Water from every direction

Asphalt, concrete and garden tiles prevent rainwater from entering the ground. Therefore, it is often a good idea to replace these surfaces completely or partly with a surface the water can penetrate. For example, you can use different sizes of gravel or shingle, granite chippings, rock flour or similar.

Another option is to use permeable paving, allowing the water to seep through and into the ground. For example, you can use special tiles with wide joints that let water drain through and into a permeable base.

You can also choose crushed stone, or grass block pavers, which are paving stones with open cells that allow grass to grow through them and water to soak into the ground. Grass pavers are available in many different types, made from concrete blocks or as plastic frames. Grass pavers are as strong and durable as regular paving stones, even though they make the paving look almost like a regular lawn.

On hard, impermeable surfaces, such as asphalt and concrete, around 100% of rainwater will usually run off, on gravel surfaces around 60% of the water will run off, while on green surfaces only 0-5% will be diverted away as runoff.

Please note that;

- there are rules for how much of your property you are allowed to pave over

- your municipality may also have rules about how to pave your driveway so that garbage collectors can easily push your garbage container, for example. Note that pea gravel, grass and grass pavers are not considered roadworthy surfaces.

A rain garden, also called an infiltration bed, not only helps you control where rainwater collects in your garden. It is also a decorative element in your garden, providing better living conditions for birds and small animals.

A common approach is to drain rainwater from the roof via a leak-proof gutter to a rain garden. A rain garden is suitable for plants that can tolerate soil conditions alternating between very moist and almost completely dry. For example, flowering plants such as yellow iris and lion's foot, ornamental grasses, and shrubs and trees such as blackcurrant, willow or birch. You can also fill the bed with stones. So, a rain garden can be created in many ways. You may want to consult a landscape gardener to find the best solution for your particular garden. 

Note that as a landowner, you must obtain an infiltration permit from the municipality before establishing a rain garden. This is because there are distance requirements to drinking water wells, and the municipality will always check if there is any information about soil contamination on your property. In several municipalities, you can be reimbursed a percentage of what you paid to be connected to the sewer system if you build a rain garden.

You can connect your rain garden to a depression in the lawn, which in turn can be connected to a dry well.

A dry well is an easy and relatively cheap way of leading rainwater away from your house. A dry well is a hole in the ground filled with gravel or stones into which rainwater is collected and held until it has infiltrated down into the ground.

There are many different types of dry well: You can either buy a ready-made 'box' or you can establish your own dry well. There are certain things to consider when installing a dry well: your dry well should be dimensioned to the water volumes it is likely to receive, and you also need to factor in the permeability of the soil.

Note that as a landowner, you must obtain a permit from the municipality before establishing a dry well.

As mentioned above, you need to factor in the permeability of the soil: Is the soil suitable for infiltration and is the soil infiltration rate good enough? Meeting these requirements can be especially challenging in clay soils or areas with high groundwater levels.

Green roofs are roofs planted with grass or succulents, for example. The growing medium layer can hold water. This means there will be less rainwater on your property to drain away. The ability of the growing medium to bind and retain water determines how much water needs to be diverted away from the roof and which plants can thrive there. The weight of a green roof varies with the amount of water the growing medium can retain. Make sure your roof structure can support the green roof. Moisture damage can occur if the membrane under the damp growing medium is breached, allowing water to penetrate the underlying structure.

If you are installing a green roof, make sure that the roof structure is dimensioned to support the entire roof including a water-filled growing medium and the plants growing in it. If the roof can absorb and retain a lot of water, for example in a thick layer of soil, the roof can become very heavy. It is also important to keep the damp environment separate from the rest of the building structures. A membrane is usually used for this purpose. Therefore, it is important to prevent roots etc. from breaking through the membrane. You may need to weed out and remove seedling trees. Keep the growing medium in place with a net to avoid UV degradation of the underlying membrane.

Water butts are an easy way to relieve pressure on sewers. And you can make good use of the water they collect. A water butt can collect much of the water from your downpipe. Any remaining water will flow onward into your drain and to the sewers. Most water butts can contain 200-300 litres of rainwater, but they are available with a capacity of up to 1000 litres.

You might think that rainwater is clean. But it contains a number of contaminants collected from the atmosphere and on your roof. You can use rainwater to flush toilets, wash clothes, wash your car and water your garden.  However, you must not use the water for drinking or washing, or for watering your vegetable garden if you eat the vegetables raw.

Water from a water butt may become contaminated, and if the water is exposed to light, algae can grow in it. This can cause problems with bad odours. If the water in the water butt is still, dirt and dead algae will fall to the bottom. Here it will start to rot, and the water will start to smell musty. Therefore, you should periodically empty and clean your water butt.

It is also a good idea to put a cover on your water butt. This will prevent algae from growing and mosquitoes from laying eggs in the water.

If you want to reuse rainwater on a larger scale for toilet flushing and laundry, for example, you might want to invest in a rainwater harvesting system.

Contact your municipality before installing a rainwater tank. There may be special requirements and subsidy rules where you live. And for new construction and multi-story buildings, a separate permit is required.

 Choose a tank size that suits your family's consumption and make sure the tank has both a filter and an overflow. You should inspect and clean your tank at least once a year.

A groundwater pump is placed in a pit, for example in the basement, where the sides of the pit allow water from the saturated soil to flow in. This helps to reduce the water pressure.

Note that specific soil conditions could mean that the water comes from your neighbour's property as well.

A groundwater pump should be inspected regularly.

If you have experienced basement flooding with clean water (not sewage) in the past, or if the foundation and plinth of your house are absorbing moisture, a perimeter drain may be a good idea.

A perimeter drain is like a buried gutter that runs along the foundation and outer wall of your house. It diverts excess water away from your house and directs it to a rainwater well and onward to the sewer and drainage system.

Contact your local sewer contractor if you want to install a perimeter drain.

A backflow blocker protects your house against water from the sewer during a cloudburst. On normal days, sewage water will go through the backflow blocker. During a cloudburst, the backflow blocker will close automatically so that water cannot flow into your house.

There are several types of backflow blocker for placing either inside or outside your house. A backflow blocker can prevent sewage water from running back up into your house. A backflow blocker is a section of sewer pipe with two flaps. The flaps act as a sluice that opens when sewage flows out of your home and closes if sewage water pushes in from the outside. However, if the drains in your basement are at a lower level relative to the sewers in the street, sometimes the best solution is a pump well.

Ask a plumber about which type is best for your home. Installation must be by a licensed sewer contractor. The cheapest types usually fit on the parts of the sewer system with no toilet connected. Besides this comes the cost of excavation work and repairing the basement floor, if necessary. In some cases, you may also need to modify the piping system, so that rainwater is removed behind the backflow blocker.

Inspect and clean your backflow blocker regularly to ensure there is no dirt or grime in the closing mechanism.

Note that when the backflow blocker closes during heavy rainfall, this also means that no water can flow out through the drain. This can cause problems if you have drain grates in your basement shafts, because any water that collects could then enter through the basement door.

Problems can also occur where your gutter downpipes are connected to the system before the backflow blocker. You can solve these problems by covering your basement shaft and providing an overflow option for your gutter downpipes.

In a worst-case scenario, a poorly thought-out solution can make things worse. You should therefore consider asking a licensed sewer contractor for advice.

A pump well helps get rid of sewage water, even when the sewer is full. During heavy rainfall, the pump well collects the sewage water, and you avoid flooding in your basement. 

The well is placed so that any sewage is directed towards the well. A pump in the well pumps the water onward to the sewer. Even if the sewer system is overloaded, the water can be pumped onward, and you can still get rid of your sewage water. 

Installation must be by a licensed sewer contractor.