How to Repair Silcock when Leaks from Cap on Top

Instructions on Repairing a Leaking Outdoor Spigot When the Vacuum Breaker Fails

By Mark J. Donovan

Question: Mark, I have an outdoor spigot that is leaking from the cap on top of it. Can you explain how do I repair a Silcock when it leaks from the cap on top?

Answer: Elise, It is the vacuum breaker that has probably failed/worn out on the Silcock, or more specifically the vacuum breaker float assembly. It is a tiny rubber disk underneath the plastic cap that is forced up each time the outdoor spigot is turned on, and is supposed to fall down when the valve is turned off. With most silcocks you can relatively easy replace the rubber disk inside the Vacuum Breaker.

First turn off the Silcock and pry off the vacuum breaker cap. Then slightly tighten the plastic nut with a pair of adjustable pliers. Then turn on the Silcock and see if the leak has stopped.

If the leak persists, then turn off the silcock again, as well as the water to the outdoor spigot from inside the house.

Next, pry the vacuum breaker cap off of the spigot with a common screw driver.

Then remove the breaker retaining nut with a pair of adjustable pliers.

Now remove the vacuum breaker float assembly with your fingers.

Examine it and clean off any gunk or debris that is on it with a rag and rinse it off with water. Mineral deposits on the assembly may be causing the valve/washer assembly not to seat well. So if you see any hard mineral deposits on the valve carefully scrape it off with the common screw driver.

Reinstall the vacuum breaker float assembly and reattach the retaining nut. Then snap the cap back on and turn on water to the spigot and then turn on the silcock to see if the leaking has stopped.

How to Repair a Silcock when it Leaks from the Cap on Top

If not, remove the vacuum breaker assembly again and go to a home improvement center and find a replacement part. Make sure to bring the vacuum breaker and retaining nut with you to compare with the replacement part.

Then install the new vacuum breaker replacement part onto the silcock and try it again. With any luck the silcock vacuum breaker leak will be just a memory.

For information on installing a shower pan membrane liner for a ceramic tile shower, see the Shower Pan Membrane Liner Installation eBook from  The Shower Pan Membrane Liner EBook will quickly teach you the step-by-step process for installing the shower pan membrane liner correctly. It includes instructions on framing the shower stall, pouring the pre-slope and shower base mortar, and installing the shower pan membrane liner.

For information on how to tile a custom ceramic tile shower, see the “How to Tile a Custom Ceramic Tile Shower eBook” from This eBook will quickly provide you with step-by-step instructions on how to measure and install ceramic tile in a shower, including the installation of tile on shower walls, floors and curbs. It provides detailed instructions for every step in the process of tiling a custom ceramic tile shower and is loaded with instructional pictures!

Related Information

Additional Plumbing Resources from

Get Free Bathroom Remodeling Price Quotes with No Obligation!

Fill out our 3-5 minute quick and easy form, and receive a free price quote on a bathroom remodeling project from one of our pre-screened and licensed bathroom remodeling contractors. This process is free and there is no obligation to continue once you receive your bathroom addition price estimate.