Answering the common question about drainage safety for water softener systems, these air gap kits prevent backflow by creating a dedicated air gap between the discharge line and the standpipe. They are best for homeowners installing or upgrading water softeners, especially where standpipes are 1-1/2 inches or 2 inches in diameter. This guide highlights five top options, detailing who they are best for, and why they stand out. A quick buying table follows to help compare at a glance.
| Product | Best For | Why It Stands Out |
|---|---|---|
| Water Softener Air Gap with 1/2-inch Barb Connector (ET117-008) | Installers needing a 1/2″ barb inlet and 1-1/2″ standpipe | Simple installation, wide compatibility with PVC adapters, splash-free operation |
| Water Filter/Softener Air Gap With 1/2-inch Inlet (ET115-001) | 1-1/2″ or 2″ standpipes, flexible with adapters | 0.5–7 GPM range, broad standpipe compatibility |
| Dual Air Gap for Water Softener and RO (AG130-001) | Systems requiring dual-service air gap (RO + softener) | Multiple inlet sizes (including 5/8″ and 3/8″), splash protection |
| PP855-69 2 in. Water Softener Air Gap | Standard 1-1/2″ or 2″ standpipes, shared usage | Backflow protection, easy 3-level mounting |
| Water Softener Air Gap (ET115-002) | 3/4″ inlet option, 1-1/2″ or 2″ standpipes | 0.5–9 GPM range, flexible installation |
Water Softener Air Gap with 1/2-inch Barb Connector
Brand: AIR GAP INTERNATIONAL
- Simple installation: 1/2-inch barb inlet for 1/2″ ID tubing; 1-1/2″ OD outlet to standpipe; includes PVC adapters; pressure fit or glued to plastic standpipes.
- Standpipe connection: Outlets compatible with various materials; flow capacity up to 15 GPM.
- Dry operation: Splash guard ensures a completely dry exterior operation.
Best for: Homeowners installing a single softener drain with a straightforward, reliable connection. Choose this if you want a compact, easy-to-install solution with standard adapters. Caution: Ensure your standpipe and adapters match the included fittings for a secure seal.
Water Filter/Softener Air Gap With 1/2-inch Inlet (ET115-001)
Brand: EcoTech
- Flow rate: 0.5–7 GPM; air gap remains dry at ends of range, reducing splash risk.
- Simple installation: 1/2″ MIPT inlet; compatible with 1-1/2″ or 2″ standpipes via adapters; pressure fit or glue.
- Standpipe compatibility: Connects to 1-1/2″ or 2″ standpipes with couplers; 15 GPM max capacity.
Best for: Systems using 1-1/2″ or 2″ standpipes with a desire for broad adapter compatibility and a proven dry-out design. Caution: Flow rate varies with standpipe size and fittings; verify proper clearance for your installation.
Dual Air Gap for Water Softener and RO (AG130-001)
Brand: AIR GAP INTERNATIONAL
- Easy to connect: 1/2″ OD inlet supports 1/2″ PVC and 5/8″ tubing; RO port provides 3/8″ or 1/4″ options.
- Standpipe compatibility: Fits 1-1/2″ and 2″ standpipes; includes splash protection; maximum recommended flow is 4–5 GPM.
- Uses: Suitable for homes with both water softener and RO systems sharing a standpipe.
Best for: Households with both a water softener and an RO system needing a single standpipe drainage solution. Caution: The RO port requires compatible tubing adapters; ensure compatibility before purchase.
PP855-69 2 in. Water Softener Air Gap
Brand: RPBKE
- Standpipe compatibility: Works with 1-1/2″ and 2″ standpipes; allows three level mounting options.
- Backflow protection: Provides essential anti-siphon protection for water supply.
- Design: Standard air gap for soft rubber hoses or aluminum washer drains; recommended flow 1–7 GPM.
Best for: Homes upgrading to a versatile air gap that supports multiple mounting heights and shared standpipes. Caution: Check mounting levels in tight spaces to ensure clear piping routes.
Water Filter/Softener Air Gap With 3/4-inch Inlet (ET115-002)
Brand: AIR GAP INTERNATIONAL
- Flow: 0.5–9 GPM; dry exterior at min/max flow rates to avoid splash.
- Installation: 3/4″ MIPT inlet; works with 1-1/2″ or 2″ standpipes via couplers; pressure fit or glue.
- Standpipe: 15 GPM capacity; designed for flexible connection with common drain lines.
Best for: Installers needing a 3/4″ inlet option with broad standpipe compatibility. Caution: Inlet size differs from other ET models; confirm piping before ordering.
Water Softener Air Gap for Washing Machine Box (AG140-001)
Brand: AIR GAP INTERNATIONAL
- Designed for recessed washing machine boxes with 2″ drainpipe; 1/2″ OD inlet fits 1/2″ PVC slip fittings.
- Standpipe base: 2″ PVC mounting base included; splash guards provide a dry operation window.
- Flow: Tested at 15 GPM; recommended usage around 7 GPM for optimal performance.
Best for: Homes with a dedicated washing machine outlet box that also handles softener discharge. Caution: Requires a recessed box compatible with the 2″ drainpipe setup.
2 in Water Softener Air Gap for 1-1/2″ or 2″ Standpipes
Brand: HWEIUA
- Versatile standpipe fit: Works with 1-1/2″ and 2″ standpipes; three height positions for installation flexibility.
- Standard design: Supports soft rubber washer hoses and aluminum washer drains; 1–7 GPM recommended.
- Durable construction: Corrosion-resistant plastic; enables multiple units on a single drain line when needed.
Best for: Houses needing a highly adjustable air gap that can share a standpipe with other units. Caution: Ensure adequate space for multiple air gaps on the same drain connection.
Plumb Pak PP855-69 2 in. Air Gap
Brand: Plumb Pak
- Backflow protection: Full anti-siphon protection for wastewater safety.
- Easy to install: Fits 1-1/2″ and 2″ standpipes; three mounting levels support different configurations.
- Standard design: Works with soft rubber hoses or aluminum washer drains; 1–7 GPM range recommended.
Best for: Those who want a proven, widely compatible air gap with straightforward installation. Caution: Verify standpipe compatibility with your existing drain hardware.
Buying Guide: Key Purchase Considerations
- Standpipe size compatibility: Most units fit 1-1/2″ or 2″ pipes. Confirm your standpipe diameter before purchasing.
- Inlet connection size: Inlets range from 1/2″ to 3/4″ to accommodate different discharge hoses. Match your tubing size to the inlet.
- Flow rate: Typical recommendations span 1–7 GPM, with some models up to 9 GPM. Choose based on your system’s discharge rate to avoid splashing or dry-out conditions.
- Mounting and placement: Some air gaps provide multiple mounting heights or can share a standpipe with other devices. Consider your cabinet or box space and accessibility for maintenance.
- Splash protection: Splash guards reduce water near the air gap exterior. Look for models advertising splash protection for a cleaner installation.
- Adapters and versatility: Models with adapters for PVC, threaded PEX, or multiple standpipe materials offer greater installation flexibility.
Frequently Asked Questions
- What is an air gap for a water softener, and why do I need one? Answers: An air gap creates a physical separation between the discharge line and the drain to prevent backflow into the potable supply, protecting water quality.
- What standpipe sizes do these kits support? Answers: Most kits support 1-1/2″ and 2″ standpipes, with some models offering alternative inlet sizes and adjustable mounting.
- Can I install an air gap with a washing machine box? Answers: Yes, certain models are designed for recessed washing machine boxes with compatible drainpipes.
- Do these air gaps affect water pressure or filtration performance? Answers: Air gaps are drainage devices and do not treat water or affect filtration; they only safeguard drainage.
- How do I choose between a single air gap and a dual air gap kit? Answers: Choose dual if you need separate discharges for RO and softener, or if you want one shared standpipe with independent discharge control.