Renovation & Design

ASK THE INSPECTOR: Why you should never unplug your sump pump

QUESTION: I read your article on sump pumps in the Free Press on April 16. I found it very informative and timely. However, I would have liked to have seen you expand on the issue of never unplugging the sump pump. There must be readers out there who question the wisdom of leaving your pump plugged in during the freezing temperatures, and burning out the motor because of frozen lines. Indeed, why wouldn't I unplug? Is there any harm done leaving it in storage in the pit until spring? I would appreciate your comment. Lorri R.

ANSWER: In an effort to keep my columns fresh and avoid redundancy, I rarely answer questions on the same topic so close together, but yours is not the only inquiry I had on this subject after the recently published article you site. With the rising waters and flood risk increasing for the second time this spring, I thought I would also provide an encore in answering your sump pump question.

In my previous comments, I made a general assumption that most homeowners who have sump pits and pumps understand that they should never be disconnected, but obviously that is not the case. The reason behind this is that the sump pump gives you protection from weeping tile water overfilling the plastic drain lines under your basement floor slab and possibly the sump pit, itself. This is much more of a concern with sump pits installed in newer homes that act as catch basins for the weeping/drain lines, but may also apply to retrofit pits in older homes, to a lesser degree. To understand this fully, I will provide a basic lesson on the function of these sometimes mysterious components of our homes.

A sump pit in a newer home, normally one built in the last 25 years in our area, will be installed to act as a catch basin for all of the water drained from the weeping tile/drainage system. This system of corrugated plastic pipes collects excess ground water from outside the foundation and directs it toward the sump to prevent seepage and excess hydrostatic pressure at the foundation and footing.

In other words, the weeping-tile system keeps your foundation dry and prevents damage from soil pressure. The plastic piping outside the foundation, installed near the bottom of the foundation, is perforated with small openings that collect excess groundwater during rains and spring melts. This water is normally directed through the footing, below the foundation walls, into non-perforated plastic drain piping installed in the substrate below your concrete basement floor slab.

These pipes are gradually sloped toward the sump pit to drain the weeping tile water by gravity. The plastic weeping tile pipes terminates inside the pit, allowing the water to drain to the bottom of the sump, well below the floor slab.

A sump pump is installed near the bottom of the pit, which is equipped with a float or pressure switch that will engage the pump once the water reaches a certain depth, normally below the bottom of the weeping tile terminations. This electric pump will be connected to rigid ABS plastic piping that directs the water, through a small opening near the top of the foundation, to the exterior. This discharges the water above the ground outside the house, so that it can safely drain away from the home and foundation.

The reason that you should never unplug your sump pump is that water can drain into the sump pit at any time, even in the dead of winter. Even if the ground is snow covered and is frozen a metre of so below the surface, it may not be near the footing or bottom part of the foundation.

I have many clients and callers that tell me their sump pump runs periodically all year round, which is likely due to unfrozen soil around their foundations and high water tables. Also, we normally experience one or two periods of warm weather in the middle of a typical winter where snow will melt, and often cause additional seepage into the weeping tile system. If your pump is unplugged in either of these situations, the consequences can be disastrous.

In the worst cases, enough water can flow into the sump pit to overfill the top of the weeping tile terminations and even the pit, itself. This water can cause a mini-flood in the basement if it overspills the top of the sump.

Even if this doesn't occur, having the non-perforated drain lines under the floor slab completely filled with water can cause them to heave and crack and push up on the concrete. This can cause significant cracking and damage to the floor slab and interior basement walls. While this seems like an unlikely scenario, I have seen this occur in several homes where drains were blocked or pumps damaged or disconnected.

To further illustrate the need to keep your pump plugged in at all times, the duplex electrical outlet is required to be on a dedicated circuit. In plain language, that means that the outlet installed for the sump pump, as required by the Building Codes, must be the only thing attached to a specific circuit breaker in the electrical panel. That's required so that the circuit-breaker does not accidentally get tripped by any other device or appliance, preventing the pump from going on when needed.

If the officials who create the building codes feel that it's important enough to have constant power to your sump pump, you know it is critical.

As for your concern of a frozen sump-pump hose causing the pump to burn out, which is a very legitimate worry, the solution is simple. Most new sump-pit lids come with a brightly coloured sticker that states, "sump pump discharge hose must be disconnected at the exterior in the winter to prevent freezing". If they also included, "and sump pump should always be connected to a dedicated electrical outlet except when servicing", the advice would be complete.

Adhering to these two small principles, and annual testing of the pump, will prevent a serious problem associated with the sump pump and weeping-tile system.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the 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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