Preserving fresh water by giving it back to the earth

Hydroblob® is a new type of rainwater buffer. It collects and stores excessive rain and groundwater, as well as normal rainwater (through a connection to your drainage system).

Filtering out and sand or acid, Hydroblob gradually releases all this wager into the surrounding soil, supporting the surrounding environment of plants (irrigation) and groundwater.

How does it work

Most modern drainage systems collect and store rainwater and discharge it into the sewage system. But planned EU legislation will soon require that drainage systems collect rainwater and return it to the soil.

Protecting property and the environment

HYDROBLOB® works in two ways. First of all, it collects and stores rainwater through a connection to your rainwater drainage system. Secondly, HYDROBLOB® absorbs excessive rain and groundwater, protecting the surrounding area and buildings against catastrophic flooding and water damage.

Filtering out any sand or acid, HYDROBLOB® gradually releases all this water into the surrounding soil where it is used in the production of drinking water. By giving fresh rainwater back to the soil, HYDROBLOB® offers a far more efficient way of keeping our water fresh, drinkable and pollution free.

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Local subsidies available

Because of the planned EU legislation regarding rainwater drainage, many local authorities offer subsidies to home owners installing a stormwater buffer. Ask your local municipality for details.

Easy to install

HYDROBLOB® is made up of slender blocks, so you only need to dig a narrow trench to install them. This not only reduces excavation work, it also lowers the cost of carting away the surplus soil. The blocks can be easily connected to form the right size rainwater buffer for your building or garden. It’s a flexible system that’s fast and easy to install.

Long-term durability

Standard plastic buffers may suffer surface damage, requiring repair or replacement. But HYDROBLOB® survives underground in optimum condition for decades. It is, after all, made of rock wool, a natural material produced from molten rock spun into a fibre and bound together in a block. This material resists erosion by plant and tree roots and retains its function for many years. To influence the time in which HYDROBLOB® releases its water volume into the surrounding soil it is wrapped in a membrane filter cloth case which also gives it additional protection and filter function in all directions. The membrane can be used to influence the degree to which HYDROBLOB® releases water into the specific soil.


Getting started

It’s important that your HYDROBLOB® buffer is large enough to absorb and drain all the water that collects on your paving stones or the roof of your building. You can calculate the exact number of HYDROBLOB® rainwater buffer blocks you need using the information below.

How large is the area you need to drain?

When calculating the area of the roof of your house or building, you should only count the side of the roof which has guttering and a downpipe connected to the rainwater buffer. For paved driveways or patios, include the entire paved area.

For a detailed manual for the placement of the products, click here.

What’s your soil type?

Different soil types vary in their ability to absorb and drain water. If you don’t know your soil type, you can perform an infiltration test.

  1. Dig a hole in the ground.
  2. Fill the hole with 30 cm of water and keep the water at that level for 30 minutes.
  3. Next, measure how many centimetres the water level drops in 4 minutes.
  4. If the water level has not dropped significantly after 4 minutes, wait 3 hours (180 minutes) and measure again.
  5. Work out your soil type using the table.




How many HYDROBLOB® blocks do I require?

The number of HYDROBLOB® blocks required depends on the surface and soil type for draining.
The table below can be used to calculate the amount of rainwater buffer blocks you require.

Soil type Infiltration capacity (mm/br) Buffercapacity (liters per 100m2 paved surface) Amount HYDROBLOB® blocks (338 liter units)
sand: more than 30 1500 5
sandy loam: 20 – 30 2000 6
loam: 10 – 20 2500 8
day loam: 5 – 10 3000 9
clay: 1 – 5 3500 11


Ideal for many types of buildings and surfaces, pavings and subsoils 

It is not only your house and basement that need efficient drainage, HYDROBLOB® also protects sun lounges, extensions, carports, office buildings, business premises, sheds, large paved patios and driveways. It can also be used to drain football pitches, tennis courts, golf courses and other sports fields, preventing water saturation that would otherwise disrupt play.


100% rock wool, wrapped in a filter cloth membrane.


30 x 100 x 120: 338 litres of water / 3,72 m2 lateral surface area.
30 x 50 x 120: 169 litres of water / 2,22 m2 lateral surface area.
30 x 30 x 120: 101 litres of water / 1,62 m2 lateral surface area.


HYDROBLOB® contains 94% air. Conventional water buffers contain ca. 30% air only.


30 x 100 x 120: 27 kg
30 x 50 x 120: 13,5 kg
30 x 30 x 120: 8 kg


Integrated; available dimensions Ø 200 mm, Ø 160, Ø 100, Ø 80.


Optionally, an overflow may be fitted to the end of the rainwater buffers. In turn, this pipe may be connected to the sewage or rainwater drainage system; an operation to be performed by a qualified sewage contractor.

Type capacity dimensions contact surface weight
D34 34 l 15 x 20 x 120 cm 0,9 m² 2,7 kg
D112 112 l 30 x 33 x 120 cm 1,7 m² 9 kg
BD112 112 l 30 x 33 x 120 cm 1,7 m² 9 kg
D170 170 l 30 x 50 x 120 cm 2,22 m² 13,5 kg
BD170 170 l 30 x 50 x 120 cm 2,22 m² 13,5 kg
D340 340 l 30 x 100 x 120 cm 3,72 m² 27 kg
BD340 340 l 30 x 100 x 120 cm 3,72 m² 27 kg
Bl169 169 l 60 x 25 x 120 cm 2,34 m² 13 kg





HYDROBLOB® international BV is a Dutch company with extensive experience in water management systems. Our office and our production facilities are located in Schiedam, the Netherlands close to the international seaport of Rotterdam.

Our address: 
Algerastraat 28
3125 BS Schiedam
Postbus 146
3100 AC Schiedam
The Netherlands

Telephone: +31 10 3020000

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