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How Many Sump Pumps Do I Need?

How Many Sump Pumps Do I Need
How Many Sump Pumps Do I Need

Addressing the obvious question first, how many sump pumps should be in 1 Sump Pit? Meaning, you have a pit, how many pumps should you have? The answer is 2:

  • Primary Sump Pump
  • Battery Backup Sump Pump

The reason for 2 sump pumps per pit is to ensure you have a fail-safe in case the first one, or your home’s power fails. Now, if you have a whole-home generator, the battery backup can be replaced with a secondary Primary Sump Pump. Your power is obviously fine at that point and the concern is having a backup pump for when, not if, your primary goes out. Because that is always the kicker, these things do not last forever.

The Bigger Question

Now that we have the semantics out of the way, we know that each Sump Pit needs to have two (2) Sump Pumps. However, would a 7,000 SF house have the same Sump Pit as a 2,000 SF house? The realization that just hit you is the same many of our customers have when we explain why our quotes are different from others.

To understand the need to have a secondary Sump Pit (and in rare cases a 3rd Sump Pit), we must first understand how a Drain Tile is installed. Luckily, we have a blog for that! See the below link to learn about grading the Drain Tile the same way Sewer Pipes are graded:

Does Drain Tile Need to be Sloped?

Now let’s assume you actually read the above blog and not just skipped to this sentence. To sum up, the Drain Tile needs to be sloped 1/8” per linear foot. Once your basement perimeter gets to 160 linear feet, a secondary Sump Pit is needed. This is because at that point, the Drain Tile will end up below your home’s footing of the foundation. This can cause the dirt underneath the footing to wash out into the Drain Tile, causing structural damage to your home! EEK!!

Educate Yourself

Here is where the tricky part comes into play. Our desire to pay less for what we perceive as the same service. Let me paint you a picture:

1.      You invite 3 contractors into your home. One happens to be us. Your perimeter footage of the foundation is 180 linear feet. By our calculations above, we need to have a second Sump Pit in order to manage the water efficiently without causing structural damage.

2.      Here’s the problem, the other 2 contractors that came out did not quote the Secondary Sump Pit, and furthermore, they denied the need for it. On top of that, the extra cost for a Secondary Sump Pit, Sump Pump, Battery Backup, Discharge Line, and Electrical Outlet. That is a lot of stuff to add on that the others were not! Who wants to pay thousands of dollars extra when you don’t have to? Nobody, and rightfully so. The issue here is that the Secondary Sump Pit IS NECESSARY.

3.      So what do you do? The obvious answer is you have 2 contractors saying the same thing and 1 saying something else. Both the others are cheaper, so we naturally want to decide which of the 2 other contractors we are going to use, dropping the most expensive quote.

4.      Fast forward to the deluge, monsoon rains we have been having, and your basement floods. Watch the excuses, screened phone calls, claims the pump is not big enough, gutters are an issue, blah blah blah. Now you’re kicking yourself because adding a Secondary Sump Pit is not that easy. Remember that the Drain Tile is sloped, so water is already flowing in one direction. You cannot just drop another Sump Pit on the other side of the basement and “hope” the water makes its way there. It will not. The whole system will need to be re-done. Which is cheaper now?

Do Not Be Bullied

Many of the companies around the country that perform these services subscribe to a “High-Pressure Sales” Process. To make clear, we DO NOT use this, DO NOT agree with it, and DO NOT respect it. However, it is out there and we need to address it.

A good rule of thumb is that if someone is asking you, repeatedly, to do something you are not sure of, do not do it. They will offer you hundreds, if not thousands off in order to get you to sign right on the spot, Glengarry Glen Ross style. Anyone telling you that you need to sign on the spot is not there for you, at all. They are there for one thing and one thing only, a commission.

WHEN you run into these and you pose the above question about needing a Secondary Sump Pit, listen to their words. When you mention the 1/8” slope per linear foot, do they recognize it? Or have you just had your first encounter with a sales rep that knows nothing of the work they are selling you? A few pointed questions will tell you the answer, real quick. Show them your knowledge!

Summing Up

To make it clear and easy, I’ll sum up the lessons from today in bullet points below:

  • Drain Tile Systems 160 Linear Feet and longer need a Second Sump Pit
  • Each Sump Pit should have 2 pumps, a Primary and a Backup (whether it be a battery backup, or in the case of a home-generator, a secondary Primary)
  • Drain Tile needs to be sloped 1/8” per Linear Foot
  • Incorrectly installed Drain Tile and inadequate Sump Pumps and Pits will cause your basement to flood
  • A Second Sump Pit cannot just be added to an existing system, as the Drain Tile is graded and needs to be re-graded towards the new pump as well. The whole system needs to be re-done

Thanks for reading, and as always:

“Not Everything’s Better When Wet”


Austin Werner

Austin Werner is the Owner of The Real Seal LLC, a basement waterproofing and foundation repair company. Austin believes that having a highly trained and happy team is the key to success. This is reflected through hundreds of 5 star customer reviews his company has received online.

4 Responses

  1. We have a basement water issue with our rental property (purchased 9 months ago) since the historical flash flooding few weeks ago. You must have seen St. Louis on the news, and that’s where are property is. We not have standing water but did have to rip-up and discard carpet/pad, and now in the middle of scrapping up old linoleum tile that we did not know was underneath! This is a half finished basement with dividing wall/door into laundry room. Water came in through front corner of finished basement, and back corner of laundry room unfinished basement where water pooled behind a stairwell retaining wall basically as a waterfall midway through mortar and through bottom of outside basement entrance door. Do we need 2 sump pumps? One in front part of finished basement, and one outside at back of retaining wall? Thanks for your input!!

    1. Hi Jane!

      Yeah, that is some scary flooding, sorry you are dealing with that. Does your basement currently have a sump pump and drain tile system? If not, that would be the place to start. We always recommend 2 sump pumps; one primary and one backup. The split between finished and unfinished doesn’t matter as much as long as they are on the same level. If your perimeter of your basement is over 160 feet, you will need a second sump pit as well with 2 more pumps. A wall covering is also highly recommended.

      For the exterior stairwell, I would say that you should have a grate drain(like the drains you see in front of parking garages) installed there to move the water to your sump pump. I am not sure of the code in St. Louis, but be sure that sump pump discharge brings the water well away from the home (at least 20 feet).

  2. What footer dimensions does the 160′ assume? I have original blueprints of our house and found the footer dimensions are 6″ x 20″. Since they are only 6″ deep and the drain tile cannot go below the footer, does the 160′ still apply to us? Or would it be less and we would need more sump pumps? Our basement perimeter is ~150′. Thank you for the helpful article!

    1. Hi Jaime!

      Great question! Most footers are between 6″ and 10″ deep. Yours seems to be on the low end, however with 150′ split in to (2 runs of 75′ going to the pit) I believe you will be okay with the one Sump Pit. We would still recommend a battery backup secondary sump pump as well, of course.

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