Wesnoy 1 Pcs Silt Bags for Dewatering Filter Bag Non Woven Geotextile Fabric Oil Sludge Sediment Filter Bags for Construction, Black

Why I reached for this bag

On muddy jobs where we’re trying to move water without moving the mess along with it, I like having a simple, durable dewatering bag in the truck. The Wesnoy dewatering bag is a no-frills, 5-by-15-foot nonwoven geotextile bag that promises to catch silt, sediment, and some oil while letting water seep out at a controlled rate. I used it on a couple of small site dewaters and a post-storm pool drain to see where it shines—and where it doesn’t.

Setup and first impressions

This is a straightforward piece of kit: a large, black nonwoven bag with an inlet sleeve that will accept up to a 4-inch discharge hose. No cinch rope or straps are included, so bring your own. I used a 1-inch cam strap for the 2-inch pump and a pair of ratchet straps for the 3-inch hose. The fabric feels like a mid-weight nonwoven—pliable with a bit of stretch, not the stiff, heavy stuff you see in premium, reinforced bags.

Placement matters. I got the best results setting the bag on a flat area with a slight fall, on top of a layer of landscape fabric and a pad of sand to cushion against any sharp aggregate. The exfiltration footprint expands as the bag swells, so give yourself space and keep it away from trenches or erodible slopes. I prefer to lay the bag lengthwise in the direction of flow and keep the inlet as centered as possible to avoid concentrating stress on one seam.

How it performed with silt and fines

My first job was dewatering a turbid excavation with a 2-inch semi-trash pump throttled to roughly 60–80 gpm. The bag did what I want a bag to do: it breathed steadily, visibly captured suspended fines, and put out water that was notably clearer within the first few minutes. The first flush was cloudy (as expected), then settled into a consistent, slow seep that you could watch spread through the geotextile. The outflow wasn’t drinking-water clear, but it was clear enough to meet typical BMP expectations on a small site: no plumes, no visible suspended sediment moving off site.

On a second run, I used it to drain a murky pool after a storm. Same 2-inch pump, a bit of leaf litter in the mix. The bag trapped the leaves quickly and slowed the flow, but it never plugged completely. After about 45 minutes, I shook the inlet area gently to redistribute the mat of captured debris and regained some flow. Again, the effluent quality improved markedly compared to a straight discharge.

Oil and sheen

Nonwoven geotextile will adsorb some free oil, but it’s not a dedicated oil-only filter. I tested with slightly sheened water pulled from a sump with hydraulic drip. The bag reduced the sheen noticeably, especially at the start, but it did not eliminate it. If you have a meaningful oil risk, you’ll want to supplement with booms or absorbent socks upstream of the bag. Think of this as a sediment-first solution with incidental oil reduction, not a comprehensive oil filter.

Flow rate and hydraulics: where you need to be careful

Although the inlet can physically accept up to a 4-inch hose, that shouldn’t be confused with a flow rating. Bag performance is governed by fabric permeability, the size of the bag, and how quickly it can relieve internal pressure through the surface area. If you push too much water, the bag will balloon, seams will be stressed, and you’ll either force a blowout or force bypass at the inlet.

Here’s what I saw:
- With a 2-inch pump throttled to 60–80 gpm, the bag handled continuous flow for over two hours without drama. It built up and relaxed cyclically, as expected, with a stable seepage pattern.
- With a 3-inch trash pump idling at roughly 90–120 gpm, the bag pressurized quickly. Even with a cushioned base and centered inlet, I saw concentrated stretching near the top seam and a pinhole appear after about 35 minutes. That pinhole turned into a small tear when pressure pulsed during pump restart.

After that, I made three adjustments that kept the bag intact under higher flow:
1. Split the discharge with a Y fitting into two smaller hoses and alternated between two bags. This halves the pressure per bag and makes a big difference.
2. Throttled the pump back further (you don’t have to move water as fast as the pump can deliver).
3. Buried the bag’s belly very lightly in a shallow sand bed to increase contact area and reduce ballooning.

Even with those adjustments, I consider this bag a better fit for light-to-moderate flows than for aggressive 3-inch or 4-inch continuous pumping.

Durability and construction

The seams are straight and consistent, and the fabric is uniform. It’s not a reinforced bag, though. On sharp gravel or angular crushed stone, you’re asking for trouble. Put down a sacrificial layer—old geotextile, a tarp, or sand. Most damage I’ve seen with dewatering bags happens at stress concentrators: the inlet collar (if cinched too tight on the hose and not evenly supported) and the seam nearest the bulge.

A few practical tips from my use:
- Use a wide strap or rope and spread the load around the inlet sleeve. Narrow zip ties bite into the fabric.
- Avoid running the inlet hose deep into the bag; insert just a few inches and secure. A deep insertion focuses jetting and can scour a weak spot inside.
- Don’t drag the bag once it’s loaded. It will abrade quickly. Move it empty.
- Cycle the pump if the bag starts to look like a beached whale. Give it time to bleed off pressure.

If treated with that care, the bag will survive multiple uses at lower flow. After a few runs, mine showed staining and a bit of fuzzing at the inlet but no seam separation.

Size and capacity

At 5 by 15 feet, this bag offers a generous filtration area compared to the compact 3-by-6 options. That surface area helps keep exfiltration rates up and internal pressure down—within reason. On softer soils, the footprint spreads and acts like a slow leach field. Plan your laydown accordingly and protect downstream areas from minor ponding. The large size also makes it practical to park a small skid steer bucket or wheelbarrow under the outflow area if you want to capture any sloughing fines during the first few minutes of operation.

Usability and logistics

It’s sold as a single bag with no accessories, which is fine for crews who already carry straps and fittings. I’d still love to see a simple sewn-in webbing belt at the inlet. The black fabric hides staining and looks tidy on site. Cleanup is just a matter of letting it drain, then lifting the bag’s edges to concentrate the captured sediment for disposal. If you plan to reuse it, let it dry fully; dried sediment cakes will knock loose more easily.

Where it fits in a BMP plan

As part of a reasonable BMP stack—silt fence or wattles at the perimeter, inlet protection, and common-sense site housekeeping—the Wesnoy bag adds a useful, mobile filtration step. It’s best for:
- Small to medium sump dewaters
- Pool and pond drawdowns
- Trench or utility pit dewatering
- Emergency storm cleanup where you can throttle flow

It’s less suited to high-volume, sustained pumping with big trash pumps unless you divide the flow among multiple bags and manage pressure closely.

What could be better

• Reinforcement: A heavier fabric option or double-stitched seams at the long edges would give more margin at higher flows.
• Inlet hardware: Including a simple cinch rope or webbing strap would reduce user error and protect the sleeve.
• Guidance: A published indicative flow range would help match pumps to the bag. “Fits up to a 4-inch hose” isn’t the same as “run your 4-inch pump wide open.”

The bottom line

The Wesnoy dewatering bag is a functional, budget-minded sediment control tool that works well within its lane. With 2-inch pumps and throttled flow, it produces clearly improved effluent, handles typical jobsite fines, and holds up if you cushion it and avoid over-pressurizing. Push it with higher flow from a 3-inch trash pump, and you’re flirting with seam stress and potential tears unless you split the discharge and take pressure off the fabric.

Recommendation: I recommend the Wesnoy dewatering bag for light to moderate dewatering tasks where you can control flow and prep the laydown area. It’s a solid addition to the truck for small site work, utility pits, and post-storm cleanup. If your use case relies on sustained, high-flow pumping from 3- to 4-inch trash pumps, look for a heavier, reinforced bag or plan on running multiple bags in parallel to keep internal pressure in check.