What Do Those Creepy Noises Behind the Walls Mean?

Plumbing Issues That Sound Like a Horror Movie

October is here, which means the spooky season is underway. And there are plenty of things that make autumn nights spooky - the howling wind, the rustling leaves, the bare tree branches scratching at the windows. Unnerving as these sounds can be, they're all part of fall's normal soundtrack. But when the creepy sounds are coming from inside the house, it's hard not to get a little freaked out - especially if no one knows what's causing them. 

Fortunately, the likely culprit isn't a monster, villain, or vengeful spirit, but simply a plumbing system that needs attention. So to clear up the mystery, this article will get to the bottom of three spine-tingling plumbing sounds homeowners often encounter - humming, whistling, and banging.

Haunted By Humming

One sound that can drive anyone batty is a persistent humming coming from the walls or fixtures. In some cases, this could be caused by a worn valve or washer in a faucet, showerhead, or other fixture. Toilets sometimes produce a humming sound if they have a worn fill valve or flapper.

However, humming sounds are more often a result of excessive water pressure. If the home's water pressure is too high, it can cause the supply pipes to vibrate, producing a steady hum within the walls. Homeowners can measure their home's water pressure with a pressure gauge from their local hardware store. Normal residential water pressure is around 40 to 60 PSI, so a professional plumber will need to adjust the pressure or install a water pressure regulator if it's higher than that.

Worrisome Whistling

Whistling or squealing noises coming from the walls can be truly blood-curdling. Like humming, whistling is often caused by high water pressure - more specifically, over-pressurized water being forced through a narrow passage, like where a larger supply pipe connects to a smaller one. Again, resolving a pressure issue like this will likely require the help of a professional.

Supply pipes may also whistle if they have a buildup of mineral scale inside them - in which case, solving the problem may involve a whole or partial repiping of the home's supply system. Other possible causes of whistling are new valves, partially closed valves, air bubbles in the supply lines, or internal plumbing hardware that is defective, damaged, or worn out. 

Pipes That Go 'Bump' In the Night - Water Hammer

Perhaps the most nerve-wracking of all pipe sounds is the banging or knocking sound that goes by the name "water hammer." Also known as hydraulic shock, this startling phenomenon occurs when the momentum of the water in a supply line is abruptly halted, as when a valve closes rapidly. This causes a massive pressure spike inside the pipe, sending a shockwave through the system and producing the signature banging sound that has scared the dickens out of countless homeowners.

Water hammer may be caused by excessive water pressure or a particularly aggressive automatic valve in an appliance (dishwashers and washing machines are common culprits). Or, the home's water hammer prevention apparatus (air chambers, standpipes, or water hammer arrestors) may not be working properly. Water hammer can degrade valves, pipes, and pipe fittings over time, giving rise to leaks or ruptured pipes - so it's best to contact a pro who can diagnose and resolve this issue quickly to avoid a plumbing nightmare!

About Magic Plumbing

Magic Plumbing has been serving San Francisco, CA and the Bay Area for over 40 years. Their friendly expert technicians always arrive on time in fully stocked trucks and go over pricing and job details up-front, so there are no surprises. Magic offers free estimates, same-day service, and membership perks. Call now for plumbing help!

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