Low Water Pressure in Home (Diagnosing Problems, Solutions)

September 9, 2009 | by Fred (email) |

Low water pressure is a real downer. There’s nothing quite like looking forward to a hot shower and finding out that instead of 20 minutes of relaxation, you’ll spend 10 miserable minutes trying to squeeze yourself up against the wall under a dribbling shower head (tell us you haven’t been there at some point!)

Fortunately, low water pressure can be boiled down (no pun intended) to a few causes that are relatively easy to diagnose. You may have to call in a professional plumber to deal with some of these and even to pinpoint a diagnosis, but rest assured that they are repairable with a little perseverance.

Note that this article deals primarily with pressure issues associated with water connected to a public water supply.  While the same concepts also apply to well systems, there are more issues with well systems that can create pressure problems that I don’t cover here.

Reasons for Low Water Pressure

water-pressureTo identify the cause (and solution) for low water pressure, determine which type of problem best describes your situation.

Low Water Pressure At a Faucet or Shower Head

If the low water pressure is isloated to a single faucet or shower head, the most likely culprit is a clogged filter or aerator screen in the faucet itself. This is particularly common in shower heads, almost all of which are designed to be disassembled and cleaned periodically.  This can happen immediately after you have new plumbing installed too, since bits of solder or other contaminates may be stuck behind the screen from when the plumber (or you) soldered the pipes together in the first place.  This video on fixing shower water pressure is a good place to start if this is your issue.

Other causes for low water pressure in this scenario that are less likely:

  • The valve controlling that branch of the plumbing is partially closed, or potentially stuck or clogged.  You can replace the valve to solve this problem.
  • There’s something constricting the flow of water in the plumbing somewhere else (this will likely require a professional to snake the lines).
  • There’s a bad crimp in the piping somewhere… Uncommon but it can happen, especially on <= 1/4 inch pipe runs to things like refrigerators.
  • The plumbing is too small for the branch (e.g., a 1/4 run is used where a 1/2″ run is appropriate).

Lower Water Pressure on the Second Floor

Low water pressure on the second floor in almost always caused by a general lack of water pressure in the whole house that is exacerbated on the second floor.  Or, it can also be isolated to the second floor because there is a problem only with the second floor plumbing.  Here’s some things to check:

  • Ask a neighbor if their pressure is low.  If a neighbor has low water pressure too, the issue is probably with the municipality.  You have a few options in this case: (1) contact the county/city and get them to fix it; (2) install a pressure booster system on the main line (requires a professional plumber);  (3) run a larger main pipe from the water main to the house (and larger plumbing throughout … very expensive solution but it can work… this would be a last resort).
  • Check the first floor water pressure.  Is it low?  If so, the problem is systematic to the whole house.  Either there’s a major leak, or the water flow is being blocked.  Pressure regulators are known to clog eventually, and can produce this effect throughout the whole house.  If you have a situation where the water pressure briefly “spikes” when you turn on the water, and then goes to a dribble or much less, this is almost certainly a water flow constriction somewhere in the pipes or a valve.  If there is no spike in pressure, the problem is either a leak or low pressure from the public supply.

Low Pressure When Other Faucets Are On

If the pressure is low only when other faucets are on, there’s three likely culprits:

  • A blockage in the pipes or a valve.  You will likely notice a “spike” in water pressure when the first faucet is turned on, quickly diminishing after that.
  • A leak.  Find it and replace the pipe / patch the hole.
  • Insufficient flow to the house.  Install a larger water main to correct this, or contact the public water supplier and ask them to check the system.

Low Water Pressure in a Neighborhood

If the entire neighborhood suffers from low water pressure, one of two things are true:

  1. The main water supply to the neighborhood is insufficient.
  2. There’s a systematic problem with the neighborhood’s plumbing.  For instance, some neighborhoods built in the late 80s have Polybutelyne plumbing, which can eventually crack or explode.  There could be multiple homes with leaks, thus lowering the water pressure for the whole neighborhood.

Small drops in pressure are normal in neighborhoods, particularly at high water use times (6-9am, 4-7pm).  You may have trouble getting the county/city to correct the problem if the issues are intermittant.  If the problem is bad enough, consider asking the HOA to address it with the county, or contact an attorney and discuss your options.

When to Contact a Plumbing Contractor

At the end of the day, if you’ve exhausted all other options, it’s time to get a plumbing contractor.  Many times they’ll be able to pinpoint a problem you hadn’t suspected was an issue.  Look for a reputable contractor, if possible one who has experience with homes in your neighborhood.  There may have been a systematic problem with the plumbing in all of the houses around you, and they’ll be the best qualified to address the situation.

(photo credit: Steven de Polo)

13 Responses
  1. Nicole says:

    Great post, Fred! We just went through this with a kitchen faucet that we’ve been battling for nearly TWO YEARS! We’ve replaced all kinds of little parts on it, only to have it be a very temporary fix. Finally, a rubber washer and new spring have done the trick. The difference is incredible.

    The faucet STILL has issues but since it’s on its way out soon, not going to drive myself any crazier over it. For now, we have hot water AND strong pressure in the kitchen again.

  2. Fred says:

    Nicole, thanks for the kind words. Low water pressure is a real downer. We just faced it in our rental property. The solution to our problem is coming up in a future post.

  3. Curtis says:

    We have well water and within hte last two weeks our water pressure in any faucet has come to a near trickle. Even the hot water. Do you have any suggestions as to what this might be??? We have had plenty of rain, so our well should have enough ground water replenished.

  4. Fred says:

    Curtis, Could be a lot of things… dry well, faulty pump, some obstruction in the line…

    • Lucy says:

      Hello. I was informed that our neighborhood has low water pressure. The homes were all built within the last 4 years. What could be the cause?

  5. Curtis says:

    Thanks, I don’t think it is a dry well, the pump is working so I guess we need to try to flush out the lines.
    We bought a new washmachine and the water lines where disconnected for one or two days, would it be possible that air has entered and is now blocking the flow of water?
    Also have you ever heard about a well booster system. Is this a gymick or really worth the money?

  6. Grace says:

    Thanks for the tips! We have a 2nd floor rental unit with low pressure with shower head and faucet… Will try cleaning out shower head and faucet. Also I think it takes long time for hot water to come up. What are some possible causes?

  7. Luis says:

    Fred: I have an issue with a low pressure water in the second level shower after I connected the water lines to the basement for a new full bathroom. The connections was made to the line in specific. It’s that creating the low pressure of water or could be air trapped in the water line. Thanks in advance.

  8. Rich says:

    God I love the Internet. A 9 year old post reminds me to check the 2nd floor faucet filters after shutting off the main. Huge problem solved in 2 minutes. Thank you lol

  9. Anne says:

    Just 1 2nd floor faucet developed low pressure starting a couple years ago. We had an expansion tank added to the hot water heater and a sump pump that is water driven if the electricity goes out. The hot water faucet to the bathtub ( used 1-2 times/week) developed slow flow down about 75% but cold faucet was fine. Now even the cold faucet is a trickle. All other faucets, shower on 2nd floor are fine. What’s the likeliest problem? There is no aerator on the faucet- that would be too easy! Anne

  10. Fred Clark says:

    Low pressure from community water dept is not going to change for years until a new higher elevation storage tank is completed. We are thinking of a system of unpressurized storage tank with inlet shut off as per toilet tank, feeding high pressure pump feeding two pressure tanks at 35psi and feeding whole house. Maybe even water filters before the storage tank. Would have drains on holding tank, pump and hot water tank. any thoughts?

  11. Michael says:

    Just replaced a well pressure tank,(all new fittings) a pressure switch (40/60) a pressure gauge, new filters in house. We have good pressure in all downstairs, we have only a trickle in the shower and tub. Any suggestions..??

  12. linda mueller says:

    so simple you fixed it for me, clogged filter in the faucet, so awesome when this 69 yr old woman can fix it herself
    thank you

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