groundwater

You want to build underground, for example to create a cellar or basement. Then you, as the owner of a building, house or garden, are responsible for taking measures against groundwater flooding. This also applies to existing buildings. Underground spaces such as cellars and basements where people regularly stay must always be waterproof.

What's going on

  • Groundwater is the water in the ground that you often do not see, but is very important for nature and our drinking water
  • Groundwater can rise due to rain that sinks into the ground. During drought, groundwater can also drop again
  • Groundwater levels have risen everywhere in the Gooi in recent months. This is because it rained a lot and for a long time from mid-October 2023 to February 2024. This rainwater sinks into the ground everywhere. This causes the groundwater level to rise
  • The groundwater level responds to rain with a delay. As a result, it takes longer before the groundwater level drops again. In an average year there are higher groundwater levels in the months of February and March and the groundwater drops again in the month of April
  • The groundwater system in the Gooi and the Heuvelrug behind it is also large. Rainwater that seeps into the soil in the Heuvelrug behind it (east of Hilversum) flows via the soil to the polder west of Hilversum. In a normal year, this causes higher groundwater levels in February and March. This will also happen this year (2024). But now this is on top of the already high groundwater level as a result of the heavy rain at the end of 2023. This is an exceptional situation. As a result, it will also take longer for the groundwater level to drop again.
  • In 2023, groundwater levels already rose to exceptionally high values ​​in November. This was due to the extreme rainfall that lasted for months. The groundwater level in the Gooise groundwater system drops slowly, which is why it is still relatively high in 2025. The spring of 2025 is very dry, which means that the groundwater level will drop faster than in a year with average precipitation.
  • Mostly in Hilversum East there was nuisance in 2023/2024 due to the high groundwater level. There is no surface water here, such as rivers, lakes or canals. In the west of Hilversum, the water can go to the Gooise Vaart and the Hilversums Kanaal. But from two-thirds of Hilversum, the water flows to the east. There is only a buffer at Anna's Hoeve, but that is also very full. In addition, Hilversum-Oost is relatively low compared to, for example, the Trompenberg in the west and the higher parts towards Lage Vuursche

What the municipality can do

  • The municipality has almost no influence on the groundwater level. The groundwater system is enormous and difficult to manage
  • The municipality's sewer system is intended for rainwater (rainwater) and has no function for draining groundwater
  • We are now looking for solutions to reduce the groundwater nuisance that certain neighborhoods have experienced. In this way, we are trying to free up extra space in the sewer system, the few waterways, ponds and lakes. For this, we are in contact with other parties such as Rijkswaterstaat, the province of North Holland, the Water Board Amstel, Gooi and Vecht, Natuurmonumenten and the Goois Natuurreservaat. If more is known about this, you can read it on this page

The groundwater level explained

  • The groundwater level or groundwater level indicates how deep the groundwater is
  • The groundwater level in Hilversum fluctuates a lot. The difference between summer and winter can be more than 1 meter. Normally this does not cause any problems
  • In a polder with many ditches, the water board can regulate the water level. That is not possible in Hilversum. On the higher sandy soils here there are no ditches and the groundwater follows natural rises and falls
  • In the future, groundwater levels may rise more and extremes may occur more often, for example due to climate changes

Groundwater measurements

  • We often measure the groundwater level in NAP (Normal Amsterdam Level). It is important to see what the height of the ground is compared to the NAP. This way you can clearly see how deep the groundwater is compared to your house or basement
  • Due to climate change, extreme weather events are increasing, which reduces the “manufacturability of the living environment” with the help of artificial measures

Current groundwater level 

April 2025: The groundwater level is the same as in recent 'normal' years

In 2024 new wells were added. Some wells in Hilversum-East are equipped with an online groundwater registration.

On the map you can see the groundwater measurements of Hilversum see:

  • Click on the card on a measuring point (a purple circle), the graph appears at the bottom of the screen (may take a while)
  • By clicking on 'Ground level' in the graph legend, the groundwater measurements are zoomed in (the ground level height then disappears from the graph)
  • A different time period can be selected at the top right

Hilversum East

The high groundwater level has caused inconvenience and damage in various places in Hilversum. Information meetings were held in the autumn of 2024 for residents who suffered damage, see more about this on Hilversum East.

What you can do yourself

  • If you want to build underground, take the groundwater and the expected rise of groundwater in the future into account
  • Underground spaces such as cellars and basements where people regularly stay must always be waterproof. This is a condition from it Buildings and Living Environment Decree (Bbl, articles 3.64 and 4.118). As the owner, you are responsible for this yourself.
  • As the owner, you are responsible for taking structural and/or water management measures to make your basement waterproof
  • As the owner of a building, house or garden, you are also responsible for taking measures against groundwater flooding on your own property.
  • Place vulnerable objects (such as electricity or photos) safely in a high place
  • Expert companies or contractors can help you waterproof your basement or take measures against groundwater flooding. In the short term, for example, they can help you get your basement dry. If you want to keep your basement permanently dry, the solution is to waterproof the basement down to ground level. Also consider measures against moisture creeping up on exterior walls and floors
  • No moisture problems in your basement yet? Then it is wise to have your cellar checked
  • It is becoming increasingly important to accept the influence of extreme weather conditions. Landowners must prepare for the future, where groundwater levels may rise and during intensive rain showers (a lot of rain in a short time) water may temporarily stand at ground level  

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