To choose curb inlet protection, first identify whether your inlet is a curb opening, a grate, or a combination. Then measure the throat length or grate frame and match it to a device type: curb tube, curb sack, or sediment bag. Confirm the overflow relief works, and inspect often so sediment never exceeds half the device height.
The wrong device, or the wrong size, fails fast: it clogs, floods the road, or lets silt pass around it. This guide follows the order you make the decision: identify the inlet, choose a device, size it, install it, maintain it, and know when inlet protection alone is not enough.
Step 1: Identify Your Inlet Type and Measure It
Two things drive every later choice: the inlet type and its dimensions. Classify the inlet first, then measure it.
- Curb inlet (grateless curb opening). A slot in the face of the curb. Water enters from the side through the throat.
- Grate inlet (drop inlet). A grate set flush in the pavement or ground. Water drops straight through the grate.
- Combination inlet. A grate in the gutter paired with a curb opening. It needs protection that handles both entry points.
Next, note whether each inlet is on-grade (water passes by and enters in part) or in a sag (all runoff collects there). Sag inlets take the heaviest flow, so device choice and overflow relief matter most there.
Then take your measurements:
- For a curb opening, measure the throat length along the curb face and the opening height.
- For a grate, measure the frame length and width, outside edge to outside edge.
- For a combination inlet, record both the grate frame and the curb throat.
- Note whether the grate lifts out. Some devices hang beneath the grate and require removing it.
Photograph each inlet and label it on the site plan. A written list of inlet type, dimensions, and flow condition speeds up ordering and installation. Skip it and you order by guess, which is how an undersized device gets bypassed on the first storm.
Step 2: Choose Between Curb Inlet Filters, Sacks, and Inlet Protection Bags
Match the storm drain inlet filter to the inlet style first. A device built for a grateless curb opening will not seal a drop inlet, and the reverse is also true. Shortlist two or three options from the table below, then weigh the trade-offs.
| Product | What it is | Inlet style it targets | Role |
|---|---|---|---|
| Dandy Curb | High-visibility orange monofilament geotextile tube with an aggregate pouch to hold it in place | Grateless curb and median inlets | Curb inlet filter that conforms to the opening |
| Dandy Curb Sack | Two-part device: curb-facing barrier plus a sack hanging below the grate | Combination inlets with a grate | Filters at the curb and catches solids under the grate |
| Erosion EEL | Woven polypropylene tube filled with shredded recycled tire rubber | Curb and perimeter applications | Filter tube; the rubber media can be cleaned and reused |
| Inlet Pro Sediment Bags | Geotextile sediment bags in standard and high-flow configurations | Grate and drop inlets | Inlet protection bags that retain suspended solids |
| GeoHay | Sediment control logs made from recycled carpet fibers | Curb and perimeter applications | Log-style barrier that filters runoff |
Curb bag versus curb sack. A curb bag or sediment bag hangs under the grate and catches what falls through. A curb sack, such as the Dandy Curb Sack, adds a curb-facing barrier so flow is filtered before it reaches the grate. Installing and maintaining the sack means removing the grate, so confirm the grate lifts out before you choose it.
Dandy sack in context. The Dandy Curb is built for inlets without grates. For a combination inlet, the Dandy Curb Sack is the version made for it. Match the product to your inlet, not the other way around.
Proprietary versus site-built. Proprietary devices come pre-sized and tested, and some have independent lab results. Examples include the University of Illinois testing noted for the Dandy Curb Sack and Erosion EEL. Site-built options, such as stone, gravel bags, or compost logs, cost less up front but depend on crew skill and fit the opening less reliably. Check your local rules first, since some jurisdictions accept only listed products.
Reusable versus disposable. Reusable devices cost more at purchase but pay back over repeated cleanouts on a long project. The Erosion EEL's rubber media can be cleaned and reused in new units. Disposable bags suit short jobs, where cleanup labor costs more than replacement. On a project lasting many months, reusable usually wins. On a brief one, disposable often does.
When you request quotes, ask each supplier for the flow rate and soil used in any test data they cite, so you compare like with like.
Step 3: How Do You Size Curb Inlet Protection for Your Opening?
Sizing turns your Step 1 measurements into an order. A device that is too short leaves gaps at the ends, and one that is too long bunches and lifts. Size to the opening, then check the supplier's size chart.
Grateless curb opening. Match the device length to the throat length, with a small allowance at each end so the device seals against the curb and gutter. Tubes like the Dandy Curb conform to the opening, so a length that runs slightly past the throat is typical. Confirm the manufacturer's recommended overlap.
Grate inlet protection. Size to the grate frame, not the grate bars. A sediment bag such as an Inlet Pro bag must match the frame length and width so its rim sits fully on the frame. Too small, and it can slip into the inlet. Too large, and it hangs unevenly. lists both standard and high-flow configurations, so pick the one that suits expected flow.
Drop inlet protection. Treat a drop inlet like a grate inlet: measure the frame and size the bag or sack to it. Check the structure's depth too, since a bag has to hang clear of the water level below.
Worked example. Say you measure a curb opening with a 4-foot throat and a grate beside it with a 2-foot by 3-foot frame. That makes it a combination inlet.
- Record both measurements: 4-foot throat, 2-by-3-foot frame.
- Pick a combination device, such as a Dandy Curb Sack, and look up the size that covers a 4-foot throat and the 2-by-3-foot frame.
- Choose the next size up if your measurements fall between two sizes.
- Check that the grate lifts out, since the sack is installed and serviced with the grate removed.
On jobs with many inlets, order a spare unit so a damaged device can be replaced the same day.
Step 4: Install the Device and Check the Overflow Path
Install the device so it seals against the inlet and still lets water escape when the filter is full. A sealed device with no relief path sends flood water into the street.
Use this sequence:
- Clear debris from the inlet, gutter, and the pavement around it.
- Confirm the device matches the type and size you recorded in Step 1.
- For a grate-mounted sack or bag, lift the grate, seat the device on the frame, and set the grate back over it.
- For a curb tube, lay it across the throat so it contacts the curb and gutter along its full length, then place the aggregate pouch or weights.
- Stand back and check for gaps at the ends or corners. Water takes the easiest path, and any gap is a bypass.
- Pour water or wait for the first rain, then watch where the flow goes.
Verify that the device's built-in overflow features are unobstructed, so heavy rain does not flood the roadway [S2]. Never tie off, stuff, or cover relief openings to gain more filtering.
A sound curb inlet protection detail on your plans shows:
- Inlet type and dimensions
- The device model and size
- Overflow or relief feature location
- Anchoring method
- Maintenance trigger
- Traffic and pedestrian clearances
Storm drain inlet protection works only if the crew installs what the detail shows. Walk the site with the installer before the first inlet goes in.
Step 5: How Often Should Inlet Filters Be Inspected and Cleaned?
Inspect inlet protection on a fixed schedule and after every significant rain. Many permits and local rules set the interval, so check yours first. Where yours is silent, weekly checks plus a check after each storm make a practical baseline.
Sediment depth is the cleanout trigger. Remove accumulated sediment once it reaches roughly one-third to one-half of the device's height [S3]. Past that point, the device clogs, flow backs up, and water takes the overflow path carrying unfiltered sediment.
During each inspection, check:
- Sediment depth against the trigger
- Tears, holes, or loose seams
- Gaps at the curb, frame, or ends
- Overflow features that are blocked
- Displaced or missing anchoring weights
Keep expectations realistic. Florida DOT data show properly maintained inlet protection removes 25 to 35 percent of total solids from incoming flows and 15 to 25 percent of nutrients, per the Minnesota Stormwater Manual. Those are generic figures for properly maintained devices, not a rating for any product named here. Inlet protection is a last line of defense, not a substitute for controls upstream.
Read the test conditions behind any efficiency claim. University of Illinois researchers evaluated inlet protection using a simulated discharge rate of 119 gallons/minute in a 2016 study. That is a lab condition, not a performance rating, so field results will differ. Ask any supplier what flow rate and soil their numbers came from.
In cold weather, frozen sediment is harder to remove and ice can block relief openings. Where snowplows run, blades can catch tubes, logs, and exposed edges, so check for displacement after every plowing. Plan cleanouts before a freeze, and don't pile plowed snow over inlets.
When Is Curb Inlet Protection Legally Required?
Inlet protection is typically required when construction runoff can reach a storm drain. The federal Clean Water Act mandates sediment control measures for construction projects that disturb more than 0.4 ha of soil, per a 2024 paper in the Journal of Environmental Management. Treat that as a federal reference point, not the only trigger. State and local thresholds can be lower, so confirm yours before you start grading.
Under the NPDES construction permit program, sites above the threshold need a stormwater pollution prevention plan (SWPPP). The SWPPP lists the controls on the site, including inlet protection, and where they go. Inspectors compare what is installed against that plan, so your inlet list and curb inlet protection detail should match what is in the ground.
Storm drains clog and carry pollutants even in ordinary conditions. The Philadelphia Water Department reports about 72,000 stormwater inlets in the city that are susceptible to clogging from street debris (2026, per The Philadelphia Inquirer). A construction site that adds sediment to that load draws attention fast.
Before you order, check your own state or local approved product list. Some agencies accept only listed devices, and the best curb inlet protection for your job is one that fits your inlet, meets that list, and satisfies your permit. Ask your plan reviewer or permit office which products qualify and what inspection records they expect.
When Inlet Protection Needs Silt Fence and Site-Wide Erosion Control
Inlet protection is the last line of defense, not the first. It works best behind perimeter silt fencing, stabilized bare soil, and other site-wide controls that keep sediment from reaching the street. If your site also needs seeding or soil stabilization, FL Hydroseed covers that side of erosion control.
Prices and plan limits verified as of November 2026.
FAQs
What is the difference between a curb bag and a curb sack?
A curb bag, or sediment bag, hangs under the grate and catches what falls through. A curb sack adds a curb-facing barrier, so flow is filtered before it reaches the grate. The Dandy Curb Sack is one example. It requires removing the grate for installation and maintenance, so confirm the grate lifts out before you order.
How often should inlet filters be inspected?
Follow the interval in your permit or local rules. Where they are silent, inspect weekly and after every significant rain. At each visit, check sediment depth, tears, gaps at the curb or frame, blocked overflow features, and displaced anchoring weights. Remove sediment once it reaches about one-third to one-half of the device's height [S3].
Which curb inlet protection has the best sediment removal efficiency?
No single product can be named from the data available here. Florida DOT figures show properly maintained inlet protection removes 25 to 35 percent of total solids, but that is a generic range, not a product rating. Some devices have independent University of Illinois testing. Ask suppliers for test data, including flow rate and soil used.
Can curb inlet protection be used on both sag and on-grade inlets?
Yes, but the demands differ. An on-grade inlet sits on a slope, and water passes by and enters in part. A sag inlet sits at a low point and collects all runoff, so it sees heavier flow and ponding. Choose a device sized for that flow, and confirm overflow relief stays unobstructed [S2].
How do you handle inlet protection in cold weather or where snowplows run?
Frozen sediment is harder to remove, and ice can block relief openings, so schedule cleanouts before a freeze. Snowplow blades can catch tubes, logs, and exposed edges, so check for displacement after every plowing. Do not pile plowed snow over inlets, since that blocks flow and hides the device from inspection.
Are reusable inlet filters worth it compared to disposable ones?
On a project lasting many months, reusable devices usually win, since the higher purchase cost is spread across repeated cleanouts. The Erosion EEL's rubber media can be cleaned and reused in new units. On short jobs, disposable bags often make more sense, because cleanup labor can cost more than replacement.
Conclusion
The right curb inlet protection comes from the order of your decisions: classify the inlet, measure it, match a device type to that inlet, then confirm the overflow path works. Keep in mind that even a well-chosen device removes only part of the solids reaching it, so it cannot make up for bare soil upstream.
Before you order, list each inlet with its type and dimensions, and check your state or local approved product list. Then set a cleanout trigger at one-third to one-half of the device's height and write it into your inspection routine.