Anti-Siphon Valve Leaking Outdoors? (We Have A Fix)

Ossiana Tepfenhart
by Ossiana Tepfenhart

When you’re working on your landscaping, the water that you’re using will be flowing from a small spigot known as an anti-siphon valve. These can be found on sprinklers as well as on the sides of your home. The anti-siphon action helps prevent water from leaking out and keeps outdoor water from contaminating your home’s water supply. But, what happens when this thing starts to leak?

Make sure to check that you properly closed the valve before you panic. If you have an anti-siphon valve that’s leaking, there are only two ways that you can solve the problem. You can either choose to clear any dust inside of it out (if yours has the mechanism to do so), or you can replace the valve. In most cases, replacement is the best option.

A leaky anti-siphon valve, or ASV, is something that seems like it’s a minor problem, but it’s really indicative of something worse. For the sake of your water bills and your sanity, use this guide to help you out.

Do You Need to Hire a Plumber?

Get free, zero-commitment quotes from pro contractors near you.

Why Is My Anti-Siphon Valve Leaking?

After a couple of years, it’s possible that you will start to notice that your anti-siphon valve won’t be working the way that it used to. This is because ASVs are prone to wear and tear, which can often cause leaks. You can also have a leak because of trapped dirt and grime. If you can clear out the grime, you may be able to fix your ASV without replacing it.

For the most part, anti-siphon valves leak as a result of wear and tear. The inner workings start to fail after 10 to 20 years, especially when it comes to rubber seals and similar matters. While not all ASV leaks can be prevented, having a high-quality valve can delay the inevitability of faucet failure.

How To Fix Your Leaky Anti-Siphon Valve

A leaky anti-siphon valve can be fixed in two main ways, one of which depends on whether or not you have a frost-free anti-siphon valve. Let’s talk about how you can fix either issue…

Cleaning Out The Valve

In many cases, there is an easy fix that can make your valve act good as new. It’s so easy, it’s actually considered to be part of regular house maintenance! The simple trick is called giving your valve a quick and easy cleanout. If you have a frost-proof anti-siphon valve that’s on the side of the building, then you can try to work out the grime by doing this:

  • Take a look at your valve, and locate the plastic cap near the top of the spigot. Remove the cap, exposing the valve mechanism.
  • Grab a pair of adjustable pliers and remove the valve bonnet. Unscrew it, don’t try to pull it out unless it’s already loose.
  • The poppet will fall out of your valve’s bonnet. This is the part that you will need to clean.
  • Wipe it down and remove the dirt if you need to. If you notice that it’s cracked, you can also go to the hardware store and get a replacement poppet to place in there instead.
  • Turn on the water to flush out any additional dirt in your system. Don’t worry, you do not have to shut off water flow to do this.
  • Put the poppet back in the valve. Screw it in, and check to see if the leak is still there. If it’s fixed, replace the plastic cap and you’re done.

Replacing Your Entire Anti-Siphon Valve

Sometimes, the anti-siphon valve will have problems that can’t be fixed by a simple cleanout or poppet switch. When this happens, replacement is the only way to make it work. Most outdoor faucets have a screw-on function, especially if they are not on a sprinkler system. Here’s what you will need to do in order to fix this:

  • Run to Home Depot (or any other hardware store) and get a new anti-siphon valve. You will need to get one of the types that is able to be screwed in. If you have a sprinkler system, get a valve that matches your current system. A store associate can help.
  • Remove the setting screws from the valve. A small screwdriver (not a Philips head) will usually work out well here. Pull off the anti-siphon valve once the screws are loose. If your valve is on a sprinkler system, you may need to saw off the PVC pipe portion that contains the old valve. Should this be the case, it’s best to consult a handyman or a sprinkler repairman instead.
  • If your screws are rusted on, then use a lot of WD-40. You want to avoid de-threading the screws, since this will make it a lot harder to fix. Let the WD-40 sit on the screws, try to wipe away any corrosion you see, and gently remove the screws.
  • Pull the anti-siphon valve off, then replace it with the new valve. It should slide into place.
  • Add the screws back in, securing it gently. You want to make sure that the valve is tightly affixed in place. If you are replacing a sprinkler head, let a handyman do it instead. If you want to do it on your own, add new PVC piping and affix your new sprinkler head to a new pipe.

How Bad Is A Leaking Anti-Siphon Valve?

It depends on what you want to define as “bad.” If you are worried about being able to use your water outside, then don’t be. A leaky anti-siphon bad won’t prevent you from being able to turn on the water nor will it lead to a contaminated water system in most cases. However, that doesn’t make it alright.

Leaky faucets are more of a problem when it comes to your water bills, since you’re basically wasting water. If you live in a cold area where freezes happen a lot, then you also might be contributing to long-term damage to the system your valve is attached to. As a result, you need to make sure to fix the problem as soon as you can.

Is This A Good DIY Project?

Assuming that you don’t have to do too much finagling with PVC piping, it’s safe to say that it would be silly to hire a handyman for this. This is a project that should literally take under 20 minutes to do in most cases. Of course, if you are not comfortable with a saw or you have a really complex sprinkler system, you might want to talk to a professional instead.

How Much Does A Replacement Anti-Siphon Valve Cost?

While ASVs are considered to be a basic part of your home’s setup, they are not “basic” when it comes to pricing. A typical anti-siphon valve will cost anywhere between $100 to $300 for a full kit. Despite the high price tag, you should not assume that it’s the highest-priced valve you can get. Some types of faucets can cost over $1000.

If you want to get the valve professionally replaced, you will have to pay for labor too. The labor will be between $50 to $100 more, depending on where you live and how badly rusted the parts are.

Do You Need to Hire a Plumber?

Get free, zero-commitment quotes from pro contractors near you.

Related Questions

Are anti-siphon valves necessary?

Absolutely. Building codes require that the outdoor faucets attached to homes have some form of protection from siphoning action. Without an ASV, there is a good chance that unclean water from the outside will leech into your home’s water system, contaminating it.Since the water inside your home also gets connected to municipal water supplies, contamination in your home can cause serious problems for everyone around you. To prevent contamination of the water supply, homeowners are expected to have and maintain their anti-siphon valves. Not doing so can prevent your home from being up to code.

Where is the best place to install an anti-siphon valve?

If you just bought an anti-siphon valve, there are two places that you can install it. You can install it where water comes out of your home for a hose, or you can use it as a part of a sprinkler system. ASVs need to be installed above ground at a higher point than all other valves and spigots in a sprinkler system.Most people choose to add an anti-siphon valve six to 12 inches above ground level. This ensures that they can do the work they’re supposed to do without issue.

What does an anti-siphon valve do?

An anti-siphon valve is there to normalize and balance out the water pressure in your system. By balancing out the pressure, your system has a way to avoid getting water flowing back into your system if it hasn’t been expressed through the spigot. This prevents your water system from getting contaminated by things like dirt or pesticides.The best way to explain it is that you’re using the ASV to keep your water supply and your town’s water a little cleaner.

Ossiana Tepfenhart
Ossiana Tepfenhart

Ossiana Tepfenhart is an expert writer, focusing on interior design and general home tips. Writing is her life, and it's what she does best. Her interests include art and real estate investments.

More by Ossiana Tepfenhart