6 Best Anti Siphon Sillcocks For Preventing Backflow For Total Peace of Mind
Anti-siphon sillcocks are crucial for preventing backflow contamination. This guide reviews the top models to help safeguard your home’s water supply.
You leave a hose in the water trough overnight, or maybe in a bucket of fertilizer mix you were preparing for the garden. The next morning, a water main breaks down the road, causing a sudden drop in pressure in your house lines. That contaminated water from the trough or bucket can get sucked backward into your home’s plumbing, poisoning the water you and your family drink. This isn’t a scare tactic; it’s a real risk called back-siphonage, and it’s why the simple outdoor spigot, or sillcock, is one of the most critical safety devices on your property.
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Why Anti-Siphon Sillcocks Protect Your Water
Backflow is any unwanted reversal of water flow. On a farm, the opportunities for it are everywhere. Hoses are left in stock tanks, chemical sprayers, or muddy puddles. When pressure in your main supply line drops lower than the pressure at the end of the hose, a vacuum is created, and whatever that hose is sitting in gets siphoned right back into your pipes.
An anti-siphon sillcock prevents this with a simple, brilliant device: a vacuum breaker. This one-way air valve sits on top of the sillcock. If it senses negative pressure (a siphon), it opens to let air in, which breaks the vacuum and stops the backflow in its tracks. It physically separates the potentially contaminated water in your hose from the clean water in your house.
This isn’t just a building code requirement; it’s fundamental water safety. Standard spigots without this protection are a liability waiting to happen. Upgrading to an anti-siphon model is one of the cheapest and most effective ways to ensure the water coming out of your kitchen tap is safe to drink, no matter what’s happening at the other end of your hose.
Woodford Model 19: The Ultimate Frost-Proof Pick
When you want to install something once and forget about it, you get a Woodford. The Model 19 is the benchmark for frost-proof sillcocks for a reason. It’s built like a tank, operates smoothly, and is designed specifically to survive harsh winters, which is non-negotiable in most climates.
Its key feature is the patented Pressure Relief Valve (PRV). This small valve automatically drains water from the sillcock’s internal chamber, even if you foolishly leave a hose attached during a freeze. Other frost-proof models can still rupture if trapped water freezes and expands. The Woodford vents this pressure, saving you from a burst pipe inside your wall.
Yes, it costs more than the others. But a single frozen pipe repair, with the associated water damage and drywall work, will cost many times more. Think of the Woodford 19 not as an expense, but as cheap insurance against a winter catastrophe. For a critical, high-use spigot on the house or barn, it’s the smart investment.
Prier P-164: Heavy-Duty Choice for High-Use Areas
The Prier P-164 is a true workhorse. It’s a heavy-duty, no-nonsense sillcock that feels solid in your hand and is built to withstand the daily abuse of a busy property. If you have a spigot in a high-traffic area where it might get bumped by a wheelbarrow or kicked by a boot, this is the one you want.
Its all-brass and heavy-duty aluminum construction inspires confidence. The design is simple and proven, with readily available parts for the day it eventually needs a new washer. That serviceability is a huge plus; you can rebuild it in minutes without having to rip it out of the wall. It’s a product made for people who fix their own equipment.
While it lacks the fancy pressure-relief feature of the Woodford, its robust build and reliable frost-proof design make it an excellent choice for most applications. It provides fantastic protection and durability at a more moderate price point, making it a go-to for outfitting a barn or workshop where function and toughness are the top priorities.
SharkBite 24628LF: Easiest DIY Installation
Let’s be honest: not everyone is comfortable sweating copper pipes with a torch. The SharkBite sillcock completely eliminates that barrier to entry. Its genius is the push-to-connect fitting on the end. You just clean your pipe, mark the depth, and push the sillcock on. That’s it.
Some old-timers are skeptical of push-fittings, but the technology is proven, code-approved, and incredibly reliable when installed correctly. For a hobby farmer with a long list of weekend projects, the time saved is immense. You can replace a faulty sillcock in 15 minutes without any special tools, which means you’re more likely to actually do it.
This model isn’t just about the connection, either. It’s a quality, frost-proof, anti-siphon sillcock that does its job well. The primary reason to choose it is convenience. If you value your time and want to tackle plumbing repairs yourself with minimal fuss and maximum confidence, the SharkBite is an outstanding solution.
Mueller Proline Quarter-Turn for Simple Operation
Sometimes, the best features are the simplest ones. The Mueller Proline stands out for its quarter-turn ball valve operation. Instead of twisting a handle multiple times to turn the water on or off, you just give it a quick 90-degree turn. This is a bigger deal than it sounds.
When your hands are cold, wet, or full of mud, fumbling with a traditional multi-turn handle is frustrating. A quick flick of the wrist is all it takes to get water flowing or shut it off completely. The lever also provides a clear visual indicator: if it’s parallel to the pipe, it’s on; perpendicular, it’s off. No more guessing.
This sillcock combines that modern convenience with a solid, frost-proof, anti-siphon design. It’s a great all-around performer that prioritizes ease of use. For anyone who uses their outdoor spigots frequently throughout the day, the quarter-turn action is a significant quality-of-life improvement.
Everflow 812-H: A Reliable and Affordable Choice
You don’t always need the top-of-the-line model for every single application. The Everflow 812-H is a perfect example of a budget-friendly sillcock that does the job without any frills. It’s a code-compliant, frost-proof, anti-siphon valve that provides the essential protection you need at a very attractive price.
This is the ideal choice when you need to install multiple spigots—say, around a new barn or garden area—and need to keep costs in check. While it may not have the overbuilt feel of a Prier or the advanced features of a Woodford, it is a perfectly capable and safe option. It meets all the necessary standards for backflow prevention and freeze protection.
Don’t mistake "affordable" for "cheap." The Everflow is a solid piece of hardware that will serve you well. It’s the practical, pragmatic choice for situations where you need reliable, basic function without paying for features you don’t need.
Legend Valve T-550: Durable Multi-Turn Design
There’s a reason the traditional multi-turn design has been around forever: it works, and it’s incredibly durable. The Legend Valve T-550 embodies this classic approach. It’s made from heavy-duty forged brass and is designed for fine control over water flow, which can be useful when filling smaller containers or using certain types of sprinklers.
Some people simply prefer the feel and precision of a multi-turn handle over a quarter-turn ball valve. The T-550 delivers that traditional operation in a robust, frost-proof, and anti-siphon package. Its heavy construction means it can handle the rigors of farm life, and its simple, time-tested mechanism is easy to service with basic parts.
This sillcock is for the person who values classic, overbuilt design and precise flow control. It’s a testament to the idea that you don’t need to reinvent the wheel to have a reliable, long-lasting product. If you appreciate traditional, heavy-duty hardware, the Legend T-550 is an excellent choice.
Choosing the Right Sillcock Length and Connection
Picking the right model is only half the battle; you also have to get the right size. The length of a frost-proof sillcock is critical. The measurement refers to the length of the stem that goes through your wall. The goal is for the actual valve seat—the part that shuts off the water—to be located well inside the heated envelope of your house, safe from freezing.
To find the right length, measure the thickness of your wall from the exterior siding surface to the interior wall surface. This includes siding, sheathing, the stud cavity, and drywall. Then, add an inch or two to be safe. Common lengths range from 4 inches to 12 inches or more, in 2-inch increments. Getting one that’s too short completely defeats the purpose of it being frost-proof.
You also need to match the connection type to your plumbing. The three main types are:
- Solder/Sweat: Requires a torch and experience to solder it onto a copper pipe. It’s a permanent, reliable connection.
- Threaded (MIP/NPT): Features male threads that screw into a female-threaded fitting. Requires pipe dope or Teflon tape to seal.
- Push-to-Connect: The easiest for DIY. Simply pushes onto copper, PEX, or CPVC pipe for an instant, watertight seal.
Choose the connection that matches your existing plumbing and your comfort level with the installation. When in doubt, a push-to-connect model like the SharkBite is the most forgiving for a non-plumber.
Ultimately, the best anti-siphon sillcock isn’t a single brand, but the one that fits your climate, your budget, and your specific needs. Whether you prioritize the bomb-proof reliability of a Woodford, the DIY-friendliness of a SharkBite, or the simple utility of an Everflow, the most important decision is to make the upgrade. Protecting your family’s water supply from backflow isn’t just a good idea—it’s your responsibility.
