WINKLER makes textile filters that hold solids back at the point where rain or surface water enters something: a storage tank, a soakaway, a road gully or a site drainage system. A surface water filter in this sense is a component in a drainage system, not a water treatment device. Four different jobs, four different places, and the filter that suits one is rarely the filter that suits another.
Rainwater tank inlet filter bags DN325 to DN800 · soakaway filter bags DN1000 to DN2500 · gully filter inserts in 100 or 70 µm · plastic pellet retention systems in 70 µm
What decides the choice is not the filtration rating. It is the position, the existing geometry, the hydraulic load and the kind of solids arriving. A finer filter in the wrong place performs worse than a coarser one in the right place.
These are two different starting points, and the fastest route through this category is to know which one you are on.
Rainwater harvesting means water you intend to keep and use. A rainwater harvesting filter here protects the storage and everything downstream of it: pumps, drip lines, irrigation. The relevant products are the tank inlet filter bag and, where infiltration is part of the scheme, the soakaway bag.
Stormwater drainage means water you intend to get rid of, cleanly. Here the filter protects the receiving system: the sewer, the watercourse or the infiltration structure. The relevant products are the gully bags and the pellet retention systems.
Some schemes are both, and the products combine without difficulty. But the vocabulary, the decision criteria and usually the buyer are different, so the rest of this page is organised that way.
Rainwater tank inlet. A textile filter bag hangs inside the tank directly under the inlet, held by six straps at the existing opening. It is a rainwater sediment filter in the practical sense: what would otherwise settle on the tank floor is caught where you can reach it. Six sizes, DN325 to DN800, washable and reusable.
Soakaway. A soakaway loses capacity when fine material settles on the infiltration surface and closes the pores. A two-layer bag inside the chamber catches that material before it reaches the base, so the bag is changed instead of the soakaway. Four sizes, DN1000 to DN2500, single use, with a separate mounting kit for concrete and masonry chambers.
Where to put which filter in a rainwater catchment, and how the bag compares with downpipe and vortex designs, is set out on the application page.
General solids retention. A single-layer gully bag at nominal 100 µm goes into the existing catch basket and adapts to its shape. It holds sand, grit, sediment, leaf fragments and the general debris a surface delivers after rain. This is the version to standardise on across a stock of gullies.
Finer road-borne particles. A two-layer bag at nominal 70 µm for locations where finer retention is the specific objective, including tyre wear particles. Lengths from 0.49 to 0.84 m to suit gully pot forms A4, B1, C3, D1 and yard gullies.
Both are storm drain filter inserts in the sense that they retrofit into what is already installed. Neither is a treatment plant with a demonstrated removal efficiency, and neither is presented as one. The comparison and the selection logic are on the application page.
Sites that handle plastic pellets, flakes or regrind lose material at transfer points, and the nearest drain is where it leaves. Retention systems consist of a galvanised bucket and a pre-fitted textile insert at nominal 70 µm, in five forms from Ø 260 to Ø 395 mm.
Selection follows the gully pot geometry rather than the capacity: two of the five forms hold almost the same volume and are not interchangeable. Replacement inserts are available separately.
Both figures describe a nominal filtration rating, which is how the material is designed rather than a measured separation limit. Actual retention and actual flow depend on particle shape, on how loaded the filter already is, on the installation and on the operating condition.
One consequence is worth carrying into every selection on this page: a finer filter is not automatically the better choice. As loading increases, so does the maintenance requirement and the risk of restricted flow. Choosing a rating means choosing a servicing regime at the same time.
Many products are available in standard sizes and can be ordered directly. For chambers, buckets or inlet situations that differ, WINKLER manufactures technical textile filters to measure. For an assessment we need dimensions, photographs or drawings, the installation position, the expected water load and the type of solids.
Position decides. A tank inlet takes an inlet filter bag, a soakaway takes a chamber filter, a road gully takes a gully bag in the catch basket. For plastic pellets the gully pot form has to match as well.
It varies by product. The tank inlet filter is washable and reusable. The soakaway bag and the general gully bag are planned as consumables. Pellet retention inserts are changed on condition.
Yes. We need dimensions or drawings, photographs of the installation, details of the fixing, the expected water load and the type of solids.
It is the nominal rating, the design figure for the material. What is actually retained depends on particle shape, water load, how loaded the filter is, the installation and its condition.
No. A product can be a technical measure within a wider scheme. What a scheme achieves depends on the installation, the hydraulics, the maintenance and the evidence, and on the requirements that apply to the project.
Praxisbeispiele, Auswahlhilfen und technisches Wissen für die passende Einordnung der Produkte dieser Kategorie.
Application Updated: August 2026Reading time: approx. 3 minutes Anyone planning a rainwater harvesting scheme, or trying to fix one that silts up, reaches the same...
View application →Application Updated: August 2026Reading time: approx. 3 minutes Road, yard and car park gullies share a construction: a grating, a catch basket beneath it, then...
View application →Soakaway clogging ➔ causes, how to size the chamber filter and how a filter bag cuts solids ingress. Read the guide now!
Read guide →Your cart is currently empty.
Start Shopping
