Consequences Caused by Inadequate Sump Pump Systems

Basement flooding is unfortunately a common occurrence, often with devastating effects. The number one reason for basement flooding is the failure of a sump pump system to effectively function. Unless properly designed, a typical home’s sump pump system failing is not a matter of if but rather of when.

There are several causes of sump pump system failures which lead to flooding:

  • Excess wear and tear of the primary pump, which can ultimately burn out a light duty sump pump motor (commonly installed in new homes)
  • Switch failure
  • Power outage
  • Insufficient pumping capacity which prevents the primary pump from keeping up with water intake even though continuing to run
  • A partially or completely depleted battery of a backup system because of insufficient stored power from the system’s battery, or batteries.

Purchasing the Best Primary Sump Pump

Builders often install a lesser quality primary pump to keep costs down. Such pumps have lower pumping capacities and/or may not meet the heavy duty specifications required for a sump system. Most homes are not sold because of the quality put into the sump system. If the home has the original primary sump pump, it is probably prudent to replace it with a heavy duty AC primary pump.

Many heavy duty pumps have the switch built into or onto the body of the pump, which typically limits the discharge stroke to 2-4 inches. This limits a pump to discharging 2-4 inches of the water level from the sump pit per cycle. A way to overcome this drawback is to select a pump which can be piggy-backed off of an externally mounted switch. The switch can then be mounted onto the discharge pipe. This set-up allows the stroke to be lengthened to discharge up to 4-8 inches of the water level per cycle. This reduces the number of times that the pump has to activate, which should result in the pump motor and switch having a longer life. In addition, a piggy back remote switch can also be replaced independently of the pump (unlike those built into the pump).

Roy Spencer of Perma-Seal Basement Systems in Downers Grove, IL now only uses remote, piggy back switches when installing an Emecole Sump Pump. “Not only do we believe that this doubles the life of the system,” says Spencer. “It also reduces the amount of energy required per discharge cycle, extending the working life of the battery during a power outage. When practical, we also add a larger pit to further increase the total discharge per cycle.”

The capability or capacity of a pump under the conditions being run is dependent on a variety of factors. Most basement sump pumps are rated at both 0 feet of head and 10 feet of head. The number that is most useful is the 10 foot head capacity, as this covers how it is used in a typical basement (8-10 feet high). Another factor to keep in mind is the number of turns the discharge pipe undergoes. One 90 degree turn is ideal. The head capacity significantly drops with each turn. If the discharge is much beyond the basement exit point, increase the diameter of the pipe. Each of these factors should be kept in mind when specifying or picking out a sump pump. Most systems require a heavy duty pump with 1/3 to 1/2 horsepower (in many areas, 1/2 HP is code).

The Added Assist from a Battery Backup Sump Pump System

Installing a battery backup system creates a huge safety net during a storm. It can provide both pumping capability during power outages and also in the event that the primary pump just ceases to operate. It can also assist a functioning primary pump which is pumping but not keeping up with water intake even though there is no power outage.

When specifying a backup pump system, the homeowner or contractor should select a pump that meets or exceeds the performance of the primary pump. The performance rating of a typical 1/3 HP primary pump is around 2100+ Gallons per Hour and that of a 1/2 HP is 3000+ GPH. If the primary pump is active during ordinary conditions, the secondary pumping capacity should be increased over that of the primary pump’s capacity to account for the additional water intake during heavy rainfalls.

To match up the performance of a primary pump in a sump system with a battery operated backup system almost always requires the backup system to be based on a low amperage- drawing AC pump connected to an inverter/charger and linked to a DC battery source (AGM batteries being the best). Such a system performs its discharge capability constantly during a power outage as long as the battery or batteries have power. What this means is that, for example, if the AC back-up pump is rated as discharging at 2100 gallons per hour it will do so at this rate as it draws its power source from the battery or batteries. If the projected depletion of the batteries is four hours, the homeowner can expect his or her system to discharge up to 8400 gallons until it needs to be recharged.

The same cannot be said for most back-up systems based on a DC pump. Most DC back-up systems when drawing their power from a battery or batteries will have their capacity decrease as the battery/batteries are depleting the stored energy. Thus, if the system is rated to pump at 2100 gallons per hour it will average only about 1050 gallons per hour over the working life of the battery/batteries (considerably less than the typical capacity of a 1/3 hp primary pump). If the desired discharge rate is 2100 gallons per hour, it will only have the needed capacity in the early stages of the battery usage (and this is assuming that the battery/batteries were fully charged).

A backup system based on an AC pump rather than a DC pump is also often selected typically when the system consists of only one pump. This pump operates as the primary pump with the capability of running off both AC and battery power. This is common in situations where the homeowner and/or contractor cannot justify the extra plumbing needed to add a second pump to an existing system, or when the pit is too small to handle a second pump. An AC based system (whether one or multiple pumps) may also be chosen when the pumping requirements exceed the capacity of available DC pumps. A DC based system works best when there is little concern to how much protection is needed, and the lower cost is paramount. If optimum protection is paramount, be very wary of stated capacity of DC systems, as they are often overstated. Request an independent verification of the capacity. For more information, visit our Sump Pumps section for a complete selection of Emecole’s Battery Backup Systems.

A critical element in backup systems is the battery or batteries used during a power outage. It is highly recommended that an AGM battery be used instead of a conventional marine deep cycle, wet lead-acid or gel battery. An AGM battery typically lasts longer, out-performs these other types of batteries, and requires no maintenance. It removes the homeowner’s burden of having to frequently check the performance capability of the battery. Roy Spencer, president of Perma-Seal Basement Systems (which services the basement repair market in the Chicago area) says, “Before we switched to offering AGM batteries with our backup systems, the major call back reason we encountered was batteries that were not working during a power outage. Supplying a no maintenance AGM battery has eliminated such calls.”

There are other reasons besides power outage which call for the operation of the backup pump system (i.e. primary pump switch failure; burned out primary pump motor; primary pump under-powered for the weather conditions). An area of concern is that most low quality backup systems can only run off battery power, and thus could deplete the battery even though AC power is available. It is best that the backup pump system works off of AC current and not the battery as long as AC is available. The system should work off battery power only when AC is not available, thus maintaining maximum battery capacity for the situation when power outage subsequently occurs.

A “see through” quiet, full flow check valve is also a good feature for sump systems. The visible chamber allows the homeowner to see whether trapped debris is preventing the proper function of the check valve. These check valves also eliminate much of the noise common to most other check valves when functioning. David Miller, marketing and product manager at Metropolitan Industries says, “We manufacture and distribute pumps and backup systems to the plumbing market. We recommend only high performance, heavy duty pumps for basement sump systems (whether AC or DC systems) and encourage the use of clear, quiet check valves to optimize the performance of our recommended systems.”


The threat of residential flooding in below grade basements is always present. Chances of flooding will decrease considerably if the homeowner takes the proper steps and follows a few prudent practices:

  • Make sure that the home’s primary pump is a heavy duty AC pump with the capacity to handle major storms for many years
  • To extend the life of the sump pump system, reduce the number of pumping cycles needed to keep the sump pit from over-flowing. A way to do this is by selecting a heavy duty AC pump capable of working off of an externally mounted switch. The switch is then mounted on the discharge piping and set up to maximize the amount of water removed from the pit per discharge cycle (4-8 inches of water level vs 2-4 inches for typical pumps)
  • Consider also installing a larger capacity pit to increase discharge rate/cycle
  • Add a heavy duty backup system to operate during power outages or in place of a failed primary pump. It should also be capable to operate along with a primary pump which is running but not keeping up with water intake
  • If using a DC pump as part of the backup system, be sure the system can run off of AC current (when available) as well as DC power (for when AC current is not available)
  • Utilize AGM batteries as the DC power source for the backup system
  • Consider installing a check valve with a clear chamber for detection of debris in the check valve (which can cause the valve to malfunction) and which also operates more quietly than typical check valves

For any questions, don’t hesitate to give us a call and speak with one of our basement waterproofing expert technicians.

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