed tanks, of 3000, 4000, 5000 and 6000 litres respectively, enjoy a very low profile. This means that transport is optimised and the tank need not be dug down so deeply, saving both time and money. Having a low-profile tank can really make a big difference, especially when there is a risk of running into compact rock during excavation. 


All CPX closed tanks are made of rotationally moulded, ageing-resistant PE (Polyethylene) which is 100% recyclable and allows circular use. Nothing leaches from the material, moreover, or leaves the tank during its lifetime, so in addition to the positive aspects of collecting wastewater, the ground where the tank is placed is not affected. 

Robust and durable 

Both the structure and material have been developed without compromising on function and quality and are designed for Scandinavian conditions. The septic tanks are self-supporting, which means that they can even be used above ground, without being dug down. This is only possible with tanks that are stable. The installation depth of up to 2m is also testament to just how robust the tanks are and that they will function safely for a very long time.  

Choice of closed tank

Every property's requirements are different and we have taken this into account by developing a range of flexible options. 
When choosing a tank, you have to take the conditions that are unique to each property into account. It pays to make a thorough assessment of the situation and seek advice before making the appropriate choice. The size of the tank depends on how much it is to be used and how often it will need to be emptied. It is often a good idea to choose a larger tank as this can make things easier and save money in the long run.  

Type of waste water  

Waste water from a property is divided into 2 types, black water and grey water, and the type of waste water influences the choice of tank. The difference between the two is that black water includes toilet waste water, while grey water is water from bath, shower and laundry only. Note that regulations differ between municipalities so make sure you know which rules apply in the municipality concerned.

Protection level 

Every property/location is classified on the basis of a level of protection in which proximity to surface water such as a lake/sea or groundwater plays a role. Sweden operates with 2 levels of protection: a general normal level of protection and a high level of protection. We recommend getting advice to ensure that the correct classification is made before choosing a drainage system.  

Placement of closed tanks

The tank needs to be placed so there is a fall from the property to the tank. Ease of access for vacuum trucks for emptying purposes should also be considered.

Operation and maintenance of closed tanks

A tank needs to be emptied regularly by a vacuum truck, at which times it should also be inspected. A level alarm, available as an accessory, can indicate when a tank needs to be emptied.

Closed tank safety    

Our closed tanks come with a child-proof hatch that cannot be opened without tools. The hatch is designed to stop people stepping through it, but not to bear the weight of a car or other heavier vehicle. Never descend into a waste water tank while it is in operation!   


CPX Irrigation kit for rainwater

Using our irrigation kit in combination with a closed tank makes it possible to store and reuse rainwater. This is a sustainable solution that avoids using purified drinking water for irrigation and also allows watering during so-called hosepipe bans. 
The rainwater kit consists of a submersible pump, a filter at the inlet and a green lid with two integrated Gardena connections. The rainwater kit can be retrofitted to an existing tank.
The irrigation kit can be found under accessories, buriable tanks. 

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Bror Sjölund
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Carolina Brand
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