The water softener air gap market offers a variety of backflow protection devices designed to prevent wastewater from contaminating your water supply. This guide highlights five top choices, outlining compatibility, installation ease, flow capacity, and splash protection. Each option is suitable for common home setups involving water softeners, reverse osmosis systems, and washing machine boxes. Use the buying guide below to compare features and select the best match for your plumbing configuration and local codes.
Summary Table of Selected Products
| Product | Brand | Inlet Type | Standpipe Fit | Notable Feature |
|---|---|---|---|---|
| Dual Air Gap Gap-Cap AG130-001 | AIR GAP INTERNATIONAL | 1/2 in OD, 5/8 in OD, 3/8 in RO port | 1-1/2 in or 2 in | Splash guards for dry operation; versatile inlet sizing |
| Plumb Pak PP855-69 | Plumb Pak | 1-1/2 in and 2 in | Metal or plastic standpipes | Full backflow protection; multi-level mounting |
| ET117-008 Water Softener Air Gap | AIR GAP INTERNATIONAL | 1/2 in barb | 1-1/2 in standpipe | 15 GPM flow; splash guard for dry operation |
| ET115-002 Water Filter/Softener Air Gap | AIR GAP INTERNATIONAL | 3/4 in MIPT threaded | 1-1/2 in or 2 in standpipes | 0.5–9 GPM range; 15 GPM max at standpipe |
| AG100-002 Universal Dual Air Gap | AIR GAP INTERNATIONAL | Two 3/8 in OD ports | 1-1/2 in or 2 in | Two independent inlets; up to 8 GPM per port |
Dual Air Gap Gap-Cap AG130-001
The Gap-Cap AG130-001 air gap is designed for flexible installation with 1/2-inch, 5/8-inch, and 3/8-inch inlets, accommodating various piping configurations. It fits both 1-1/2-inch and 2-inch standpipes and supports plastic or metal stands. The device includes a splash guard and a flow outlet capable of passing up to 7 GPM, with an optimum range around 4–5 GPM for dryer operation. Aimed at home water softeners and RO systems, the AG130-001 emphasizes secure placement and compatibility with common drain setups.
Key features include easy connection for PVC, PEX, and poly tubing, a 3/8-inch RO inlet, and compatibility with standard standpipes. Users should ensure the P-trap is located at least 20 inches from the top of the standpipe to prevent backflow and splashing. Installation flexibility makes this a versatile choice for retrofits or new builds.
Plumb Pak PP855-69 2 in. Plastic Water Softener Air Gap
The PP855-69 air gap provides full backflow and anti-siphon protection, making it suitable for preventing contaminants from entering the water supply. It is designed to fit both 1-1/2-inch and 2-inch standpipes, with flexible mounting at three different levels. The standard design accommodates soft rubber washer hoses or aluminum washer drain hookups that can share a standpipe with other air gaps. Typical flow guidance places usage from 1 to 7 GPM, translating to about 3.7 to 26.5 liters per minute. The unit emphasizes straightforward installation and compatibility with common standpipe configurations.
Installation considerations include ensuring compatibility with your standpipe material and confirming adequate clearance for multiple devices on the same standpipe. While not specific to RO systems, the PP855-69 provides robust backflow protection for a variety of drainage scenarios, including water softeners and laundry connections where venting and drainage reliability are essential.
Water Softener Air Gap With 1/2-Inch Barb Connector
The ET117-008 model is designed for connecting discharge tubing from a water softener to a drain line. It uses a 1/2-inch barb inlet and a 1-1/2-inch OD outlet that connects to a standpipe. Included PVC adapters enable secure connections to standpipes, and a black vinyl end cap is available as an accessory. The air gap supports a flow capacity of up to 15 GPM, with splash guards ensuring a dry exterior during operation. It is suitable for plastic or metal standpipes and can be pressure-fit or glued as needed.
Water Filter/Softener Air Gap ET115-002
The ET115-002 offers a 3/4-inch threaded inlet and connects to a 1-1/2-inch or 2-inch standpipe with couplers. It supports a broad flow range from 0.5 to 9 GPM, with a maximum recommended flow at 15 GPM through the standpipe setup. The unit is designed for easy installation with 3/4-inch threaded PVC pipe or compatible adapters from the ET170-XXX series. It is compatible with both 1-1/2-inch and 2-inch standpipes and can be pressure-fit or glued to a plastic standpipe. A versatile option for combined filtration and softening systems, it emphasizes reliable drainage and splash-free operation.
Water Softener Air Gap for Washing Machine Box AG140-001
The AG140-001 air gap is designed to install in a recessed washing machine outlet box with a 2-inch drainpipe. It features a 1/2-inch OD inlet to fit standard 1/2-inch schedule 40 PVC connections and provides space for a washer drain hose or soft rubber hose. The unit includes a 2-inch PVC mounting base for secure placement in the box. Splash guards support a dry exterior during discharge, and the system is tested at 15 GPM with a recommended 7 GPM duty cycle. It is a practical choice for laundry room installations where a compact, integrated air gap is desirable.
SafetyGaps.com DC-225-400 White
SafetyGaps DC-225-400 White offers adjustable height for floor drain covers with 3/8″, 1/2″, and 5/8″ hose ports. The device is mounted on the top surface of a vented floor drain receptor cover, with screws included for secure installation. Height can be adjusted up to 4 inches to stabilize the critical line above the Flood Level Rim, ensuring reliable drainage. This model is suitable for installations requiring precise positioning relative to the flood level and provides options for reverse osmosis discharge lines with the molded hose barbs. It emphasizes ease of installation and vertical adaptability.
SafetyGaps.com DC-225-400 Black
The black variant of the SafetyGaps DC-225-400 shares the same features as the white version, including adjustable height up to 4 inches, easy hose installation for 3/8″, 1/2″, and 5/8″ hoses, and a design that accommodates a reverse osmosis discharge line. This option provides aesthetic flexibility for installations where color matching to surrounding surfaces is preferred, while maintaining the same functional versatility for floor drain applications and air gap protection.
Universal Dual Air Gap AG100-002
The AG100-002 features two independent 3/8-inch OD input ports for simultaneous drainage. It includes sturdy standpipe compatibility for 1-1/2-inch or 2-inch pipes and passes up to 8 GPM per port, with the recommended flow around 5 GPM. This dual-inlet design supports redundancy and higher total flow for systems that require multiple discharge lines, such as combined water filtration and softening installations. The unit is designed to minimize tubing movement and is suitable for plastic or metal standpipes, with optional glue for plastic piping.
Buying Guide
Key considerations when selecting a water softener air gap include compatibility with your existing standpipe size (1-1/2 in or 2 in), inlet port sizing (1/2 in, 3/4 in, or 3/8 in for RO connections), and maximum flow capacity to prevent splashing or backflow during peak discharge. Splash guards and dry-operation features improve reliability and reduce splash risk, especially in busy laundry or utility areas.
Installation compatibility matters: determine whether the unit is pressure-fit or glue-to-plastic standpipes, and check if the device supports mounting in a recessed box, floor drain receptor, or direct standpipe connection. For homes with limited space or specific drainage setups, dual inlet models can offer flexibility and reduce installation complexity.
Material and finish can influence longevity and aesthetics. If the installation is exposed, choosing a model with a clean, low-profile design or color options may be beneficial. Finally, local plumbing codes often dictate the required backflow protection method, so verify that the chosen air gap complies with regional requirements and any RO discharge guidelines.