Renovation & Design

ASK THE INSPECTOR: How to quiet sump-pump drain-pipe racket

QUESTION: In 2005 we purchased a bungalow which was built in 1993. This was the first time we had a home with a sump pump. Our last home was on a ravine property in Ontario, and when it was being built, we obtained a variance from the town allowing our weeping tiles to drain into the ravine. We wish that were the case here.

When we moved in, we found the sump pump was very loud, so we had a large plumbing company replace the pump with what they promised was a much quieter model, as well as a battery-powered backup pump. Unfortunately, the problem continued, although they did come back and assured us that it was installed properly.

The sump pit is in the middle of the house, and when the water is pumped out, it passes over a frequently used guest room, waking guests in the night with what we think may be the water backing down the pipe once the pump shuts off. The pipes vibrate a lot and make a racket when this happens.

Do you think there should be a valve somewhere along the line to prevent the water from backing all the way down to the pit? One alternative we have is to switch the guest room with a craft room located in another part of the lower level, but this would be a lot of work due to installed counters and shelves in the craft room.

Any help you could give us to solve this dilemma would be appreciated.

John and Marlene Oldham

ANSWER: Some plumbing noises are unavoidable and others may be minimized by minor alterations or repairs. Your sump-pump drain-pipe noise is one that should be in the latter category. The check valve you mention may also be installed out of sight, or installation may improve the situation if it is indeed missing.

I'm surprised that in a home your age, the sump-pump discharge pipe actually runs over the ceiling in a basement room. This is around the age of home when most local builders began installing this ABS plastic drain pipe inside the basement floor slab before it was poured. In that type of arrangement, the end of this sub-slab pipe normally will protrude through the floor right beside the foundation walls. It would not have to travel any significant distance beneath the main-floor joists, as in your home.

Though it may be quite disruptive, you could have a channel cut in the concrete slab to allow installation of the pipe in the floor of the bedroom. That would significantly cut down on the noise factor but may not be worth the expense or effort when simpler repairs might work.

It's quite common for long runs of sump drain pipes running under the floor joists to become slightly bowed or loose because they are full of water for much of the year. A one-way check valve, installed in the drain line above the pump, allows water to be pumped outside but will shut when the pump stops, preventing a back-flow of water to the pit. This is done to prevent the expelled water in the pipe from flowing back into the sump, which may cause somewhat endless operation of the pump. This backwards flow of water could make the noise considerably worse.

If this check valve is not seen just above the sump pit or below the lid, one should definitely be installed. If it's there, then noise in the discharge pipe may be primarily due to movement. As you suggest, the vibration from the sump pump itself can be transferred through the entire length of the drain pipe when it's running. When the pump shuts off, there can be a loud banging noise as the pressure inside the pipe suddenly drops and it rubs or bumps into the surrounding wall or ceiling coverings.

In many units I've seen, the drain pipe has been very poorly secured, not only under the floor joists but also between the sump pit and the underside of the floor. Anchoring this pipe, especially the initial vertical riser, may cut down on the vibration noise considerably. To accomplish this, some wood framing may have to be installed beside the pipe to allow proper clamps or plumbing strapping to be used. Also, the horizontal length of this pipe may be poorly secured to the floor joists and exterior wall framing, allowing extraneous movement and vibration.

If the discharge pipe appears to be properly secured and is not warped or bowed, then the simple noise of the water flowing through this area is to blame. The ideal material is soft foam pipe wrapping, which is normally used for copper supply pipes but may be adapted for the larger piping. This material is very pliable and could also be installed between the drain pipe and any framing or wall coverings to prevent noise from banging due to pressure changes.

Though it could have been largely avoided by the current practice of burying the majority of the pipe in the basement floor slab, proper securing and insulation of the offending drain may help eliminate this minor issue.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and president of the Canadian Association of Home & Property Inspectors-Manitoba ( Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at



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