Weep hole filters, decision by decision. How to choose the right maintainable unit for a job: size, housing, valve configuration, and filter fabric, matched to the wall, the water, and the backfill.
How JET Filter™ works: visit our Product Comparison Guide.
Picking the right weep hole filter comes down to four choices: size, housing, valve, and fabric.
Each one is driven by the structure, the water it holds back, and the backfill behind it. This guide walks all four so you can spec or order the right JET Filter™ unit the first time, then maps the common applications to a starting configuration.
4 sizes
2.5 inch ABS, 3 to 6 inch stainless
+92%
flow rate vs. 4″ weep hole
2.7x
filter surface area vs. 6″ weep hole
100+ yrs
316L housing service life
Weep Hole Filters: Four Decisions, One Unit
Every JET Filter™ selection runs through the same four choices. Weep hole filters differ on size, housing, valve configuration, and fabric, and on nothing else. The sections below take them in order.
The Selection Path
Size. 2.5, 3, 4, or 6 inch, set by required flow and drain spacing.
Housing. 316L stainless steel, the standard for durability and compliance. (Not available for 2.5 in. unit)
Valve. Standard open end or a check valve, set by backflow and tidal conditions.
Fabric. The woven geotextile cartridge, set by the backfill.
Decision 1: Size
Weep hole filters from JET Filter™ come in four sizes: a compact 2.5 inch ABS, plus 3, 4, and 6 inch stainless. Bigger units move more water and relieve pressure over a wider area, which lets you space drains farther apart and use fewer of them. Match the size to the flow your design calls for and the spacing in your plans.
Conical weep hole filters also put far more filter fabric in contact with the backfill than a flat weep hole, up to 2.7x the surface area. In University of Missouri testing, a 6-inch maintainable drain produced about twice the outflow of a 6 inch conventional weep hole, with the advantage largest at the bigger sizes.
| Model | Size | Flow Rate (2.5 PSI) | vs. Traditional | Surface Area | Maint. Interval |
|---|---|---|---|---|---|
| JF3SS | 3″ | 52.2 GPM | +35% | 17.44 in² (2.47x) | 3–5 Years |
| JF4SS | 4″ | 121.9 GPM | +92% | 26.03 in² (2.07x) | 4–7 Years |
| JF6SS | 6″ | 263.4 GPM | +87% | 76.95 in² (2.72x) | 6–10 Years |
| JF2.5ABS | 2.5″ | Not tested | – | 2.9 in² | Annually |
Flow rates measured at 2.5 PSI with no soil resistance, per TRI Environmental Report MAPP-LSH 2020-003. Flow multiplier and surface area shown versus a standard 2D weep hole of the same diameter. Larger drains also allow wider spacing; see the installation guide for the spacing method.
Also available, the JF2.5ABS: a compact 2.5″ unit in an ABS housing for light-duty and non-structural drainage where a smaller filter fits. Surface area 2.9 in², cartridge serviced annually. It is the one model not built in 316L stainless, and it is not flow-rated at 2.5 PSI, so size it by the application rather than the flow table above.
Decision 2: Housing
This one is easy. Standard JET Filter™ weep hole filters all use a 316L stainless steel housing. It is the right choice for marine, coastal, high moisture, DOT, and federally funded work, it is Buy America compliant with the housing built to ASTM A240 and A666, and it carries a service life of 100+ years. The cartridge and face plate are replaceable over that lifespan, so the housing is the part you install once and leave in place.
For federal work: Buy America applies to the steel housing. Request written compliance certification from the manufacturer before submittal.
Decision 3: Standard or Check Valve
Weep hole filters come in a standard open end style and a check valve style (CVLV) that prevents backflow. Use the check valve wherever water can push back through the wall: tidal zones, submerged outlets, and any condition with reverse flow. The Michigan DOT demonstration installed both open end and closed end, backflow prevention styles to confirm both configurations. A check valve model is available in each size.
Standard (Open End)
JF4SS
Check Valve (CVLV)
JF4SSCVLV
Rule of thumb: if the outlet can ever sit below the water it is draining, specify a check valve model.
Decision 4: Filter Fabric
The cartridge is replaceable, so the geotextile is the one part of weep hole filters you match to the soil rather than accept as fixed. The standard fabric is woven Mirafi® Filter-Weave FW 300, which suits clean, granular backfill. For backfill outside that range, choose a woven fabric matched to the soil: finer backfill with more fines wants a smaller opening, while cleaner backfill allows a larger opening for higher flow.
Fabric by Backfill, at a Glance
Clean granular backfill, low fines. Standard or larger opening woven fabric for maximum flow.
Moderate fines. Mid opening woven fabric to balance flow and soil retention.
High fines. Smaller opening woven fabric to hold soil, inspected more often.
Detailed criteria follow AASHTO M 288 based on the backfill fines content. Woven fabrics also hold higher flow and resist clogging better than nonwoven fabrics, which is why the cartridge uses a woven geotextile.
Matching the Unit to the Application
Weep hole filters install in a wide range of earth retaining structures and wall materials, including concrete, steel, vinyl, aluminum, composite sheet pile, MSE, and wood. The table maps common applications to a starting configuration.
| Application | Starting Configuration |
|---|---|
| Bridge abutments, wing and return walls | 316L stainless, size by flow |
| Box culverts (retrofit) | Match the existing weep hole, 3 or 4 inch |
| Retaining walls, MSE walls | 316L stainless, size and spacing by design |
| Stormwater channels, concrete lined canals | Size by flow |
| Seawalls, bulkheads (marine, tidal) | 316L stainless with check valve |
| Dam spillways | 316L stainless, size by flow |
| Underground parking garages | Size by flow |
Starting points based on documented applications and configuration logic. Final selection depends on flow, water conditions, backfill, and wall type. JET Filter™ engineering can confirm the spec for your project.
Hydrocarbon sites: where petroleum or hydrocarbon contamination is a concern, GEOJET pairs the same drainage system with media that captures oils and hydrocarbons before they reach waterways. Media replacement runs 1 to 3 years depending on loading. See the GEOJET page for details.
Standards to Verify
When you spec or accept weep hole filters, confirm they reference the right standards for the housing and the geotextile.
| Standard | What It Covers |
|---|---|
| ASTM D4491 | Geotextile water permeability (permittivity) |
| ASTM D4355 | Geotextile resistance to UV degradation |
| ASTM D5101 | Soil and geotextile filtration compatibility |
| ASTM A240 / A666 | 316L stainless steel housing |
Steel standards apply to the stainless steel housing; geotextile standards apply to the replaceable cartridge. Full test documentation is available through the Engineering Hub.
Weep Hole Filters Quick Reference
By Size
From a compact 2.5 inch ABS up to 6 inch stainless. More flow and wider spacing means a bigger unit; match size to required flow and the plan spacing.
By Water Condition
Backflow, tidal, or submerged: check valve. Gravity drainage: standard open end.
By Backfill
Clean granular: standard FW 300. Finer soils: smaller opening woven fabric.
Not Sure Which Unit Fits?
Cut sheets, CAD and STEP files, flow data, and selection support are available through the Engineering Hub at no cost.
DOT approved. Buy America compliant. US Patents #7,615,148 (open end) and #10,124,281 (check valve).