Test method and endpoint
Ask whether the result follows ISO 811, AATCC TM127 or another defined procedure. “Waterproof 10,000 mm” without a test method, test report or specimen description is incomplete.
Technical Tarp Selection Guide
Hydrostatic Head for Tarps: What 2,000 mm, 8,000 mm and 10,000 mm Mean
A hydrostatic-head rating tells you how much water pressure a tarp fabric resists in a controlled test—not how long every finished tarp will remain leak-free in every installation.
This guide helps procurement teams, tarp converters, outdoor brands and industrial buyers translate water-column numbers into a practical specification covering fabric, coating, seams, reinforcement, use conditions and test documentation.
The useful answer in one paragraph
A 2,000 mm fabric resists the pressure generated by a two-metre water column in the stated laboratory test; 8,000 mm corresponds to eight metres, and 10,000 mm to ten metres. Those figures are approximately 19.6, 78.5 and 98.1 kPa respectively. They compare the fabric's resistance to water penetration, but the finished tarp still depends on seams, welding, eyelets, edge reinforcement, surface angle, abrasion, UV ageing and how long water remains pooled.
Water-column testing
What hydrostatic head actually measures
In a hydrostatic-pressure test, a fabric specimen is clamped into a test head and exposed to steadily increasing water pressure. The reported value represents the pressure at which the specified leakage endpoint is reached. The result is commonly written as millimetres of water column, mm H₂O, or simply “mm.”
ISO 811 and AATCC TM127 are two commonly referenced methods for measuring resistance to water penetration under hydrostatic pressure. A serious procurement specification should name the method rather than listing only a number, because test equipment, pressure increase rate, specimen preparation and endpoint rules can influence the result.
Important: 10,000 mm does not mean a finished tarp should be used as the wall of a ten-metre-deep tank. It is a pressure-equivalent laboratory rating for a fabric specimen under defined conditions.
2,000 mm
≈ 19.6 kPa
8,000 mm
≈ 78.5 kPa
10,000 mm
≈ 98.1 kPa
2,000 vs 8,000 vs 10,000 mm
How to interpret each tarp waterproof rating
The table below is an application-selection guide, not a universal pass/fail rule. Final suitability should be confirmed using the same test method, representative production samples and the finished-product construction.
| Hydrostatic head | Pressure equivalent | Practical meaning | Typical procurement direction | What still needs checking |
|---|---|---|---|---|
| 2,000 mm2 m water column | ≈ 19.6 kPa ≈ 2.84 psi |
A meaningful waterproof benchmark for many coated tarp fabrics exposed mainly to rain, provided the coating is continuous and the finished cover drains correctly. | General truck covers, equipment covers, temporary weather protection, sloped canopies and standard outdoor PVC tarpaulin programs. | Welded or sealed seams, no long-term ponding, adequate UV package, correct tensioning and sufficient tear strength around fixings. |
| 8,000 mm8 m water column | ≈ 78.5 kPa ≈ 11.38 psi |
A much higher water-pressure margin for fabric that may experience contact pressure, repeated wet use or more demanding waterproof-product expectations. | Dry-bag material, higher-grade tent floors, marine covers, industrial enclosures, demanding storage covers and premium reusable tarp lines. | Flex-cracking after folding, abrasion resistance, coating adhesion, weld compatibility, low-temperature flexibility and ageing after UV exposure. |
| 10,000 mm10 m water column | ≈ 98.1 kPa ≈ 14.22 psi |
High hydrostatic resistance for buyers seeking a larger safety margin against penetration through the coated fabric. | High-spec waterproof covers, ground-contact barriers, containment-oriented fabric systems and applications where pressure or prolonged moisture exposure is a major concern. | Whether the complete product is designed for containment; seam and fitting tests; chemical compatibility; puncture risk; field installation and drainage strategy. |
Pressure conversions are rounded. Actual acceptance criteria should be written into the purchase specification together with the test method and sampling plan.
Beyond the headline number
Why two tarps with the same rating may perform differently
Hydrostatic head is valuable because it is measurable. It becomes misleading only when it is treated as the complete description of a tarp.
Coating structure
PVC coating weight, formula, pinhole control, base-fabric coverage and coating adhesion affect whether the rating remains stable after folding, welding and outdoor use.
Seams and fabrication
Needle holes, poorly set welding parameters, unsealed overlaps and fittings can become leakage paths even when the flat fabric has a high laboratory rating.
Ponding and geometry
A sloped, correctly tensioned tarp sheds water. A loose cover creates pockets where water accumulates, adding weight and sustained pressure at low points.
Abrasion and pressure points
Cargo corners, ground contact, kneeling, straps and repeated dragging can damage the coating locally. High tear and abrasion resistance often matter as much as the initial water-column value.
UV, temperature and ageing
Sunlight, plasticizer migration, cold flexing, heat and cleaning chemicals can change coating performance. Buyers should distinguish initial test data from aged-performance requirements.
Application matching
Which hydrostatic-head range should a buyer request?
Start with the real service condition, then determine the required pressure margin. Higher is not automatically better when it adds weight, stiffness or cost without solving the actual failure mode.
Truck and trailer covers
Rain exposure, wind, tension, abrasion and repeated handling dominate. Seam welding and tear strength are critical.
Common starting direction: 2,000 mm+Temporary roofs and site covers
Drainage slope, fastening, wind uplift and puncture risk may govern field performance more than an extreme rating.
Common starting direction: 2,000–8,000 mmTents and canopies
Flysheet and roof panels see falling rain, while floor panels experience body and ground pressure.
Typical direction: roof lower, floor higherDry bags and marine covers
Folding, welding, splash, repeated wet contact and pressure against contents require a more demanding fabric system.
Common starting direction: 8,000 mm+Ground contact and containment
Standing water, puncture, fittings and seam integrity require application-specific engineering and finished-product testing.
Direction: 10,000 mm or project-defined
DERFLEX manufacturing support
Specify the waterproof system—not just a marketing number
DERFLEX supplies PVC-coated polyester fabric for tarps, covers, shelters, dry bags, logistics, construction and industrial conversion. Depending on the project, a buyer can discuss 2,000 mm, 8,000 mm, 10,000 mm or another verified hydrostatic-pressure target together with the base cloth and finished-product requirements.
The objective is to create a repeatable production specification that balances water resistance with tensile strength, tear resistance, flexibility, weldability, abrasion performance, UV exposure and commercial processing.
- Custom GSM, thickness and roll width
- Polyester denier and weave selection
- PVC coating or lamination structure
- Matte, gloss or lacquered surface
- UV, flame-retardant and cold-flex options
- Hot-air and high-frequency welding support
- Roll goods or fabricated tarp discussion
- Sample and batch test documentation
Procurement checklist
What to put in a hydrostatic-head tarp specification
A complete inquiry reduces sample rounds and makes quotations easier to compare across manufacturers.
Test requirement
Name ISO 811, AATCC TM127 or the agreed customer method, including the acceptance value and whether the test applies to initial or aged material.
Material structure
Define PVC-coated or laminated polyester, base-fabric denier, yarn density, total GSM, thickness, coating side and surface treatment.
Mechanical data
Include tensile strength, tear strength, adhesion, abrasion and flex resistance where the tarp will be tensioned, folded or dragged.
Fabrication route
State whether panels will be hot-air welded, high-frequency welded, sewn and sealed, fitted with eyelets, reinforced with webbing or supplied as finished covers.
Environment
Describe UV exposure, temperature range, wind, chemicals, saltwater, cleaning method, ground contact, ponding risk and intended service duration.
Quality evidence
Request a representative sample, technical data sheet, test report and agreed lot-inspection plan. For critical projects, test the completed seam or finished assembly as well as the flat fabric.
Continue your tarp research
Related DERFLEX waterproof tarp resources
These six pages connect hydrostatic pressure with material selection, finished-cover construction and bulk PVC tarpaulin sourcing.
Frequently asked questions
Hydrostatic head for tarps FAQ
Clear answers for buyers comparing waterproof ratings and preparing a custom tarp inquiry.
Is a 2,000 mm hydrostatic head waterproof enough for a tarp?
It can be suitable for many rain-cover applications when the PVC coating is consistent, seams are correctly welded or sealed, the tarp is tensioned and water can drain. It may not be the right target for prolonged ponding, ground pressure, containment or heavily abraded surfaces.
What does an 8,000 mm waterproof rating mean?
It means the tested fabric resisted pressure equivalent to an eight-metre column of water before reaching the stated penetration endpoint. That is approximately 78.5 kPa or 11.38 psi. The test value applies to the specimen and method reported, not automatically to every seam and fitting in the finished product.
Is 10,000 mm always better than 2,000 mm for tarps?
Not automatically. A higher rating provides a larger water-pressure margin, but the best material must also meet weight, flexibility, weldability, tear, abrasion, UV, temperature and cost requirements. For a sloped truck cover, improving edge reinforcement may create more value than specifying an unnecessarily high hydrostatic head.
Which test standard should be used for tarp hydrostatic head?
ISO 811 and AATCC TM127 are commonly referenced hydrostatic-pressure methods for textiles. The purchase order should identify the agreed method, acceptance level, specimen condition and whether third-party or factory test evidence is required.
Can a high-rated tarp still leak?
Yes. Leakage may occur through stitched seams, damaged coatings, poorly welded joints, eyelet areas, punctures or water pockets even when the flat fabric has a high laboratory rating. Finished-product design and fabrication remain essential.
Can DERFLEX customize hydrostatic-head performance?
DERFLEX can discuss application-specific PVC tarpaulin structures, including coating construction, GSM, polyester reinforcement, width, finish, UV package, flame-retardant direction and hydrostatic-pressure targets. Final values should be confirmed through sample testing and an agreed production specification.
Need 2,000 mm, 8,000 mm, 10,000 mm—or a project-specific target?
Send DERFLEX your application, target test method, fabric weight, roll width, color, quantity, fabrication process and environmental requirements. The team can help organize a practical PVC tarpaulin specification and sample route for your program.
Hydrostatic-head recommendations on this page are application-selection guidance. Final product suitability should be verified against the agreed test method, samples, fabrication and field conditions.