Hydrostatic Pressure: What It Is and What It Isn’t

Hydrostatic pressure is a critical factor that can wreak havoc on concrete structures, especially when excess moisture is involved.

Understanding what hydrostatic pressure is and what it isn’t is essential for anyone dealing with concrete slab moisture issues.

What Is Hydrostatic Pressure?

In this article, we delve into the depths of hydrostatic pressure, exploring its causes, impacts, and misconceptions. Join us as we unravel the mysteries of hydrostatic pressure and discover how to address moisture-related problems effectively.

Hydrostatic pressure is a term that is often used when excess moisture has created problems with concrete slabs and connected flooring systems. However, it is not as generic a term as people in the industry often think.

What Is Hydrostatic Pressure?

At its simplest, hydrostatic pressure is the pressure created by standing or resting (“static”) water (“hydro”). We’ve all heard the story of the little Dutch boy who saved a town from the force of standing water when a dam sprang a leak. That same relentless pressure can impact your concrete walls and floors too.

While concrete is a relatively solid material when dry, it isn’t technically solid in the same way that stainless steel or marble is. It isn’t impervious to moisture.

As concrete dries, water vapor from the original concrete mixture exits the slab, creating small capillary networks. These pathways remain open until properly sealed, and can be the path of least resistance when water pressure builds up against a concrete contact point.

While newer high-strength concretes can resist higher levels of pressure than older mixtures, they still can be susceptible if cracks form or hydrostatic pressure builds high enough.

Hydrostatic pressure is a natural force that can move rocks, buckle walls, and cause havoc with your concrete, but it does not explain every instance of water intrusion in concrete.

What Causes Hydrostatic Pressure?

Normally this happens in basement floors or floors below water tables. The more water, the more pressure you’ll have at the bottom of the water table.

Think of it like swimming; when you dive deeper, you feel more pressure on your ears. Same as hydrostatic pressure, the deeper your foundation and the wetter soil conditions, the higher the chance of moisture-related problems.

What Hydrostatic Pressure Isn’t

Hydrostatic pressure is a term often used rather generically to explain any moisture problem that occurs in a concrete slab, but more often than not, it isn’t the culprit. Several other sources of moisture could equally be responsible for water intrusion or moisture-related flooring issues.

Hydrostatic pressure, by nature, does not occur in slabs above grade. It does not even occur in every slab below the soil line. For a concrete slab to be impacted by hydrostatic pressure, it must be below the water table on the site or intrude into a natural water pathway.

Water, underground as well as above, moves downhill under the pull of gravity, and so sites cut into a hillside stand a greater risk of having the “hillside side” be affected by hydrostatic pressure if adequate steps to redirect the water (and the subsequent pressure that might build up as it accumulates) are not taken.

Poor drainage may cause water to collect against a concrete foundation but generally will not build up the volume to cause problems attributable to hydrostatic pressure.

Free Download – 4 Reasons Why Your Concrete Is Taking Forever to Dry

Only identifying the correct source of excess moisture will make proper remediation possible.

Other possibilities include:

  • Water Supply Sources
    Sprinklers, plumbing, city mains, and other water supply lines may be a source of moisture if they break or if a joint fails. If this occurs in a location with poor drainage or very dense soil, the water may end up in extended contact with the concrete and increase its internal moisture content, or relative humidity (RH).

    The pressure formed by a burst pipe is technically a type of hydraulic (or a mechanical force) pressure.

  • Inadequate Installation
    Educated WorkersObviously, we want to believe that every concrete and flooring professional is fully educated in his or her trade and uses the strictest standards to be sure each job is completed correctly. Unfortunately, the high level of flooring failure costs annually suggests that there is more to be learned.

    Some installation culprits that can result in excess concrete slab moisture may include a vapor retarder with insufficient or poor “perm” (permeability) rating, insufficient site evaluation or geotechnical survey to identify natural water sources, excessive troweling that prematurely seals the slab surface, or surface membranes applied before the slab was adequately dry.

  • Improperly Dried Concrete
    In cases where flooring failure is attributed to excess moisture, it is important to be sure that the slab was adequately dry before flooring was installed. Installers intent on meeting a construction deadline, or those who use surface-only test methods like calcium chloride testing, may not have had accurate moisture content data to base their adhesive or flooring material choices on.

    Only RH testing can adequately determine the true moisture conditions of a concrete slab and inform both schedule and flooring decisions.

Ultimately, if hydrostatic pressure is the culprit, the only way to correct it is to eliminate the pressure of standing water, a significant undertaking in any situation.

However, accurate and comprehensive moisture testing and site evaluation can indicate the true source of concrete moisture intrusion to ensure proper and lasting remedies.

Learn more about the real dangers of hydrostatic pressure.

Last updated on February 28th, 2024


  1. Tom gilles says:

    Hello Jason,

    I built my home back in 1993. I had an unfinished basement for approximately 7 yrs. I decided to finish it off. I live on an area with a high water table. The soil is clay. I have a walk out lower level. Many people in this neighborhood over the years have had some sort of water issues in their lower levels. Not me. I pick this lot because it didn’t have water on it like others in this area. During the building process I took many pictures of the lot to the finished product. They put approximately 6 to 8” of pee gravel down on the ground under my slab in my lower level. No drain tile. I do have a sump pump basket which runs normally during wet months. It has slits in it. Last January 2021 wouldn’t you know it I started getting some water in the middle of the floor in my lower level. Mind you NEVER in the whole time I have lived here have I ever got water anywhere. It lasted 2 weeks and came from the same spot. It went away until this year in January almost to the same week and I got water again from the same spot. It’s been going on a week and a half but appears to have dried up again. What the hell is going on? I called the city engineer who is my neighbor and he referred me to a hydrologist that works for the city. He said it could be frost in the ground causing great pressure on the high water table and it caused water to push up underneath your slab. Hydrostatic pressure. Why would it only last for a couple weeks then it’s over. Dry the rest of the year. Any suggestions? Will it go away? I have had 3 cos. Come out and say drain tile in that area to the sump basket but no guarantee it will work. Any answers?

    • Jason Spangler says:


      Thanks for the question. I wish I had the silver bullet answer, but I don’t. Hydrostatic pressure is possible, for the reasons you listed, but having it start only after this length of time seems odd without additional factors. You don’t talk about a vapor retarder directly under the slab. Did they use one? If not, you may have actually been lucky nothing has happened prior to this. Depending on various factors, as construction and population have started to increase, there can be additional changes to the soil. New landscape on your property, changes in drainage in the subdivision, additional subdivisions constructed nearby, etc. All of these can have an impact. You may need to call out a geotechnical engineer to help you with the situation. Good luck.

  2. kathy kennett says:

    Hi Jason, I have a retail flooring store & last year we installed luxury vinyl plank (click) on concrete slab that tested in the normal range for moisture. The planks cupped & pulled apart, so we tested concrete again and was very high in moisture. We removed the planks, let the concrete dry out, tested it again & it was normal. Installed another click plank & 6 months later had the same issue. Had the rep from the manufacturer look at it & he noticed there were no gutters & the downspouts drained straight down into the stone around the slab. He suggested they get the water draining away from the home. Could this failed flooring issue be eliminated by better drainage or should I look into a moisture mitigation product before attempting a third installation? Thanks, Kathy

  3. Catherine in Florida says:

    Hi Jason,

    I have a 22 yr old monolithic slab home in central Florida. I replaced my carpet with porcelain tile that had to be removed 6 months after being installed due to an installation issue. When the tile was removed about 1/3 of the concrete flooring in that room had a sheen of standing water which promptly evaporated. We have installed French drains, which are draining well, along the perimeter of the house and sealed the side of the slab down to the footer over pour. However even after running a dehumidifier and leaving the slab exposed for the past 6 months the rh moisture reading in the problem area remains at 99%. We have brought in 3 different plumbers and slab leak specialists who assure us that there is not a plumbing problem. There is no roof problem and the walls show no excess moisture readings. We brought in a foundation specialist who has suggested that injection of PolyRenewal under the slab in that room might solve the moisture issue. Any input you could offer would be greatly appreciated!

    • Jason Spangler says:


      Thanks for the questions and sorry you are having issues. My guess would be, given the evaluations you have had from various professionals, is that you don’t have an intact vapor retarder under the slab. This would allow moisture vapor from the soil to infiltrate into the slab. The most common way to deal with this is to put some type of moisture mitigation product on the surface of the concrete to lessen the amount of moisture that can actually interact with the floor finish. If you are going back with porcelain, you might also investigate uncoupling membrane.

  4. Carolyn says:

    HiJason, I own a townhouse built in the early 80’s on a slab above grade, no basement. We are in Annapolis, and our front is a small but steep hill, and our yard backs up to a fairly large hill in the back yard. Recently, we’ve noticed our dining room (center interior of 1st floor) rug being damp one day, then wet a day or two later in one particular spot close to the Kitchen fridge and dishwasher. Monitored both appliances and no leaks. Yesterday we thought we had no additional dampness until last evening when I noticed another small damp spot about 2-3 feet away from the spot first identified. It appears water is seeping through the cracks between my relatively new luxury vinyl plank floor boards. What could be causing this and what do I do next, call a specialist or my insurance company? Thanks, in advance, for your advice!

    • Jason Spangler says:


      Thanks for the questions. If you had the floor installed by a professional, I would start there and see if they can determine the problem. Did they test the moisture condition of the concrete prior to installation? You may also want to rule out any plumbing leaks by calling in a leak detection specialists. If no leaks in the plumbing then I would probably look to a geotechnical engineer. Good luck.

  5. It was interesting when you explained that concrete may get increased relative humidity if it’s left in contact with water for a long time. My husband and I are interested in having a small custom home built so we can have a comfortable yet minimal place to retire. thanks or teaching me why basement waterproofing should be an important part of the home-building process!

  6. Carol Wheeler says:

    Our 4 metre high stone retaining wall collapsed in December during an orange warning storm and unusually high rainfall on the weekend and for a week before. The wall had drainage holes every 1.5 metres. The insurance expert asked to do a visit by video and has said that the collapse is due to hydrostatic pressure due to lack of drainage. The wall is probably 150 years old and we had no previous problems. Is this really a diagnosis that can be made on a 5 minute video call and wouldn’t we have had some warning signs?
    Thanks, Carol based in South West France!

    • Jason Spangler says:


      Thanks for the question. In my opinion, nothing is ever impossible, but a five minute video call for a proper diagnosis of this nature is very improbable. I believe I would ask for a second opinion or find someone on my own that would give me a more thorough evaluation to potentially dispute the “experts” claim. Good luck.

  7. Jennifer Watkins says:

    Can hydrostatic pressure happen to a house with a basement on top of a hill. From what I am leaning the issue normally happens to homes below other homes or on a hillside. But if you are at the top of a hill wouldn’t the water run down. My parents basement just flooded and the restoration people are saying hydrostatic pressure. I am just not understanding how that is possible on top of a hill?

    • Jason Spangler says:


      Thanks for the question. Anytime you have a building elevation that has the potential for water to reach a level higher on the outside than on the inside (basements) hydrostatic pressure is possible. The backfilled soil is moist and this can cause a pressure differential between the moisture against the wall and the moisture below the floor. Now, I’m not saying specifically that is what your parents’ issue is, but it is possible.

  8. Kris Bridgewater says:

    Hello. I have a basement floor that water comes up through where they are cracks. Basement had a drainage tile put in around the outer walls. Holes drill into the blocks and sump system installed. My question is. How is water still able to come up from the floor if the pressure was taken off by the tile and sump.
    The floor was poured right on the mud. No nothing between the two.
    Way to many years of water coming up that way is still easier for it do so? Then go through the mud to the tile?

  9. Gisela Greenlee says:

    I have a question regarding how long it might take excess moisture to drain from underneath a concrete foundation with high clay content soil after the situation causing the excess moisture has been remedied (installing french drains or extending downspouts to stop moisture from collecting or pooling near the foundation. Any ideas on what I can expect?

    • Jason Spangler says:


      Thanks for the question. Unfortunately, this is a million dollar question. What I can state, with reasonable certainty is that is probably won’t be as fast as you would like. Sorry I can be more definitive. Good luck.


  10. Lynn White says:

    New Years night I discovered wet carpet in my master bath, but no water was coming from the toilet, sinks, shower or tub. The net day a friend helped me search for a source and we found none. The carpet was pulled up to discover wet concrete in the center of the room. I arranged for the plumber who installed plumbing when our home was built 20 years ago to come check for a leak and the pressure gauge test showed no leak. Now what do I do? I welcome your guidance.

    • Jason Spangler says:


      Thanks for the questions. This is a very puzzling issue, especially if it is something never noticed prior. Having a knowledgeable building inspector come out and evaluate the situation and potentially rule out temperature and humidity variations in the bathroom air vs. temperature variations on the concrete surface that may be causing condensation may be a good place to start. If that shows nothing abnormal then you may need to have an engineer come out and do concrete core samples, looking more closely at the vapor retarder (if there is one in the area) and the soil. Good luck.

  11. kind of the same problem well 6 feet from house which is located into a high hillside thw well is 180 feet deep and the water level is 8 feet from the top. Trying to figure if the moisture is hydrostatic or from the hillside, Any help appricated.

    • Jason Spangler says:


      Thanks for the question. Many times the hillside (higher elevation vs concrete slab) can cause the hydrostatic pressure, it’s not an either-or situation. I hope this helps.


  12. Dave says:

    Hi Jason,
    I have a well that hasn’t worked well(lack of pressure) for the past 20 years or so. I recently had a new pump put in giving us plenty of water pressure.
    Around that time we had some water leak into our basement. The well is 8-10 feet from our house. Is it a possiblity that replacing the pump thereby adding greatly to our water pressure could have increased the hydrostatic pressure around our basement causing the leak?
    I might add we did have a leak at our city water faucet at the same location so I’m leaning strong towards this cause but I am still curious about the well.

    • Jason Spangler says:


      Thanks for the question. Wish I could be more help, but I have never heard of an issue like you describe causing increased hydrostatic pressure. Good luck.

  13. Tib Morrison says:

    Hello- we had a water event in our basement (1930’s farmhouse) that resulted in 7,500 gallons (approx. 65,000 pounds) of standing water in a 15 x 20 foot rock wall foundation basement for 7 days. Our insurance company is saying that the damage to our foundation (significant shift) is a result of wear and tear over time NOT the actual water event. We have explained that the while the walls were not 100% plum before the event they are now significantly different (house unlivable) with a tilt to the entire house which we assume is a result of the weight/pressure of that much water.
    Do you have any opinion if our assumption could be true or if that much water would not necessarily effect foundation walls?

    • Jason Spangler says:


      Thanks for the question. I would say with that much water anything is possible. At this point, it looks like it may be up to you to prove it. I would look up structural and/or geotechnical engineers and see about having them evaluate. I would think that they could do calculations. Part of the issue though, in my opinion, may be proving how much of the problem now is directly related to the water, unless you have some tangible proof of how bad it was prior. Good luck.


  14. Ashley Maxwell says:

    Thanks for your comment about hydro testing should deal with all sources of water. I also like how you said that those who work in this field should have a lot of knowledge and expertise. My husband and I are looking into hydro testing; thanks for your post.

  15. Kathy gilbert says:

    I have a 110 year old brick building made into apartments . The main floor apartments are on concrete floors and have hot water heating pipes passing thru. One of these pipes has started to rise above the concrete like a tent top. Or inverted v what would cause this.
    I am in northwester Ontario in canada

    • Jason Spangler says:


      Thank you for the comment, but unfortunately, this isn’t something I have experience in. I would contact someone who specializes in hydronics to evaluate the situation. Good luck.

  16. Carole Cipriano says:

    Hello Jason,
    I am so happy I’ve found your website! Almost 30 years ago I hired a company (they are now out of business) to install a French drain in my basement. I never really had any water other than when a power outage for 12 hours disabled my sump pump (I was away overnight so had no knowledge & no backup battery) but I installed the French drain shortly afterwards for “peace of mind”.
    30 years hence one of my basement walls exhibited large cracks going in various directions and I had a cracked sewer pipe from where a portion of the wall was collapsing on it. I hired a structural engineer in conjunction with a “foundation expert” and the wall was repaired using rebar inserted in the walls to stabilize them. It was determined by the “foundaion expert” that when the French drain was installed the wall footings were compromised, thus the wall failure. They removed the French drain, replaced the stones used for drainage with appropriate stones and then Dry-Locked the wall. Now I am getting a considerable amount of seeping at the cove and water coming up through the floor. It runs the entire length of the “new” wall. I vacuum up water in a 3’X30’ area at least twice daily.
    My contractor is stymied and is blaming everything and everyone he can think of. My house is a twin home and I coerced my neighbor into replacing all her gutters. I called the plumber who repaired/replaced the small piece of sewer pipe to be sure he back-filled properly after excavating that small section (he swears he did).
    Here is the rub: my foundation expert says that if I install a French drain along this wall, the WALL WILL FAIL !
    Can you render any opinion or suggestion here.
    Thank you so much.

    • Jason Spangler says:


      Thanks for the comment. It sounds like you had none of these issues when you had a French drain, but the French drains weren’t installed properly so the wall failed. Now that the wall is fixed, why not install the French drains correctly? I hate to be so simple in my response, but French drains have been used for years with great success and I have a hard time believing they would be used if it was at the expense of the structural integrity of walls. I would consult additional drainage and foundation experts in your area. I hope this helps.


  17. Wendell davis says:

    I have a cellar basement also known as a “Michigan” basement. 3-4′ inside the foundation a cinder block wall was built on a 4″ slab. this space was back filled with soil and capped with concrete. water enters at the base of the interior wall where it meets the slab. I am putting in a drainage pipe to a sump pump. the question I have is – by digging a trench below the interior wall will any water behind the block wall find its way beneath and into the drainage pipe alleviating hydrostatic pressure?

    • Jason Spangler says:


      Thanks for the comment. You will find that many people have installed some type of French drainage system, or hybrid, in this situation, with success. Good luck.

  18. Maria says:

    Hello Jason, we just bought a house (2 weeks ago) and on the 2nd day we noticed a little puddle of water, I thought someone had spilled some water, I cleaned it up and half an hour later it was there again. We have had 3 Plumbers come out and stated that there is no leak, we do have a pool and had 2 Leak Inspectors come and they stated our pool is not leaking. We don’t know who else to turn to, the puddles keep coming up, small but consistent. The puddles are in our family room- room has tiles. Thank You- Maria

    • Jason Spangler says:


      Thanks for the comment. This is a tough one. You don’t state the flooring type, but there are organizations of flooring inspectors that specialize in various types of flooring. These inspectors, based on their experience, may be able to give some suggestions, after evaluating the situation. Another option would be to have a geotechnical engineer come out and take a look. Good luck.

  19. Nat Bosk says:

    We have a three year old home in Southwest Fl where a water intrusion specialist has determined that all along one wall hydrostatic pressure has forced water to come penetrate between the wall slab connection and possibly through the slab. The builder provides a ten year warranty but has indicated this is not covered. We have a engineered wood floor that is glued down. Portions of the floor adjacent to the wall are now damaged. What steps would you recommend to correct the situation before we replace the damaged portion of the floor.
    Thank you,

    • Jason Spangler says:


      Thanks for the question. Probably the first person to ask, in my opinion, is the water intrusion specialist. What are his realistic recommendations to fix the problem? i.e. French drain, additional foundation sealing. Once this has been determined and addressed, work with a reputable flooring installer to come up with the appropriate reinstallation remedy.



  20. Megan says:

    Hello Jason,
    I was wondering if there was any procedure for measuring hydrostatic pressure? Specifically, I was wondering if there was a way to measure the hydrostatic pressure on a floor in PSI (or equivalent that I can convert to).
    Would love your input.

    • Jason Spangler says:


      Thanks for the comment. Unfortunately, I am not aware of an instrument that records this information.



  21. Kathy Rice says:

    Hi Jason

    We moved into a new home in June of last year. We immediately noticed hi RH 80%+ in the crawl space. We found a leak in a drain line and fixed it, but RH didn’t drop off until winter. Then we found mold in February. We had it remediated now the RH is back above 90 most times. The builder hired a structural inspector. Who has done some testing and found that downspout and runoff water are coming in the crawl space. The builder said at first that hydrostatic pressure was pushing the water in under the footer. There is a sealer on the outside of the block and no dampness on them. The builder used forma drain for the footer, with no escape for water from inside. He did not tie the inside to the outside drain either. We have dug out several holes beside the footer and looks like some gravel below the footer, but builder is swearing hydro pressure. Would you have any advice for us. We installed a sump pump and it comes in several hundred gallon at a time. We would like to stop it from coming in. Any advice?

    • Jason Spangler says:


      Sorry to hear about your issues. The best advice I can give you would be to hire a geotechnical engineer and see if they can be of assistance. Some in this field are also construction orientated and may be able to identify the problem and offer solutions. I hope this helps.



  22. Joanne Aliber says:

    I have a 3 story townhouse built in 1985. It is outside Boston. The basement is unfinihsed, below grade and opens to a common hallway corridor that is shared by the other 9 units, all of which are connected in the row.
    The Association has a history of water problems – poor gutter drainage, roof leaks, bad storm drain construction, clogged drywells. The foundation outside the basement of my unit has cracks, which have allowed water to enter into the corridor and travel under the walls and doorway into the basement. This problem went on for years until finally I filed a legal complaint against the Association; two years ago they brought in CrackX to plug the leak holes. I had to mold remediate the basement, reseal the floor and essentially I thought this was done. Then, just a few weeks ago, the water started again. It started coming across the hallway corridor and under the wall. CrackX came again and re-treated the work they had done 2 years ago as it was under warranty. But even since, without any heavy rains this week, there are puddles again in the middle of the basement floor.
    The association property manager is inexperienced and blames everything on rain. I am convinced this is all from hydrostatic pressure this is due to cracks in the exterior foundation. (I went through this once before in another house). I am pretty convinced the only solution would be in interior basement perimeter drain, but I don’t think that cost should fall on me. Is there a way to image the foundation to find out where the water is coming in and building up from? I fear the Association will again deny any responsibility, as they did for years, and then I would have to again file a legal complaint, and essentially when the house is sold, potentially not realize full market value due to the ongoing water problem.
    Can you recommend any Massachusetts firms to help me evaluate this problem?

    • Jason Spangler says:


      Thanks for the email. Unfortunately, I have no immediate knowledge of someone in your area that could help. I would recommend starting with a Geotechnical Engineer (Google can probably find a few) and you may also need to get a Structural Engineer involved. I hope this helps.



  23. Renaud Martowski says:

    It’s spring thaw season. I have a house with a crawl space in a rural area(country).
    I dug to 8 inch holes about with a three foot depth. There was water in the bottom of the hole.
    With the snow melting and rain, the water level has risen to the top of the hole.
    Will hydrostatic pressure force the water out of the hole and into my crawl space ?
    I am afraid that the water will soften the sandy earth in my crawl space and the cement pads which hold the beans and joists, will sink and force the house to collapse.
    Any info relevant to my situation would be appreciated.


    Renaud Martowski

    • Jason Spangler says:

      Renaud, thanks for the question. I would consult an engineer that would have specific knowledge of your area, including soil types. They should be able to help in this situation.

  24. Kim says:

    Thank you for this informative article. I am currently having trouble finding home owner’s insurance that will cover hydrostatic pressure cracks; however, I am trying to examine the potential risks for one. It is my understanding that there was a repaired crack before I ever bought my house (could not be inspected because there is drywall up in my basement). It was supposedly fixed and then the basement was professionally waterproofed with a lifetime transferrable warranty. I know it’s impossible to know for sure what the future will hold, but I didn’t know if you could provide any insight as to whether it is worth paying considerably more of a premium to have that coverage.

    Thank you!

    • Jason Spangler says:


      Unfortunately, this is a question that could only be answered by a crystal ball. I guess I would have to evaluate, personally, by what the damage could be if there was a problem (how much would it cost to fix) and then how long would it take me to save that much if I took the premium difference between an insurance with that rider and one without.

  25. Ty says:

    Wondering if you could propose a hypothesis. I have a below grade slab in 1984 built colonial. Never, ever had standing water on floor or any type of water. There is a sump basin in corner that rises and falls due to melting snow, etc., never had a need to pump. Did see some efflorescence here and there at junction of walls and floor, but again no actual water. I refinished part of the basement and put vinyl plank down over the concrete. The concrete had some old paint from previous owner and I scraped all loose and flaking prior to laying floor. The specs on floor said NOT to put down a vapor barrier or 6 mil sheet etc. Install was done in summer and a few months ago, I noticed water coming through the gaps/cracks in the vinyl floor in different areas so I know that the water vapor that must of evaporated in the past is now getting trapped. I’m planning on pulling up the vinyl, letting it dry an then reinstall but I need to address the water. Some ideas are to concrete sand the paint, etch, then use something like Xypex, RedGuard, HydroBan, etc., then put DMX Airflow before installing the vinyl. Main question is whether the water getting trapped is due to hydrostatic pressure or weeping. Not sure I understand the difference and some of the waterproofing products are specific as to yes or no for hydrostatic pressure.
    Thanks for you time.

  26. Tom Walentowski says:

    My basement will flood from under the ground when the creek which is located 150 feet from my house is full of water. The last time my basement flooded I had 5 sump pumps running and the the basement still ended up with 20 inches of water in it. I have had several people out who have not been able to help I purchased a system from one company that put additional sump pumps and crocks in but they have not help when we get the worst case situation. I am told that the bedrock in my area is high and the creek is somehow feeding the bedrock and when the creek is full the water backs up into my basement. apparently my basement floor is only a foot or two above the bedrock. I need to find someone who will know the type of situation I am in who can give me some answers. All I hear from people is the same comment ever time “I have never seen anything like this before”. any advice would be appreciated.

    • Jason Spangler says:


      Thanks for the question. I hate to be a broken record, but you have me stumped on this one. Reaching for straws, I could only question whether setting up a perimeter drainage system around the house, deep enough that it would intercept the water prior to infiltration wouldn’t work? I would have some type of soil engineer evaluate and give recommendations.



  27. Andrew Larson says:

    Hi Jason,

    Thank-you for the informative posting. I have a question on a hydrostatic diagnosis and trench/dry-well fix.

    My scenario: (Pac. NW/Seattle) below grade concrete basement (circa 1941) – clean-looking foundation floor/walls when demo’d. The house sits at a high spot, with gentle grade away from all sides, esp. the SW area. A great finished basement was constructed in the space.

    Over this current very rainy fall and winter, notice the SW corner only (spot that gets the most weather here) with some significant seeping in at slab/walls intersection floor level. Causes carpet and floor-molding to be pulled. Isolated (luckily) to that corner.

    That location in the SW corner is adjacent to and below a window well (window down from the corner of the house by 24″ or so) that had a bad drain pipe out of it routed towards the backyard, that would fill-in with standing water, during heavy rain periods.

    Conclusion was that standing water in window well was very possibly contributing to too much water presence in and around that SW corner area overall, possibly creating h-static pressure down below. Further evidence on too much water was highlighted by water backing INTO that window-well via poorly performing drain pipe (from the yard), vs. evacuating out (which was the original design, I’m sure) – and that it needed to be fixed.

    (I at one point shop-vac’d 100 gal. out of it.. it kept back-filling up from that drain pipe that terminated somewhere in the backyard, each time I’d fill the 20-gal. vac up ..more water would run in from that drain-pipe.)

    After several months’ inspection and conjecture, best course and fix seemed to be trenching a properly sloped drain-pipe (perf’d pipe w/ gravel etc.) from that SW window well to a significant 8′ + deep dry well 18′ – 20′ away from the house. Excellent local co. did the work, and that window well has performed perfectly in heavy rains since (no standing water at all).

    However, still seeing some ~ reduced but some, continued seeping in that basement SW corner (which is exposed still) after the recent heavy rains.

    Is it possible that down that far (7′ – 8′) the hydrostatic water effect is still present to some degree, and will exhibit residual presence/seepage in through that corner/slab intersection for awhile, albeit at reducing levels, until the new trench/dry well (even though it’s deep, it is still above the slab level of the basement) has had time to make its full impact and effect?

    Or, should that type of solution, if it is the correct answer, have an immediate all-encompassing effect and eliminate further seepage instantly?

    Thank-you for your thoughts and reading this,

  28. Larry Hall says:

    I own a home in Florida, built on a slab in 1981. I bought the house 4 years ago. About one month ago I notice a small puddle of water in my family room sitting in the grout line of the tile floor. I dried it up and the next day it came back. It does not grow; it spreads about 2 inches along the grout line and stops. It is as if the surface tension does not let it flow onto the tile, or that there is not enough pressure to make it run.

    A leak professional told me that I had no leak after doing his tests. He thought it was the slab sweating. He pointed out the efflorescence on several other grout lines, telling me it was an indicator that the sweating had actually been going on for a while.

    This led me to your posts on the Wagner Meters website. My question to you is: what type of trade professional do I contact to help me solve this problem? I do not know where to start.

    Thanks for any help you can give me. And Merry Christmas.

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