Quick Answer
There are a few main reasons why a house might need two sump pumps:
- The house has a very large basement or crawlspace that requires extra pumping capacity.
- There are multiple sources of water entering the basement, like a high water table and surface runoff, so two pumps are needed to keep up.
- Having two pumps provides redundancy in case one pump fails or can’t keep up during heavy rains.
- One pump is used for typical water removal while the second handles overflow or is set up to only turn on when water reaches a certain level.
Looking at Typical Sump Pump Setup
Most houses only need one sump pump system to keep the basement or crawlspace dry. Here is a look at the typical sump pump setup:
- Sump pit – This is a hole about 2 feet wide and 1-2 feet deep lined with concrete, tile, or a plastic bucket. It is placed at the lowest point where water collects.
- Sump pump – The pump itself sits inside the sump pit. It is often sized between 1/3 and 1/2 horsepower and can move over 2000 gallons per hour. It connects to a discharge line.
- Discharge line – This pipe or tubing runs from the sump pump out of the house, often through the foundation wall. It discharges the water away from the house into the yard.
- Check valve – This valve on the discharge line prevents water from flowing back into the sump pit and flooding the basement.
- Float switch – This switch turns the sump pump on when the water level rises high enough to lift the float and triggers it to turn off when the water drains.
For a typical single-family home, one properly sized sump pump in a central sump pit is usually sufficient to remove groundwater seepage and prevent the basement from flooding.
Reasons Why a Second Sump Pump May be Needed
While most homes only need one sump pump, there are some situations where installing a second pump is recommended:
Large Basement or Crawlspace
Homes with very large basement foundations or crawlspaces may need extra pumping capacity to keep the space dry. An extremely large basement could overwhelm a single pump during periods of heavy rainfall or high groundwater. Adding a second sump pump provides extra assurance that water can be pumped out fast enough.
Multiple Water Sources
Sometimes a single sump pit in one corner of the basement isn’t enough to handle all the water. For example, a high water table on one side and heavy surface runoff on the opposite side could require one sump to handle the groundwater and another for the surface drainage. Two separate sump pump systems strategically placed allows both water sources to be managed.
Backup Protection
A second sump pump can provide critical redundancy if the primary pump fails. Having two pumps decreases the risk of ending up with a flooded basement if one pump breaks down or can’t keep up with the water flow during heavy rain. It’s a good safeguard for finished basements where flooding would cause extensive damage.
Manage Overflow
In a heavy storm, a single sump pump may struggle to keep up and the water level could get dangerously high in the sump pit. Installing a second pump set to turn on at a higher water level helps manage overflow situations. The main pump handles regular drainage while the second one provides extra capacity when needed most.
Less Strain on Primary Pump
Two smaller pumps that handle normal drainage needs can avoid overworking one larger pump and risking burnout. Smaller pumps may also allow greater flexibility in positioning sump pits optimally around the basement. Taking some of the load off a primary pump extends its life and ensures adequate drainage.
Typical Setup for Dual Sump Pump System
For a dual sump pump configuration, here are some common options for setting up the two pumping systems:
Two Pits, Two Pumps
The most straightforward approach is two completely separate sump pits, each with their own pump, discharge line, and float switch. This provides full redundancy should one pump have issues. The sump pits can be positioned at optimal locations around basement.
Dual Pumps, Single Pit
Another option is two pumps in a large common sump pit. There would still be two discharge lines. Usually, the primary pump would handle regular water levels while the second pump is wired to only turn on when the float switch hits a certain higher trigger point.
Two Pits, Alternating Pumps
Some systems alternate the pumps across two sump pits. For example, the main pump might be in pit 1 while the secondary pump is in pit 2. They can alternate which pit is active. This method ensures equal run time across both pumps.
Back-Up Battery Power
It’s also wise to install a backup battery system for at least one pump in case of power failure. This avoids a situation where all pumps are rendered useless during an outage when they are needed most. The battery kicks in to keep the system going.
Installing and Maintaining Dual Sump Pumps
Here are some tips for installing two sump pumps and keeping them maintained:
Hire a Professional
It’s highly advisable to have a dual sump pump system installed by an experienced professional. This will ensure proper placement of sump pits, correct pump and pipe sizing, as well as electrical wiring for optimal performance and redundancy.
Test Regularly
Test each sump pump monthly by filling the pits with water and ensuring the pumps activate at appropriate levels. This verifies both pumps, plus the backup battery system if installed. Catch any issues before they become failures.
Replace Float Switches
Float switches should be replaced about every 2-3 years or at first sign of problems. Floats can get stuck or weighted down with debris over time and cause pump failures.
Check Discharge Lines
Inspect discharge pipes regularly for blockages or cracks that could impede water flow. Discharge lines should exit the house at least several feet from the foundation.
Maintain Pumps
Follow manufacturer maintenance guidelines for periodic inspection and cleaning of sump pumps. Removing debris keeps them running smoothly. Lubricate pumps and check for impeller or motor issues.
Control Sump Pit Water
Minimize debris that enters the sump pits by covering pits with tight-fitting lids. Seasonal maintenance like cleaning sump pits or installing sediment filters can reduce buildup that could clog pumps.
Have Spare Floats and Pumps
Keep spare pump floats and a backup sump pump on hand. This avoids long delays if a key component fails and needs replacement when water is flowing into the basement.
Key Reasons for Dual Sump Pump System
Here is a summary of the main scenarios where installing a second sump pump is a wise investment:
– Very large basement or crawlspace footprint needing extra pumping capacity
– Multiple water sources such as high groundwater table plus rain runoff
– Desire for pump redundancy in case of primary pump failure
– Manage overflow situations and heavy rain events
– Reduce strain on a single pump and extend pump life
– Ability to position multiple sump pits optimally around basement
While the added cost of a second pump and additional installation complexity may not make sense for all homes, the added peace of mind and protection against basement flooding can make it a worthwhile investment for certain situations.
Signs Pointing to Need for Second Sump Pump
These symptoms can indicate the need to add a second sump pump to properly manage basement or crawlspace drainage:
- Primary pump constantly cycling on and off
- Sump pit overflowing during heavy rain
- Standing water in various areas far from main sump pit
- Must frequently clean and service primary pump due to overuse
- Main pump unable to keep up if drainage blocked
- No redundancy if primary pump fails
- Battery backup frequently kicking in due to primary pump maxing out
- Flooding occurs when main pump breaks or power outages happen
If one sump pit and pump struggles to keep the basement dry, carefully evaluate where any backup water is coming from and the optimal places to locate additional sump pits and pumps.
Evaluating Need for Multiple Sump Pumps
When trying to decide if a second sump pump is needed, here are some key factors to consider:
Basement or Crawlspace Size
The larger the foundation footprint, especially length and width over 1500 square feet, the greater the potential need for multiple pumps properly located in different areas.
Sources of Water
Identify all sources of water, like high groundwater table, surface runoff, foundation cracks, and drainage issues. Dual pumps can target different sources.
Pump Capacity
Evaluate the main pump size and capacity. If it is constantly working at high capacity, a second unit could take some load off and provide redundancy.
Power Loss Concerns
Frequent power losses or an inability to rely on battery backup point to the need for a second pump with separate circuit and battery.
Value of Flooded Space
For finished basements with high value, the added insurance of redundancy and backup capacity could be well worth it.
Proximity to Open Water
Nearby bodies of water, heavy rains, and a high water table increase chances of flooding and may indicate multiple pumps are prudent.
Age and Condition of Main Pump
Older primary pumps that frequently run or show signs of wear make a strong case for installing a secondary unit for redundancy.
Carefully weighing these factors allows determining whether one or two sump pumps are required to adequately handle all basement or crawlspace drainage. Most homeowners never need to think about adding a second unit. But for certain situations, dual pumps provide an added level of protection and redundancy for high-value finished basement spaces.
Typical Costs for Second Sump Pump
If evaluation indicates that a second sump pump is recommended, what are typical costs?
For parts needed:
| Sump pump unit | $100-$300 |
| Plastic or concrete sump basin | $50-$200 |
| Discharge pipe and fittings | $50-$100 |
| Check valve | $10-$30 |
| Float switch | $20-$60 |
In addition, homeowners need to factor in the cost of hiring a qualified contractor to install a second pump system:
– Average labor cost for sump pump installation: $45-$65 per hour
– Typical time for a professional to install second unit: 3-6 hours
– This puts labor costs in the $150-$400 range
So for a simple system using a medium-grade pump, basic sump basin, and PVC discharge line, total costs could be:
Parts: $200-$700
Labor: $150-$400
**Total cost: $350-$1100 for second sump pump system**
Complex installations with longer discharge lines, specialty basins, and high-capacity pumps could reach $1500 or more. But for most homes, a second basic system adequate for supplemental drainage can be added affordably under $1000.
Compared to extensive water damage repair costing potentially tens of thousands of dollars, adding secondary sump pump protection is a wise investment for at-risk homes. And peace of mind is priceless.
Conclusion
While the vast majority of houses get by just fine with a single sump pump system, there are certain situations where installing a second pump provides critical redundancy:
– Very large basements requiring extra drainage capacity
– Multiple water sources to handle
– Concerns about primary pump reliability and lack of backup protection
– Desire to manage heavy overflow during major rain events
– Chance to extend primary pump life by reducing strain
Carefully evaluating basement size, water sources, pump capacity, power reliability, and value of space can determine if dual pumps are prudent.
When properly positioned and installed using separate power circuits, second pumps provide an added layer of assurance that basement or crawlspace flooding will be minimized. For only a few hundred dollars in total cost, they can pay for themselves many times over by avoiding expensive water damage repairs and giving homeowners invaluable peace of mind.
