Choosing the best storm drain curb inlet filter starts with matching it to your drain’s shape and size. Some models sit over an open curb inlet, while others strap around a grate or fit inside an inlet opening. The right option can help capture sediment and debris while allowing stormwater to keep flowing—but no filter should be treated as a substitute for checking and maintaining the drain.
Table of Contents
Quick Comparison
| Product | Mounting style | Key details | Best suited for |
|---|---|---|---|
| PIG Open Curb Inlet Filter | Over an open curb inlet | Wedge-shaped; 34 inches long; adjustable to 4 or 5 inches high | Open inlets and sediment capture |
| PIG Grate-Mount Curb Inlet Filter | Straps around a grate | Designed to cover 48-inch drains; reusable fabric filter | Grated curb drains and floating debris |
| ENPAC Storm Sentinel Curb Inlet Filter | Over a curb inlet | Rigid coiled center; standard size is 48 inches long and 5 inches in diameter | Capturing sediment and debris at varied sites |
| ENPAC 4346 Storm Sentinel Insert | Fits inside the inlet opening | Adjusts for openings from 24 to 30 inches; up to 500 GPM overflow rate | Inlets needing an adjustable sediment insert |
| ENPAC 4346-IB Storm Sentinel Insert | Fits inside the inlet opening | Adjusts for openings from 24 to 30 inches; includes an indicator packet for hydrocarbons | Sediment capture with fuel and oil indication |
Our Picks: Best Storm Drain Curb Inlet reviews
1. PIG Open Curb Inlet Filter: A Low-Profile Pick for Open Drains
This PIG filter is made to sit over an open curb inlet rather than wrap around a grate. Its wedge-shaped profile is designed to lie flat, and the frame can be oriented to set the height at 4 or 5 inches. Measure the opening before choosing it: the filter is 34 inches long, so it is not a one-piece solution for every curb drain.
High-flow fabric lets water pass through while the filter captures sediment. PIG lists a sediment-removal efficiency of 82.4%. Hook-and-loop strips allow you to connect filters side by side, and attached bags can be filled with bricks or gravel to add weight. The reusable design is intended to be rinsed and put back in place.
This is a focused option for users who need a compact filter over an open inlet and want to connect units for a longer opening. It is less suitable for a drain that has a grate requiring a strap-mounted cover. The stated efficiency is a product specification, not a guarantee of the results you will get in every flow or site condition.
Pros:
- Adjusts between 4- and 5-inch height by changing the frame orientation
- High-flow fabric is designed to pass water while capturing sediment
- Hook-and-loop strips let you connect filters for longer inlets
- Reusable and can be weighted with bricks or gravel
Cons:
- Its 34-inch length may not cover a longer inlet on its own
- Designed for open curb inlets, not for mounting around a grate
Verdict: Choose the PIG Open Curb Inlet Filter if you have an open curb drain that fits its dimensions and want a reusable, connectable sediment filter.
2. PIG Grate-Mount Curb Inlet Filter: A Strap-On Cover for Grated Drains
This flat-panel PIG filter is designed for curb drains with grates. A strap-and-buckle system wraps it around the grate, giving it a different mounting approach from filters that simply rest over an open inlet. The listed size is 55.125 inches long, and the product is sized to cover a 48-inch drain with a 3-inch overlap on each side.
The fabric is designed to let water pass while catching sediment and floatable debris such as trash and yard waste. The listed sediment-removal efficiency is 35%. The product description also notes that its 6-inch height can cover a range of curb-drain heights; on taller drains, the exposed top portion acts as an overflow port. Multiple units can be placed side by side to cover longer openings.
The strap mounting makes this a sensible choice when the grate is part of the installation, but that same design means it is not the best match for an ungrated opening. Check the drain length and available attachment points before ordering. As with other filters, inspect it regularly so collected debris does not interfere with water flow.
Pros:
- Strap-and-buckle system is designed for mounting around a grate
- Specified to cover 48-inch drains with overlap at both ends
- Made to capture sediment and floating debris
- Reusable fabric can be rinsed and returned to service
Cons:
- Requires a compatible grate for its mounting method
- Its stated sediment-removal efficiency is lower than the other PIG filter listed here
Verdict: Pick this model when you need a reusable filter that straps around a compatible curb-drain grate, especially for a drain close to the specified coverage length.
3. ENPAC Storm Sentinel Curb Inlet Filter: A Flexible, Reusable Barrier
The ENPAC Storm Sentinel is a curb-inlet filter with a rigid coiled center. The design is intended to catch sediment, trash, and debris while letting stormwater pass through. Its standard size is 48 inches long and 5 inches in diameter, and custom sizes are available according to the product description.
Installation uses a hook strap and does not require special tools. Optional weights can help hold the filter in place, and the product description says those weights also absorb a small amount of hydrocarbons. The filter can be reused until it is full and no longer filtering water. A version with oil-absorbing packets is described as having a 0.28-gallon absorption capacity.
This model may suit residential or industrial locations where a flexible, removable barrier is preferred. It can also be combined with catch-basin inserts, though the two products serve different points in a drainage system. The listing does not provide a single universal fit size beyond the standard dimensions, so confirm the curb opening and attachment arrangement before buying.
Pros:
- Rigid coiled center is designed to capture pollutants while allowing water to pass
- Hook-strap installation requires no special tools
- Optional weights can help secure the filter
- Standard and custom sizing options are described
Cons:
- Standard length may not suit every inlet without a size check
- Needs inspection and replacement or servicing when full
Verdict: Consider the ENPAC Storm Sentinel if you want a reusable curb-inlet barrier with a coiled center and a strap-based installation, and can confirm the fit for your opening.
4. ENPAC 4346 Storm Sentinel Insert: Adjustable Sediment Control
Unlike the filters that sit over an inlet, the ENPAC 4346 is an insert made to fit inside curb openings from 24 to 30 inches. It requires no special tools to install, which may make it a practical option for sites where an internal insert is a better fit than an exterior filter.
The listed overflow rate is up to 500 gallons per minute, a feature intended to help avoid ponding as water passes through the system. The insert is described as a sediment model and does not include the hydrocarbon-indicator packet listed for the 4346-IB. Its fit range is specific, so measure the opening carefully rather than assuming it will work with a larger or smaller inlet.
The stated overflow capacity is a product specification, not a promise that a drain will never pond. Actual flow depends on site conditions and whether the insert is clear and correctly installed. For projects with stormwater-plan requirements, the manufacturer says the insert can help comply with NPDES requirements when used as a Best Management Practice; confirm requirements with the responsible project or local authority.
Pros:
- Adjusts to fit curb inlet openings from 24 to 30 inches
- Installs without special tools
- Listed overflow rate is up to 500 GPM
- Provides a sediment-focused insert option
Cons:
- Fit range is limited to openings from 24 to 30 inches
- Does not include the hydrocarbon indicator described for the 4346-IB
Verdict: Choose the ENPAC 4346 if your inlet falls within its stated size range and you need an internal sediment insert without a hydrocarbon-indicator feature.
5. ENPAC 4346-IB Storm Sentinel Insert: Sediment Capture with an Oil Indicator
The ENPAC 4346-IB shares the core fit and installation details of the 4346: it adjusts for curb inlet openings from 24 to 30 inches and requires no special tools. It is intended to capture sediment, with an added Imbiber Beads indicator packet for hydrocarbons.
The packet is described as capturing and containing gasoline, diesel, fuels, and oils, and changing color to indicate hydrocarbons in stormwater runoff. The product also lists an overflow rate of up to 500 gallons per minute. That combination makes it a more specialized choice than the sediment-only 4346, but it still depends on correct sizing, installation, and routine checks.
The indicator is useful as a signal that hydrocarbons may be present; it should not be treated as a complete spill-response system or as proof that runoff is safe. If you only need sediment filtration, the standard 4346 is the simpler match. If you need the added indicator function, check the product details and your site requirements before selecting this version.
Pros:
- Fits the same stated 24- to 30-inch opening range as the sediment-only insert
- Includes an indicator packet for specified fuels and oils
- Indicator changes color when hydrocarbons are present
- Listed overflow rate is up to 500 GPM
Cons:
- Costs and care requirements may be greater than a sediment-only setup
- The indicator packet does not replace spill response or site-specific testing
Verdict: Select the ENPAC 4346-IB over the standard 4346 when the hydrocarbon indicator is a useful part of your stormwater monitoring plan and the inlet fits its size range.
How to Choose a Storm Drain Curb Inlet Filter
Match the Filter to the Drain Style
First identify whether you have an open curb inlet, a grated drain, or an opening that can accept an internal insert. The PIG Open Curb Inlet Filter is designed to sit over an open inlet, while the PIG Grate-Mount model uses straps around a grate. The ENPAC 4346 and 4346-IB fit inside a specified curb opening. A filter with the wrong mounting style may not sit securely or cover the drain as intended.
Measure the Opening and Check Coverage
Measure the drain’s length, height, and opening width, then compare those figures with the product dimensions and stated fit range. The PIG open-inlet filter is 34 inches long, and the grate-mount model is sized to cover a 48-inch drain. The ENPAC insert models fit openings from 24 to 30 inches. If the inlet is longer than a single filter, look for a product designed to connect or place units side by side, and confirm how much overlap is needed.
Decide What You Need to Capture
Some products focus on sediment, while others are also intended to catch floating debris or provide an indicator for hydrocarbons. The PIG grate-mount filter is described as capturing items such as trash and yard waste. The ENPAC 4346-IB adds an indicator packet for specified fuels and oils. Choose based on the pollutants you need to manage, and do not assume a sediment filter also handles oil unless the product details say so.
Balance Water Flow and Filtration
A curb inlet filter needs to let water pass while trapping some of the material carried in runoff. Compare the listed flow-related features, such as the ENPAC inserts’ stated overflow rate, and consider how quickly the drain may receive water. A filter can collect debris and need cleaning; check it during use, particularly after conditions that carry sediment or floatables. Do not rely on a product specification as a guarantee against ponding at your site.
Consider How It Will Stay in Place
Mounting methods vary. One PIG filter has attached bags that can be filled with bricks or gravel, the grate-mount PIG uses straps and buckles, and the ENPAC Storm Sentinel uses a hook strap with optional weights. Choose a secure method that suits the inlet and the site. Make sure added weight or straps do not block the opening or create a hazard.
Plan for Cleaning, Inspection, and Replacement
Reusable filters still need attention. The PIG models are described as rinse-and-reuse products, while the ENPAC Storm Sentinel is reusable until it is full and no longer filtering water. Set a maintenance routine that fits your site, and inspect the installation for collected material, shifting, or signs that water flow is restricted. Follow the product instructions for cleaning and any replacement parts or indicator packets.
Frequently Asked Questions
What is a storm drain curb inlet filter?
It is a device placed over, around, or inside a curb drain to capture some sediment, debris, or other listed pollutants before runoff enters the drainage system. The design and pollutants it handles depend on the specific product.
How do I know which mounting style I need?
Look at the inlet itself. An open curb opening may suit an over-the-drain filter, a grate may work with a strap-mounted cover, and some openings can take an internal insert. Check the product’s installation details and measure before ordering.
Can one filter cover a long inlet?
That depends on the product. The PIG Open Curb Inlet Filter has hook-and-loop strips for connecting filters, and the PIG Grate-Mount model can be placed side by side. Confirm the coverage and overlap needed for your drain rather than relying on the product name alone.
Do storm drain filters stop flooding?
No filter can guarantee that a drain will not flood or pond. High-flow fabric and listed overflow features are designed to help water continue through, but performance depends on the drain, flow conditions, installation, and how much debris has collected.
How often should I clean or inspect a curb inlet filter?
Follow the product instructions and check the filter often enough to spot buildup, shifting, or reduced water flow. The right schedule depends on site conditions and how much sediment or debris reaches the drain.
What is the difference between the ENPAC 4346 and 4346-IB?
Both are adjustable inserts for 24- to 30-inch curb openings, with a listed overflow rate up to 500 GPM. The 4346 is the sediment model. The 4346-IB adds an indicator packet described for capturing and signaling the presence of certain hydrocarbons.
Final Recommendation
For an open curb inlet, the PIG Open Curb Inlet Filter stands out for its adjustable height, connectable design, and stated sediment-removal efficiency. Choose the PIG Grate-Mount model when your drain has a compatible grate and you want a strap-on cover. For an internal insert, the ENPAC 4346 suits sediment control, while the 4346-IB adds a hydrocarbon indicator. In every case, measure carefully, match the mounting style, and plan to inspect the filter so it can keep doing its job.
