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Question DetailsAsked on 1/3/2017



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2 Answers


Since sound is strongest at toilet, I would bet you have a slightly leaking inlet valve on the toilet - letting a trickle of water through the valve when it is "off". Or - you have a "running" toilet, meaning you have a leak at the tank discharge point.

Can't go into all possibilities and terminology here - for further help or terminology of parts, go to FluidMaster website and see the diagrams on their kits to rebuild toilet tank operating parts, which is also the brand I recommend if you decide to DIY. Or google "running toilet repair" for tons of articles and Youtube videos on how to diagnose and fix it yourself. Inlet valve replacement usually pretty easy, flapper replacement very easy if removeable type, flappear with base more hassle but not technically difficult. Replacing the gaskets UNDER the flapper base or overflow tube requires taking the tank off the toilet, so that is getting up there in DIY difficulty - not a first-time toilet mechanism repair task for most people.

Look in the toilet bowl - is there a trickle of water running into it from the tank (you can put dark food coloring in the tank water to see more clearly if leaking into bowl), coming from under the riminto the bowl ? Will show up (unless very small leak, which yours is not) as a ripple disturbance where the water coming from under the rim hits the water in the bottom of the bowl.

If you did not see disturbance in the water in the bowl when the pipe is humming, lift top off toilet tank (careful - tank and top are usually procelain or ceramic, so avoid bumping them together or dropping the lid - and inside of lid will be usually be soaking wet and maybe moldy, so flip upside down right away. Then watch and see if when the humming occurs there is a disturbance in the water in the tank (caused by the inlet valve opening a bit because the float dropped as water drained into the toilet). If water is not running over the top of the overflow tube and not waster is coming out of the small tube which discharges into the top of the overflow tube, then float height is OK and it is NOT a leaking inlet valve causing the water height to get too high. This is highly unlikely to be the cause because of the cyclic mode of your problem - a high float or leaking inlet valve would normally hum or hiss continuously.

IF water is going into the toilet bowl when it is just sitting (not right after a flush), you likely have a "running toilet" - a leak from the tank into the toilet bowl, which is causing the float to drop and open the inlet valve to open a bit to refill the tank. However, an inlet valve (the part the float is attached to, usually a tower at left end of tank) failing to shut off all the way can also cause this - but since yours is cyclic problem is almost certainly a leak into the bowl from the tank, not an inlet valve problem, even though the inlet valve is what is causing the noise as it opens and closes to refill the tank to replace the leaked-out water.

The "running toilet" leak cause is almost always a poorly sealing flapper valve - black or red or blue or gray or green or ??? flapper or bulb valve in bottom of tank (covering the about 2" outlet hole to the bowl that flush water goes down) in most cases, but sometimes a vertical sliding plastic tube arrangement over the hole with a gasket on the bottom or at the bottom drain hole. Whatever it is in your toilet that lifts up to let the water out when you depress the flush handle is the outlet valve. Sometimes cleaning the mating surfaces where it seals to the rim of the hole as it closes, using a paper towel or rag while holding flush lever down, removes grit or algae or mineral buildup causing the leakage. Sometimes the discharge element or its gasket (for gasket types) or flapper needs replacing because it is old and warped or torn and letting a bit of water leak out. On most toilet models just the gasket or flapper can be easily replaced (flapper commonly has a couple of pop-off "ears) that act as it's hinge), other times the flapper can be removed and replaced with a gooey caulk-sealed press-on replacement kit unit, on others but rarely the entire outlet valve portion needs replacing - usually only if the plastic parts are cracked and leaking.

Occasionally it is a leak at the base of the discharge opening at the tank or at the base of the overflow tube (commonly both are one outlet) - old gasket, which means dismounting the tank to replace that. Gently putting some dark food coloring drops underwater a few inches away from the outlet and overflow tube will show where the leak is as the coloring flows towards the leaking point.

Rarely, can be because the float adjustment has gone out of calibration and the float is set too high, so water is wicking or slightly pouring over the top of the vertical (about 1" diameter) overflow tube, causing the inlet valve to frequently open for a short time to try to make up that lost water - but more commonly this results in continuous low inlet flow and noise. If that is the case, adjust the float stop screw (on most ball and arm types) or the slide-stop on the metal or plastic rod (for most vertical float canister types) so the float sits a touch lower when the arm or bar it is attached to and lifts as water flows in reaches its high point and shuts off the inflow.

Also rarely (except just after changing components out), if the chain or cord that lifts the outlet valve or flapper is too short or gets kinked (especially common with chain types) so it is pulling on the outlet valve or flapper when just sitting there, it can slightly lift the valve body or flapper and allow a small amount of water to trickle out of the tank, causing cycling of the inlet valve.

Also, occasionally some tank slime or scrap of caulk or such will float into the outlet hole and hang up on the rim, allowing a slight leak.

Also - if water is on the floor - could be a leaking tank bolt or inlet valve gasket where it goes through the tank, or very rarely a cracked tank, allowing tank water to leak onto the floor - though with the frequency yours is cycling that would make for a pretty obvious leak in pretty short order.

Note if you have a running toilet, this can potentially (especially if cycling every minute or so like your case) use as much as 5-20,000 gallons per month - up to 100,000 or so if continuously running so it is continuously refilling - that can add up to a LOT of $ if you have metered water usage, especially in drought areas with high use penalties. If you have a real high water bill for this reason, sometimes the utility will reduce it if you can prove you fixed the leak source - with a contractor statement/bill or a receipt for toilet parts.

If unable to fix yourself, commonly abotu $50-100 for a Handyman or $100-200 for a plumber to fix it - plus about $10-50 parts depending on what part(s) need to be replaced.

Here are some previous similar questions about humming pipes, with answers, which should help if the above did NOT solve your problem - but I am pretty confident the above is your situation, especially with the periodic cycling at a regular short interval.

Answered 3 years ago by LCD



This is Erick in Member Care. Thanks for your interest in Angie's List!

We'll be happy to help find top rated Plumbers that can assist with the humming and vibrating that is coming from your pipes, but it doesn't look like you have a subscription to the List yet. You can join by visiting or by giving us a call. Our call center is available 8:00 am-9:00 pm weekdays and 8:00-5:00 pm ET on Saturdays.

Thanks for your question and we look forward to assisting you!

Answered 3 years ago by Member Services

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