Crawl Space Sump Pump Install

Sump Pump Install

Like many cabins and homes built in the 1950s, our cabin has a dirt crawl space. And, like many dirt crawl spaces, ours is a damp, musty, fairly disgusting place.

The first time I ventured into our cabin crawl space, there was standing water in the space. Not good. Knowing that the ideal crawlspace mimics that of the conditioned living space of your home, I knew I had a lot of work to do, and that a sump pump install was just the beginning.

The perfect crawl space is clean, dry and sealed. Ours was not. To remedy our sick crawl space, I planned to first address the standing water and after, install a vapor barrier over the crawl space to further reduce moisture and soil gas transmission into our living space.

Crawl spaces often have several reasons for excess moisture. Our crawl space was no exception. The floor of the space was very close to the existing water level, we have no rain gutters on our cabin, and much of the yard slopes improperly toward the home. All of these issues need attention, but to start, I plan to add a sump pump to get the current water out of the space.

Common Causes of a Wet Crawl Space or Basement:

  • Floor of space lower than ground water level
  • Roof run-off and rain entering space (no gutters, blocked or leaking gutters, slope issues)
  • Condensation of moisture from humid air in space (ventilated crawl spaces, condensation on cool surfaces or ducts)
  • Lack of moisture barrier between soil and space
  • Leaking plumbing
Water sources that can lead to a damp, musty crawl space.

Common causes of a wet crawl space.

The above illustrates many of the issues contributing to our damp crawl space. Installation of a sump pump is a fairly straightforward project. Read on to see how I installed a sump pump in our cabin crawl space.



How to install a sump pump

Preparation and Materials

Project Overview

  • Level: Intermediate
  • Time: 1 – 2 Days
  • Cost: $300 – $500

Project Big Picture

  1. Plan placement.
  2. Dig sump pit.
  3. Dig / Place drain tile (optional)
  4. Place sump basin.
  5. Place sump pump in basin.
  6. Install sump pump plumbing.
Materials – Sump Basin, Pump and Drain Tile


ItemWhat I used
Submersible Sump Pump
20 gal Sump Basin
Sump Basin Cover
Check valve
Drain Tile PipePerforated pvc drain pipe used for drainage into sump pump in crawl space.
Sock Covered
Perforated Drain Pipe
(could use instead
of above)
Socke covered 4" perforated drain pipe to use for drainage tile to sump pump in crawl space.
1 1/2″ PVC DWV Pipe1 1/2" PVC schedule 40 pipe used for plumbing sump pump and sump pump discharge circuit.
River rock aggregateRiver rock aggregate used in crawl space around sump pump.
Pea gravel aggregatePea gravel aggregate used over sump pump area in crawl space.
Sump Pump Install – Tools / Supplies
  • Shovels, hoe, rake and similar tools to dig sump pit, trenching for drain tile and aggregate application and leveling
  • Hand tools to pipe discharge, mount hangers, install basin
  • Hole saw or similar to cut drain pipe access holes in sump basin
  • Tools for PVC discharge pipe circuit install
  • Drill, hammer for installing foundation pin fasteners
  • Tools, supplies for PVC circuit install
  • Bucket(s) or similar for dirt removal

How to install a sump pump – Step by Step

  1. Organize tools and supplies.

    Gather sump basin, sump pump, sump check valve, drain tile, aggregate, tools, plumbing materials, and light source.

    Sump pump, sump basin and river rock ready for crawl space sump pump install.

    River rock aggregate, sump pump check valve, submersible sump pump and sump basin.

  2. Prepare crawl space.

    Access your crawl space and remove debris, old lumber, and trash.

    Crawl space access and removal of crawl space debris.

    Crawl space access and removal of crawl space debris.

  3. Choose sump basin location.

    Survey the crawl space to determine the best sump basin location. In general, locate the basin in the lowest portion of the crawl space where water tends to accumulate in the space.

    In addition, consider a location that allows for easy access, unit servicing and drain tile connections. For this project, I located the sump at the lowest point in my crawl space, where I had previously found standing water.

    A peak inside the damp, low corner of the crawl space prior to sump basin and sump pump install.

    Target the lowest point in crawl space for sump basin location.

  4. Plan drain tile layout if using.

    Drain tile pipe is not necessary for a sump pump system, but using it will allow quicker drainage from a larger capture area.

    In order for your sump pump setup to move water out of the crawl space, water must have a way to enter the sump basin. A simple system could just use an open sump pit or basin installed below the desired water level that allowed water to flow into the top of the basin or pit and pumped out via the sump pump.

    But, for practical purposes and safety, most sump pits will use a lid to cover the basin. Holes can be drilled in the cover or sides of the basin to allow water to enter while still providing the benefits of a “covered” system. In this install I did drill holes in the lower portion of the sump basin to allow water next to the basin to enter.

    Drain tile can be added to the system to help drain more distant areas and carry that water back to the sump basin. To set up drain tile, consider which areas of the space you would like drained and plan to install corrugated or solid drain tile from that area back to the sump basin.

    For this project, most of the water was concentrated at one end of the crawl space, so I started with installing drain tile just in this area. The corrugated drain pipe tile system I used will easily allow expansion of the system later if I so choose.

  5. Prep for sump basin and drain tile install by digging a hole for the sump basin and trenches for drain tile.

    When digging, oversize the trenches and sump hole to allow for aggregate placement under and around the basin and drain tile pipe. This aggregate bed will encourage water passage into the tile and sump basin (if the basin has holes to allow water entry).

    Consider drilling holes in the side and bottom of the sump basin to allow for direct water drainage into (and out of during dry periods) the sump basin. Once the sump basin pit is dug, dig trenches for any drain tile you plan to lay and remember to slope drain tile trenches toward the sump basin.

    Digging pit for sump basin in crawl space.

    Dig a sump basin hole and trenches for the drain tile pipe.

    Trench drain tile parallel to the foundation wall, 12 – 18″ away from the foundation. Dirt should not be disturbed next to foundation walls or footings and do not dig under these structures.

    Foundation wall forces are distributed in parallel and at angles to the wall and its footings and undermining foundation wall support can compromise your structure and risk structural collapse. Generally, you should stay the same distance away from the footing as the height of that footing.

    Contact a structural engineer if you have any concerns when digging in your crawl space — this is important!

  6. Prep sump basin.

    If not already present in your sump basin, cut access holes for the drain tile pipe into the sides of the sump basin. My sump basin did not have pre-cut holes, so I cut these with a heavy duty drill and appropriate size hole saw bit.

    You should also check that you can get the sump basin into the crawl space through the access you have. In my case, the access was too small for a full size sump basin. I needed a way to get it into the crawl space, and decided to cut the basin into two halves and re-assembly once in the crawl space.

    Sump basin cut pre-install to fit through access into crawl space. Notice strips of 1/4

    Sump pump basin cut to allow passage into the crawl space through the narrow foundation access.

    Pre-cut sump basin trial assembly.

    Sump basin cut pre-install to fit through access into crawl space. Notice strips of 1/4″ aluminum strapping secured with stainless steel sheet metal screws and waste discs from the hole cutouts used to attach halves during assembly.

    To allow for re-assembly of the sump basin, I attached 1/4″ aluminum stock and the waste discs from the tile access holes (they work perfectly as their profile matches the curve of the basin) with stainless sheet metal screws to one of the two halves prior to placing it in the crawl space.

    If you are planning to drill holes in the sides / bottom of your sump basin, do it now. Drilling holes in the bottom allows the basin to drain if the water level falls below the level of the basin.

  7. Install drain tile and sump basin.

    Top ay down several inches of aggregate in the base of the sump basin hole and at the bottom of the drain pipe trenches. Aggregate can be anything from sand to gravel. Smaller aggregates are likely to be more stable, but tend to get into the drainage pipe and sump basin.

    I used small river rock and pea gravel, and covered the drainage holes on the drain tile pipe with aluminum screen to help keep the aggregate out of the drain pipes and sump basin (you can also buy filter sock covered corrugated drain tile). When installing the drain tile pipe, slope it toward the sump basin and pass it through the basin access holes several inches to allow it to drain into the sump basin.

    Sump basin and drain tile install in crawl space.

    Sump basin set on and in a layer of small rock aggregate. View of drain tile pipe set on layer of small rock with drain holes covered with rust-proof screen.

    Once the drain pipe is installed and passed into the sump basin, cover drain tile pipe with aggregate (I used pea gravel) to bring it level with the surrounding dirt.

  8. Install sump pump.

    Place the submersible sump pump in the sump basin.

    The sump pump will sit in the bottom of the sump basin and discharge the accumulated water that enters the sump basin. Most pumps are activated by a float trigger and will not pump until the water level in the basin is high enough to trigger this float switch.

    Prior to placing the pump in the basin, I attached the discharge PVC pipe to the pump, as this is much easier to do prior to the pump being placed in the basin. This pipe should be long enough to pass through the sump basin cover and allow for connection of a union / check valve.

    Additionally, most pump manufactures recommend drilling a drain hole (3/16″) in the discharge pipe, at a level just above the top of the pump (Read the install documents for your pump). The purpose of this hole is to allow drainage of the discharge system after the pump stops.

    Install submersible sump pump in sump basin in crawl space.

    Sump pump resting in sump basin with discharge pipe in place.

    Prior to setting your pump in the sump basin, you should clean out any aggregate that has found its way into the sump basin.

    Once the basin bottom is free of rock and the discharge pipe is attached, simply lower the pump to rest on the bottom of the basin. The pump is not attached to the basin, but the weight of the pump and the plumbing attachments will keep the pump stable.

    Set sump pump in bottom of sump basin.

    The sump pump simply rests in the bottom of the sump basin

    You may need to adjust the position of the pump once the sump cover is on and the plumbing attached to ensure the pump sits flat on the floor of the basin.

  9. Attach sump cover and connect sump discharge plumbing.

    Pass the discharge plumbing stub through the sump basin cover.

    Attach this discharge pipe to a combination union and check valve (green valve in photo below) and plumb the remainder of plumbing for the discharge circuit. The rubber fitting of the union / check valve prevents back flow into the sump and provides a break point for the discharge plumbing.

    Next, pass the power cord for the sump pump through the basin cover (use supplied rubber seals for the cord) for eventual connection to a suitable power supply. Secure the sump cover with supplied bolts /screws. (Many covers ship with a rubber seal that should be attached to the underside of the cover before attaching to basin top.)

    Sump basin, sump basin cover with combo union/check valve and pvc discharge plumbing.

    Sump basin cover with discharge pipe ready for connection to combo union / check valve.

  10. Install vent plumbing and connect power cord.

    De-watering sump systems should be vented and venting may be required by state and local plumbing codes.

    To vent the sump basin, I used the same 1.5″ pvc pipe and incorporated a rubber coupling to serve as a disconnect if needed. The vent pipe simply needs to pass through the sump cover and vent the basin to the outside air.

    Sump basin, sump basin cover with combo union/check valve and pvc discharge and venting plumbing.

    Sump pump cover attached, discharge and vent plumbing complete.

    Once both the discharge and vent are in place, run them to the desired point to pass them through to the outside of the house.  I ran the plumbing for this project allow the floor joist and through the rim joist to the outside of the craw space.

  11. Finish ground work around sump basin.

    Using aggregate (pea gravel), I leveled the ground over the drain tile and around the sump basin to encouraged rapid water drainage.

    Sump basin, sump basin cover with combo union/check valve and pvc discharge and venting plumbing.

    Aggregate field over and drain field area drains quickly and does not hold water.

  12. Complete plumbing passing it outside the crawl space.

    To pass the plumbing out of the crawl space I drilled holes through the rim joist using a heavy duty 1/2″ drill fitted with a hole saw bit and bit extension.

    Once the plumbing was passed to the outside, I added a rodent screen (pvc drain guard) to the vent circuit and a right angle hose attachment fitting to the discharge circuit to temporarily direct discharge water away from the house.

    Eventually, I will create a drain system for use with the rain gutters that I can direct this discharge water to as well. To finish, I sealed the passage holes with exterior caulk.

    Hole saw with extension used to pass through rim joist for sump pump plumbing and venting.

    Heavy duty 1/2 inch drill and hole saw bit with extension to drill through rim joist.

    Sump pump discharge plumbing and vent outside of house.

    Sump pump plumbing and vent passing through rim joist out of the crawl space.

  13. Connect pump to power supply.

    Check the requirements of your pump, but most pumps will require a 20 amp circuit and should have ground fault circuit interruption (GFCI) protection. The GFCI protection can be at the receptacle or at the circuit breaker.

    I wired mine with a GFCI circuit breaker to allow for easier re-setting of the circuit if needed. For the 1/2 HP pump I’m using, I wired a dedicated 20 amp GFCI circuit to use for the pump. I also added a utility light for the crawl space from this circuit.

    Crawl space 20 amp GFCI circuit for sump pump and light circuit.

    Closeup of 20 amp GFCI circuit in crawl space for sump pump, notice added light and switch. Dedicated 20 amp GFCI circuit for sump pump and utility light.

  14. Enjoy a dryer crawl space. Consider encapsulation of your crawl space.

    Switch on your power circuit (if not already on) and wait for the next downpour. Your system should be functional and will operate periodically as the sump basin fills and triggers the sump pump to empty the basin.

    With the standing water issue solved, I now plan to encapsulate the entire crawl space with a vapor barrier and active evacuation system to reduce moisture and solid gas emission and entry into our cabin



As a followup, this system was installed in the spring of 2012 and has far exceeded my expectations! This system pumped out hundreds of gallons of water throughout the spring and summer. I highly recommend the Zoeller M98 pump — it’s quiet, and more than powerful enough to quickly empty the system even during heavy rains.


Sump Pump Install Image Gallery

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  • Graham January 6, 2020   Reply →

    Jen’s question on Jan. 6, 2020, landed in my in-box (regular email, not part of this site). I’m not the author of this thread, though I’d asked a question back in 2015 that didn’t get answered. So, here’s my two cents’ worth, since it doesn’t look like the original poster is following the topic any more:

    First of all, didn’t you mean to say “… where it can rain non-stop for WEEKS.” ? (I grew up in the NW )

    Anyway, yes, a sump pump would work fine … and, yes, just run the hose out to your French drain.

    The procedure described in this thread is kinda the Cadillac version. Me, I’d do it in quick and dirty fashion:

    Find a bucket big enough to hold the pump (while not interfering w/ the float) that’s got holes punched in the bottom and on the sides around the base so that water can easily get in.

    Then, make a hole in the ground about 6 inches deep that’s big enough to hold the bucket, and line the hole with gravel. Also add a few inches of gravel to the bottom of the bucket and put the pump on top of it. (Among other things, this will keep the pump where you want it.)

    Finally, build a berm of gravel outside the bucket that’s deep enough to cover the holes that you punched around the sides. The reason for all this is to keep the water clean. Sump pumps aren’t designed to pump dirty water, and the gravel will filter it. When sump pumps are installed in new homes, the sides of the bucket holding the pump are encased in gravel (in fact, there should be gravel underneath the entire concrete pad) for the same reason.

    And unless your crawl space is sealed — literally — as tight as a drum (unlikely), no need to worry about venting. Install a reverse “U” above the pump, which will prevent water from the drain line draining back into the pump when it turns itself off. You could install an anti-drainback valve, but the U will do the same thing for much less $$.

    I suggest trying to install the pump at the lowest place in the crawl space, simply because that will keep things the dryest. But if it’s all about the same elevation, no reason not to install near the access panel.

    Have fun!


  • Jen January 6, 2020   Reply →

    Hi… Not sure if you’e still monitoring this, but thought I’d try.
    I live in the NW where sometimes it can rain non-stop for days. I recently ripped down my old detached garage that used to flood all the time and I built a new one. Unfortunately, now that water is going under my house. I can get up to 4″ of water under my home. Considering I only have about 12″ from dirt to floor beams it’s a major issue. (It’s difficult to rollover when you’re under the house). Any suggestions on what to do?
    Can I install the sump basin & then just run that hose out to my french drain? Do I still need to do the vent plumbing? Can I install it right by entrance
    Thank you!

    • Cabin DIY January 7, 2020   Reply →
      Cabin DIY

      Hey Jen,

      Yes, these threads are still monitored and active. Thanks to Graham for the insightful reply and sorry I missed your previous question!

      To add to the conversation regarding your water issue, I would like to mention a few considerations.

      1. First, if possible you should consider landscape and slope issues with your property. If much of the water under your home is run-off there are likely landscape issues you could address. Things like surface drains, french drains, proper land grading around the home, etc., are all issues that can significantly affect the conditions under and in your home.

      2. The sump should probably just be a first step. Sump pump systems can remove bulk water and greatly improve conditions under your home. But, homes build over soil crawlspaces tend to have ongoing water/moisture problems unless significant change is made to address that underlying issues with unsealed crawlspace foundations.

      A home build over a dirt crawlspace is essentially a home built directly over the soil. Imagine pitching a tent directly over your yard without a barrier cover tarp underneath it. The ground releases enormous amounts of moisture vapor depending on your geography. In addition, moisture vapor in the air tends to release within vented crawlspaces as water moisture-rich air cools within the crawlspace. Here is an excellent article discussing moisture issues and crawlspaces from Building Science

      So, if you are to significantly fix the moisture issues in your home, you will likely need to address landscape and crawlspace problems that you likely have.

      As far as a sump pump goes, as Graham explained, the function of a sump is to simply collect and mechanically remove excess water under your home. Place the sump basin where the water tends to collect. Water can be then directed out of the crawl space via PVC pipe, discharged away from the home and foundation. Many municipalities have regulations regarding sump pump discharge, so check with your local agencies to ensure you are in compliance. Also, if you live in an area with sub-freezing temps, you will need to consider the best method of sump use during the winter to avoid discharge line freeze-up.

      Thanks for the questions Jen and thanks Graham for the contributions.


  • Brice Aldrich November 17, 2016   Reply →

    Thanks for your quick response!

    Unfortunately, the spot I was considering digging is not the most convenient. There are no considerable slopes or low points, but during heavy rains you can see small amounts standing water. Would it be a bad idea to just dig the sump pump in a convenient location near the entrance, then run drain tile in the spots that sometimes show water?

  • Brice November 14, 2016   Reply →

    Thanks for the great tutorial! I just bought a home as an investment property, and it has a crawl space in pretty rough condition. Unfortunate for the crawl only has about a 2 foot clearance from the floor to the ceiling. I’d like to install a sump pump, but have no idea how I am going to be able to dig while laying on my stomach. It looks like your crawl had a low clearance as well. Any tips to make the process easier?

    • Cabin DIY November 15, 2016   Reply →
      Cabin DIY

      Hi Bruce,

      Your welcome.

      Yes, our crawl space has very low ceiling clearance as well. Luckily, the low spot in the crawl was close to the entrance and had the best clearance of around three feet, making the job a bit easier. I suspect that in most crawl spaces the same is true – the lowest (water dependent) spot in the crawl space will be the area with the best clearance, if not flat.

      If you can I would choose a spot for your sump pit that is close to an entry, allowing easier dirt removal and service later. I used a short-handled shovel, which for me worked quite well. You may need to be a bit more creative, like maybe using a garden or grub hoe. Hopefully you can at least sit or knee while digging.

      Taking a clue from commercial vacuum excavators, If the dirt is loose and dry, maybe a shop vac could help? Another option is to hire the digging out.

      No matter the method used to remove the soil, you certainly could plan for a smaller, shallower sump pit basin to limit the amount of soil to be removed.

      Good luck!


  • Graham May 22, 2015   Reply →

    First, thanks for an excellent write-up. Exceptionally clear instructions.

    I own a house that I bought three years ago after flash flooding (approx 18 inches of water above-ground) caused substantial damage to many houses in the area. In my house, the crawl space completely filled with water (through the vents and below-grade access opening). After the flooding eased (within a few hours), some water drained out through the foundation vents, but the crawl space below the vents was still full of water (I’m estimating about two feet deep).

    The then-owner managed to drain the crawl space (not sure exactly how, but not that important). What I would like to do is install a system that could be used to drain the crawl space in case of another flood. This is fairly unlikely — such an event seems to come along approx once every 20-30 years, but with climate change, who knows? So I’d like to be prepared, instead of trying to buy a pump or hire a remediation service after the flood, when thousands of other people are trying to do the same thing.

    I’m NOT expecting to prevent the crawl space from filling up with water if the flood level comes higher than the vents. But after the flooding eases, I’d like to be able to flip a switch and have a pump go to work.

    Normally, I don’t need even a sump pump — the crawl space stays dry as a bone.

    So my question is, which would be better — a sump pump or a “dirty water” pump? Should I go to the trouble of installing a proper drain sump (like you did), or just make sure I have a pump that I can toss in after a flood and start pumping? Or, would I be better off encapsulating the crawl space to prevent flooding in the first place?

    Thanks for any advice.

  • Chris January 28, 2015   Reply →

    Can you use that dirt to cover other holes in the basement ? What is the reason that you have to remove it?,thanks

    (Sorry I meant to say why does it have to be removed from basement)

    • Cabin DIY January 28, 2015   Reply →
      Cabin DIY

      Hi Chris,

      Good point. You do not need to remove the dirt from the sump pump basin hole.

      I did remove the dirt because I planned to encapsulate the crawl space after I installed the sump. My crawl space is very tight, and it seemed to make sense to remove the dirt rather than keep it in the space. Also, the dirt from my digging was very mucky and stinky.

      Thanks for the comments.


  • WT Langston August 3, 2014   Reply →

    It looked like you had foam insulation on your walls. Do you still have open venting? Also, do you have a vapor/moisture barrier on the floor?

    • Cabin DIY August 3, 2014   Reply →
      Cabin DIY

      Hi WT,

      I do have spray foam insulated walls. I closed the venting by replacing the block and using urethane caulk to seal around the block (instead of masonry mix in case I wanted to remove the block in the future for access or other). I talk a bit about it in my article on installing a crawlspace vapor barrier.

  • John Russell May 31, 2014   Reply →

    Any tips on getting the rock into and getting the dirt out of the crawlspace without killing yourself?

    • Cabin DIY May 31, 2014   Reply →
      Cabin DIY

      Hi John,

      As for the rock, I used bagged rock from the Home Depot. Each bag weighted somewhere around 40 lbs (guess). I think the bags made it easier, but I think I used a total of 10 bags (a few of the coarse rock and more of the pea gravel). You could consider building a simple slide to deliver the rock through your access.

      Getting the dirt out is always a pain. If you have the access, a small dirt coveyor would be great. Many used 5 gallon buckets. Hiring young strong help may be worth it.

      I used a small shovel and pitched it out of the space as I dug. I had the advantage of digging very close to my access that I could pitch the dirt out through.

      Good luck. You could post a photo of your space and maybe some of our readers would have some ideas for you to consider.


  • Bryan K February 15, 2014   Reply →

    Hi there,
    I’m using the same M98 pump to replace an older one that failed in our basement during heavy rains in Seattle this week. Only question is whether or not you glued the threaded end of the drain pipe into the NPT port on the sump pump, or just “dry” screwed it into place with a threaded-male 1 1/2″ PVC adapter? I imagine just screwing it in will be fine, as the other connections above the basin are all glued or clamped to remain watertight. Thanks!

    • Cabin DIY February 15, 2014   Reply →
      Cabin DIY

      Hey Bryan –

      As this connection is on the discharge side and does not necessarily need to be air or water tight. Any “leaked” water around this connection will just spill into the sump basin, re-enter the pump and eventually be pumped out. Also, this connection is typically under the water level in the sump basin and leaks would be difficult to notice unless they were quite large.

      When I connected my pump I did not glue the connection but did use several wraps of Teflon thread tape mainly to ease the connection and potential later disconnection if needed.

      This connection is PVC to steel (the housing of the pump) and not typically glue appropriate anyway.

      Thanks for the comments and good luck with the replacement. I love Zoeller pumps!

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