Special Fixtures, Drains & Interceptors
Clothes washer drains, dishwasher connections, grease interceptors, floor drains, and fixture-specific requirements.
- State clothes washer standpipe and drain size requirements
- Describe dishwasher drain connection requirements including air gap or high loop
- Explain grease interceptor requirements for commercial food service
- Identify lead-free requirements under the Safe Drinking Water Act
Lección 1
Clothes Washer Standpipes & Dishwasher Connections
Clothes Washer Drain Requirements
A residential clothes washer requires a standpipe that serves as the open-air connection between the washer discharge hose and the building's DWV system. The standpipe requirements include:
- Minimum drain pipe size: 2 inches
- Standpipe height: 30 to 42 inches above the trap weir
- The standpipe must connect to a properly trapped and vented drain
- The washer discharge hose inserts into the top of the standpipe (not a sealed connection)
The standpipe height is critical. If too short, the washer's pump pressure can cause water to overflow. If too tall, the pump cannot lift water high enough and the washer will not drain properly.
Dishwasher Drain Connections
A dishwasher drain connection requires either an air gap or high loop to prevent backflow. This prevents contaminated water from the garbage disposal or sink drain from siphoning back into the dishwasher.
Air Gap (Preferred)
Physical separation device mounted at countertop level
Required in: Many jurisdictions (especially California)
Advantage: Most reliable backflow protection
High Loop
Drain hose looped to underside of countertop before connecting to disposal
Required in: Jurisdictions that accept alternative to air gap
Advantage: Simpler installation, no countertop penetration
Clothes washer standpipe details:
The standpipe is the visible section of pipe that extends above the floor and receives the washer discharge hose. Key requirements:
- The trap must be accessible (not concealed) for inspection and cleaning
- The standpipe must be vented through the vent system - it is not self-venting
- In laundry rooms, a floor drain must be provided if required by code to handle standpipe overflow
Commercial laundry requirements: Commercial laundries and laundromats produce larger wastewater volumes and may require lint traps or interceptors in addition to standard standpipes. Lint is a significant sewer maintenance problem from commercial laundries.
Dishwasher high loop height: When a high loop is used instead of an air gap, the drain hose must be looped to the highest point possible under the countertop - typically fastened directly to the underside of the countertop. The loop must be higher than the drain inlet of the garbage disposal. If the disposal inlet is at the same height as the drain connection, the high loop does not provide adequate protection.
Clothes washer standpipes require a 2-inch minimum drain and height of 30 to 42 inches above the trap weir. Dishwasher drains require an air gap or high loop to prevent backflow. The high loop must be fastened at the highest point possible under the countertop, above the garbage disposal inlet.