Water Penetration Testing at 15% DP

Florida's hurricanes bring walls of water. Watch how windows are tested with spray racks delivering 5 gallons per hour while pressure simulates wind-driven rain conditions.

ASTM E331 Water Test - Live Simulation
➡
➡
➡
PRESSURE
✓
DRY
INTERIOR
Collection Trough
Design Pressure
50
PSF
Test Pressure (15%)
7.5
PSF
Spray Rate
5
gal/hr/ft²
Interior Leakage
0
PASS
00:00
Test Duration (15:00 Required)

Why 15% of Design Pressure?

Water infiltration happens at lower pressures than structural loads during sustained rain events.

Design Pressure (DP-50) 50 PSF
100% - Structural Load
Water Test Pressure (15%) 7.5 PSF
15%
DP-40
40 x 0.15
6 PSF
Water Test
DP-50
50 x 0.15
7.5 PSF
Water Test
DP-65
65 x 0.15
9.75 PSF
Water Test
DP-80
80 x 0.15
12 PSF
Water Test

The ASTM E331 Test Process

Step-by-step water penetration resistance testing.

Mount Test Specimen

Window or door is installed in test chamber exactly as it would be in the field, including all weatherstripping and hardware.

Field-representative installation
1

Activate Spray System

Water spray racks deliver 5 gallons per hour per square foot uniformly across the exterior surface.

5 gal/hr/ft²
2

Apply Test Pressure

Positive air pressure at 15% of design pressure is applied to simulate wind-driven rain conditions.

15% of DP
3

15-Minute Duration

Test runs for full 15 minutes. Any water appearing on interior side at any time constitutes failure.

Zero water tolerance
4

Frequently Asked Questions

Common questions about water penetration testing.

Why is water testing done at 15% of design pressure?
+
15% of design pressure simulates typical wind-driven rain conditions. While hurricanes can produce higher pressures momentarily, sustained rain penetration typically occurs at lower pressures. A DP-50 window is water tested at 7.5 PSF (50 x 0.15 = 7.5).
What is ASTM E331 water penetration testing?
+
ASTM E331 is the standard test for water penetration resistance. Water is sprayed at 5 gallons per hour per square foot onto the exterior while positive pressure is applied. The test runs for 15 minutes with zero water allowed on the interior side.
How much water is used in water penetration testing?
+
The standard spray rate is 5 gallons per hour per square foot of test area. This simulates heavy wind-driven rain conditions during a tropical storm or hurricane, ensuring the product can resist water infiltration under sustained exposure.
What happens if a window fails water testing?
+
Any water appearing on the interior side during the 15-minute test constitutes failure. The product cannot be certified until the manufacturer identifies and corrects the leak source - typically weatherstripping, corner joints, or weep system design.

Calculate Your Water Test Requirements

Know the exact water test pressure your products must meet based on your wind load calculation.

Calculate Wind Loads View Pricing