Downpipe filter for your rainwater system
Even before the water reaches the rain barrel or cistern, it is cleaned of leaves and dirt in the downpipe filter.
For this purpose, the downpipe filter is inserted directly into the downpipe and connected to the rainwater storage tank.
Below you will find our downpipe filters. Feel free to take a look around!

How it works the WISY downpipe filter
While coarse leaves, foliage or similar impurities fall down the centre of the downpipe, water flows down the inner walls of the pipe. In the WISY downpipe filter, the rainwater is deflected sideways by means of adhesion force and directed to the rainwater storage tank.
The dirt continues to fall down wards and is ejected there or flushed directly into the sewer. Clogging of the downpipe filter is excluded, as the inner diameter does not narrow at any point in the filter. For dirt, the downpipe filter therefore simply behaves like a piece of pipe.
Product information
Filter collector FS
The FS filter collector filters the rainwater directly in the downpipe while it is still being drained off to the side of the cistern. Its filter insert consists of fine stainless steel mesh with a mesh size of only 0.28 mm. This reliably separates leaves, moss and other washed-in debris and flushes them downwards into the receiving water.
Important details
Product information
Rain collector RS
The RS rainwater collector is installed in the vertical downpipe. It filters the rainwater flowing in from above before it drains it off to the side of the cistern. Leaves, moss and other debris are separated by the rain collector and flushed downwards into the receiving water.
Important details
Product information
Garden rain collector
The garden rainwater collector is installed in the vertical downpipe. It filters rainwater flowing in from above before it is drained off to the side of the cistern. Due to its design, it is particularly low-maintenance: leaves, dirt and other washed-up debris fall through it and are flushed down into the drain.
Important details
Product information
RainCatcher RC
The RainCatcher RC is installed in the vertical downpipe. It directs the rainwater flowing in from above to the side of the cistern. Due to its special design, the RainCatcher RC separates coarse soiling such as leaves or moss and flushes them through the downpipe directly into the drain or soakaway. The collected rainwater is very suitable for garden irrigation.
Important details
Product information
Standpipe filter collector STFS
The standpipe filter collector is both a standpipe and a filter collector. It filters rainwater flowing in from above before it is drained off to the side of the cistern. Its filter insert consists of fine stainless steel mesh with a mesh size of only 0.28 mm. This reliably separates leaves, moss and other washed-in debris and flushes them downwards into the receiving water.
Important details
Why a downpipe filter is important
Without a downpipe filter, dirt particles can get into the rainwater storage tank. These are often leaves from trees, moss from the roof or dead insects. Normally, this is organic material that decomposes over time and becomes a nutrient for microorganisms.
As in a pond with too high a nutrient input, this, in combination with a lack of oxygen, can lead to unpleasant odours. Coarse contamination can also block the tap or damage a pump.
A downpipe filter protects you from all this: it removes organic substances from the rainwater before they reach the rainwater barrel or rainwater storage tank.


WISY downpipe filter, rain flap or leaf separator?
In the past, a simple rain flap or occasionally a leaf separator was often used to collect rainwater. However, a downpipe filter is far superior to both.
We will inform you about the advantages of the downpipe filter compared to leaf separators or rain flaps at WISY.
Downpipe filter vs. rain flap
The open rain flap diverts the entire flow of water with all its impurities and allows the rainwater to splash into the container until it overflows. Only when the rain flap is closed manually does the inflow into the water tank stop. If the rain flap is forgotten to open again after the water has been removed, it will remain empty during the next rain shower.
The rain flap is also mostly used in combination with open catchment tanks or rain barrels, which have their own disadvantages and risks. Only in passing should we mention the additional dirt input and the considerable danger for playing children.
Downpipe filter vs. leaf separator
Although the leaf separator can deflect very coarse debris towards the front, it directs the flow of water downwards, even if the connected rain barrel is already full. The adhesive force of the water remains completely unused with the leaf separator and can even lead to an unintentional excessive amount of water being ejected to the front instead of being directed to the rainwater storage tank.
With downpipe filter the bin does not overflow
If the rain barrel is full, the water is diverted downwards in the correctly installed downpipe filter so that the barrel cannot overflow. With both the rainwater flap and the leaf separator, on the other hand, a full rainwater barrel would overflow because there is no hydraulic coupling of the water level between the rainwater storage tank and the downpipe filter.

Downpipe filter
for each downpipe
Diameter of downpipe and downpipe filter
The diameter of the downpipes is determined by the planner in such a way that rain falling on the roof surfaces can always run off. Like the downpipes, the downpipe filter must also be sufficiently large so that it does not become an obstacle during heavy rainfall.
The applicable standard for rainwater harvesting systems defines that there must be no constriction at any point in the rainwater filter, as otherwise leaves can collect here and a backwater can form. This rule also applies to downpipe filters.
To ensure that you always find the right downpipe filter, WISY offers several variants of each downpipe filter for different pipe diameters. In this way, you can find the right model for all common downpipes so that the downpipe filter and downpipe do not become clogged.
What is important when installing the downpipe filter?
In order to achieve an optimal water yield, the downpipe end coming from the top is flanged slightly outwards before the downpipe filter is inserted. For professionals, flanging means filing and slightly widening the upper end of the downpipe. This is easy to do even for non-professionals and is most easily done with a file.
In this way, the water coming from the top continues to flow along the inner wall of the pipe when it enters the downpipe filter without jumping into the middle of the pipe.
Secure advice now
for downpipe filter and rainwater system
If you are unsure about the choice of downpipe filter or have questions about your planned rainwater system, we will be happy to help you make the right choice.
As an experienced manufacturer for all components of a professional rainwater harvesting system, selecting the right downpipe filter is part of our daily business. Please do not hesitate to contact us.
Our friendly and competent staff will be happy to assist you in finding the right downpipe filter. We look forward to your enquiry and to welcoming you to WISY soon.