Building plumbing system installation, inspection, troubleshooting & repair:
These plumbing repair articles answer nearly all questions about diagnosing and repairing building plumbing systems, including water supply and drain piping, vent piping, gas and oil piping in buildings, plumbing fixtures, water heaters, water pumps, water pressure, water softeners, water testing, water treatment equipment, water wells, and septic systems.
We also explain oil tanks, water tanks as well as other building plumbing system inspection or defect topics.
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This InspectAPedia page provides links to both article indexes by major plumbing topic and links to in-depth articles on inspecting, testing, and repairing problems with above ground and buried oil tanks, septic system design, inspection, testing, water supply and drain waste vent piping, wells, water supply pumps, water tanks, water testing and water treatment. New York State License # 16000005303 (inception to 2008)
Below on this page we describe the contents of key plumbing system articles and indexes organized by major plumbing system topics.
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For a complete index to articles about plumbing systems, controls, equipment, fixtures, pipes, etc. see ARTICLE INDEX to PLUMBING SYSTEMS
Watch out: while the 2015 IPC is the most-recent version of the International Plumbing Code, while the 2018 IPC is under development. To understand which generation of the model building code or plumbing code applies to your specific project you will need to check with your local building official. For example many jurisdictions are on the 2012 IPC or still older versions.
The following basic water supply information is adapted with permission from Carson Dunlop AssociatesHome Reference Book.
Also see WATER HEATER PIPING - how are individual or mulitiple water heaters hooked-up: how are water heater pipes and heaters cascaded, ganged, in series, in parallell
If your water supply is from a municipal supply and there are pressure or flow problems, see MUNICIPAL WATER PRESSURE DIAGNOSIS. Excerpts are below.
Typically, the water mains in residential areas are four inches to 12 inches in diameter, and run several feet below the street level. Smaller pipes, usually 1/2 inch or 3/4 inch diameter, run from city mains into buildings. The water is normally supplied at a pressure of 40 to 70 psi (pounds per square inch).
The 1/2 inch or 3/4 inch diameter service piping carries the water from the street mains to the house. Some early service pipes were 3/8 inch diameter. Most or all of this cannot be seen.
Lead piping was used between the street main and the house up until the 1950s. A good deal of lead supply line is still in use, and the health authorities indicate that as long as it is used regularly, there is no difficulty with it. If the water has not been run for some time, many recommend that the water be flowed for several minutes before using it. The life expectancy of lead piping is indefinite. See
Copper piping has been used extensively since the early 1950s for supply lines from the city main to the house. From 1950 to 1970, 1/2-inch diameter piping was used commonly. After 1970, 3/4-inch diameter copper service piping has been common. The life expectancy of
copper piping is dependent on water conditions. In many areas, its life expectancy is indefinite. In harsh water or soil conditions, it may fail within 20 years.
Galvanized steel is not commonly used as a service pipe, although galvanized steel fittings may be found at the point of entry into the house. Where galvanized service piping is used, it is typically at least 1 1/4-inch diameter. The word galvanized means zinc-coated. The coating helps prevent the steel from rusting.
Plastic water service piping may be polybutylene (PB), polyethylene (PE), cross-linked polyethylene (PEX), polyvinyl chloride (PVC) or chlorinated polyvinyl chloride (CPVC). Most plastic piping is buried at least 18 inches deep. Exposed piping may be subject to mechanical damage and deterioration from sunlight.
Since the supply line from the street cannot be seen, no comment is offered during a home inspection. If there is a leak, it may go undetected for some time. In some cases, water can be heard running outside the basement wall. Water accumulating in the basement or a wet spot on the lawn is often the first indication. Leaks may be caused by building settlement, excavation, poor connections, faulty valves or a flaw in the pipe itself.
The underground water service line from the property line to the house is owned by the homeowner. Beyond the property line, the pipe is the responsibility of the city. A leak in the pipe requires excavation, and it is often difficult to know whether the leak is on the city’s or the homeowner’s side.
The city is usually contacted and they excavate their section of the pipe, correcting the problem if they discover it. If no problem is found, the homeowner is left to correct the problem on his or her own. In some cases, the homeowner must pay for the city’s work if the city pipe is not at fault. Some municipalities use sophisticated leak detection equipment.
Poor water pressure in the house may be the result of a partially closed or obstructed valve in the street. It may also be because of blockage, such as a stone or other foreign body in the pipe. New piping may be crimped during installation or become pinched under a rock during back-filling operations. This can also cause low water pressure.
City water mains may be undersized or deteriorated in older neighborhoods. Some cities have poor pumping and/or distribution systems. In these cases, low water pressure problems are usually experienced at every home in the neighborhood. The solution is to petition the city to improve its system.
In most new housing, the supply pipe from the street to the house is 3/4-inch diameter. In older houses, the piping was as small as 3/8-inch. Modern life styles and additional plumbing fixtures usually require a larger line, capable of providing more pressure and volume. Replacing this pipe is an expensive and disruptive job. It is often deferred as long as possible.
In some older semi-detached (attached) and row houses, a single supply line would run under a front lawn, and then split to feed two houses. This often yields unsatisfactory water pressure for both houses and is often replaced with two larger, separate lines.
Where municipal water pressure is above 80 psi, [perhaps even above 70 psi] a regulator Needed should be provided to reduce the in-house pressure to prevent leaks at fixtures, stress on appliance hoses and possible broken pipe joints.
Details are at WATER PRESSURE REDUCER / REGULATOR.
It is unusual, although not impossible, for the service pipe to be too close to the surface, and to freeze during very cold weather. Many service pipes extend above grade just before they enter the house.
See WINTERIZE A BUILDING.
Up until World War II, most of the service pipes in built-up areas were lead. While these generally provide good service, they are small in diameter and may have to be replaced. Also, lead is relatively soft, and if building settlement occurs, there is a chance of leakage or crimping the pipe. Leaks can also occur at connections as a result of long-term deterioration.
Many of the old lead service lines were connected to a galvanized nipple – a short piece of steel
pipe that was often in contact with the soil. This pipe rusts on the outside and inside, and may be close to the end of its life. It is often wise to replace this as a precautionary measure. Galvanized steel service pipes typically last roughly 40 years.
See details at LEAD PIPES in BUILDINGS.
- Adapted from Carson Dunlop AssociatesHome Reference Book.
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(June 4, 2012) Sumii said:
Thank you for your information regarding faucet without water pressure. I didn't have to call professional. I fix it myself.
Thank you for the nice note Sumil. We work hard to make information at InspectAPedia accurate and helpful so your feedback is very nice to receive. We also welcome questions if you find our articles unclear or missing something.
(Oct 13, 2011) Sally Slick said:
I moved into a rental house 3 months ago... I have noticed a sickly sweet odor that permeates the house... that is, does not appear to come from a specific spot, but is more noticeable around the center of the house where the shower, toilet, sinks, washing machine and dish washer are. It is much stronger after I use a lot of water with showering, doing laundry etc.
My landlord (a management company) is being nice, but want me to cover the odor via various means rather than finding what the cause it. It seems to me that this is sewer gas. The house was empty for quite a long time apparently before the owner bought it in a short sale. I would very much appreciate your thoughts on this. Thanks...
Sally, a sickly sweet odor - can be too many things, I'm just not sure enough to guess based on odor description alone what the problem might be. But the fact that you observe the odor more strongly after using plumbing fixtures suggests there may be a drain or vent clog problem.
Because sewer gases are potentially dangerous I don't think that just covering up the odor is a reasonable approach.
I suggest trying to track the odor to its source by building location and time of day, plumbing fixture usage, etc.
Start by taking a look at the article titled ODORS & SMELLS DIAGNOSIS & CURE and the plumbing and sewer gas odors listed there - (article links are at page left).
(Nov 8, 2011) jeannette said:
when i turn the water on, it has good steady pressure until the pump turns on. when the pump cuts on, it starts sounding like a coffee pot making coffee(sounds stupid, but, the best way to describe). air starts comming out of the line along with water. any clue whats going on?
please see our diagnostic suggestions for air discharge at plumbing fixtures - it's found at AIR DISCHARGE at FAUCETS, FIXTURES (article link at page left).
(Apr 23, 2012) Cliff said:
we live in the country. Gimli. Our breaker with the pressure pump and delhi does not shut of. It just keeps running. We now have switched the breaker off. We therefore would like to know what could possibly be the problem. Is it the switch?? or loss of pressure in tank? or a water problem.
(May 29, 2012) Anonymous said:
plumber installed a new toto toilet urine smell coming out of toilet sewer gas smell coming out of pipes under bathroom sink plumber put in new downward vent didn't help either smell what needs to be done?
Anon: diagnosing toilet urine and sewer gas smells:
At ODORS GASES SMELLS, DIAGNOSIS & CURE (article links at page left) we provide several diagnostic guides to tracking down and curing odors at their source. For the case you describe, and with no other information, I'd start by
1. a thorough deodorizing cleaning of all surfaces around the toilet to eliminate any confusion, then
2. there should be no odors coming out of pipes below a sink - as those pipes should not have any leaks whatsoever, so check or re-make any questionable drain, trap, or similar connections there;
3. make sure you've accurately traced the odor to its source - it could be a bad wax ring seal at the toilet, for example.
(Jan 28, 2013) john said:
looking at a house for sale and noticed that when they built an addition, the kitchen sink cleanout was not moved and thus now inside the house! is this okay? Fyi I'm in California
It is common for plumbing cleanouts to be located inside a building.
(Mar 15, 2013) Dean said:
Got a leak fixed in my house and the central heating hasn't worked properly since it comes on some days and not on other days can anyone help the plumber hasn't a clue
Search INspectAPedia for
Air Bound Heat
to see a possible cause and cure for the problem you describe.
(Mar 19, 2013) Rick said:
I have a well system in my house. Recently have begun to have pressure loss in the system. Ex. If i flush the first floor water closet the sink righf next to it does not have full pressure or volume. This will hapen elseware in the house also.
The pressure tank is a goulds pumps v60, 20 gal. 30/50 pressure settings.
If test the air pressure it is at the reccomended psi. 28/50.
If shake the tank with the punp off and system drained I do here water inside.
It takes about 15 sec. For the level to drop to turn the pump on and about 30 sec for it to recover. I took that data while running the washing machine. Which is right next the tank.
The tank is about 8 yrs old. There is no water or air coming from the shrader valve.
Let's try to clear up pressure vs flow. When no water is running, the static pressure, read on a pressure gauge, in your water system will be somewhere between 30 psi (the cut-in pressure) and 50 psi (the cut out pressure on your system).
The flow rate, in gallons per minute that you observe at an individual fixture, depends not just on the system pressure but also the diameters of all of the pipes in the supply circuit. If, for example, water pipes are partly clogged, you'll notice that the flow rate will be reduced.
If we run water fast enough or at enough fixtures such that the well pump runs continuously, then the pressure and flow we will see at those fixtures depends on the piping (diameter, length, number of bends, obstructions, friction losses) and the ability of the pump to send up water at a given pressure and flow rate.
In the Related Links at page top, click on WATER PRESSURE LOSS DIAGNOSIS & REPAIR - home - to read how to diagnose and fix problems with water pressure or flow.
(Mar 19, 2013) Rick said:
Well I understand what your saying. I guess my point is that this has just started happening a few weeks ago. I have not changed anything in the system nor had any other issues. With pipes or faucets. My concern is my pressure tank. Confused with the psi being ok but hearing water in it.
We're not giving up. But to be clear, the pressure tank does not provide much by way of water pressure. The pressure is provided by the pump or in municipal supply, the pressure in the water mains.
When we see pretty good pressure at a single fixture - say a faucet - and water pressure falls off significantly when a second fixture is running, usually that points to pipe clogging.
But if your complaint came on suddenly it makes sense to look elsewhere - even a partly closed supply valve could explain your observation.
(Mar 12, 2014) Steve O said:
Hi. My home is about 14 years old and yesterday while I was in the basement I heard what sounds like someone knocking on the wall. This is coming in the vicinity of the drain pipes (PVC) that come from the second floor of the house. This went on for around two hours. A knock here followed by half a dozen a few seconds later.
It eventually quit doing this and did not reoccur until the second half of the day. Today, the same thing happened but it stopped much quicker. I flushed a toilet in the basement around noon on the opposite side of the basement and now it has started again. What could be causing this? HELP!!!
Please search InspectApedia (you can use the Search box just above) for
And check out that diagnostic article.
I suspect that's what's going on at your home. Water hammer is caused by water moving at velocity through building piping; I've found that banging pipes can get started and then continue for a while as water continues to run somewhere, affected further by the security of pipe supports as vibration can make pipe bang on their mount points as well.
(Sept 9, 2014) Phil Putnam said:
Is the new "Pex" water line latex free?
(Oct 5, 2014) Martha Metter said:
we had a well company come out and fix a cracked pipe at the head of the well. They said they raised the pump at least 5 feet or more and cut off a section of pipe. They dropped the pump into the well bottom more than several times. 3 days ago the water in house spewed heavy sediment from every faucet and shower/toilet etc.
Then clogged up everything. I called the well co. back, they came out and told me I need to get a plumber in here to flush out the pipes. How do we get the sediment out of our pipes, and is this the well companies responsibility to pay for the work?
A plumber will open strainers, remove shower heads, etc. to help flush debris from the system. It might be necessary to partly drain tanks such as a water heater or pressure tank as well, of course change any water filters afterwards.
I can't address the question of who pays for this work as I cannot assess responsibility. Any work on a well, even if nothing unusual happens during the job, might stir up debris from the well bottom.
(Oct 17, 2014) Gfgayle said:
We live in a suburban home that is furnished by a water plant system. Lately, the water has been coming out very erratically. It comes as though I was turning the faucet on and off very quickly. Can you recommend any corrections?
(Oct 24, 2014) Anonymous said:
We have a restaurant and have replaces all the plumbing in the place, but now we have a strong sewage smell in the build. Where did we go wrong.
(Oct 24, 2014) Frances said:
We have an old restaurant and recently we replaced all the plumbing, but now we have a strong sewage smell in the build and can't seem to find the source. Please help.
(Oct 29, 2014) Terry said:
When the toilet is flushed water splashes up, appears to be releasing air, out of the bowl sometimes so strong it goes onto the floor?
Terry that sounds like a blocked drain
11/11/2014 Ryan said:
I put in a new jet pump and pressure tank set to its proper settings for the pump and installed a new check valve before the pump. I can't keep pressure at any of my faucettes
Ryan check out the water pressure diagnostic procedures beginning at
WATER PRESSURE LOSS DIAGNOSIS & REPAIR - in the More Reading links just above
or in the detailed article links at page left click on WATER PRESSURE PROBLEM DIAGNOSIS TABLE
(Nov 18, 2014) m shabbir said:
The draiage bad smell in office feeling at evening time or at any time
while there is no any toilet and water supply and draiage system
.The office area is 10*10m2 .
(Nov 23, 2014) Paul said:
my parents have a new 1-2 flush toilet and at night it makes a noise like it was just flushed,I think there is air getting in somewhere,please help.Thanks
I suspect that the flush valve is leaking slowly into the toilet bowl. Eventually the toilet fill control figures that the cistern or tank is too low and goes through a re-fill cycle.
(Dec 16, 2014) Bob said:
I have a problem with air in my system..air bubbles in the water, bursts of air, and a pump that hunts when it starts and as it is pressurizing. The pump shuts off at 55 psi, and then fairly quickly falls back to about 39 psi, and then seems to stop. The water for the system is pumped out of a lake. There is a foot valve in the lake, and a check valve at the pump.I have two bladder tanks, but both ring hollow when I tap them. The only other things in the system are a string filter, a carbon filter ,and a UV filter. I suspect that I am losing pressure back though the check valve and foot valve, but am a little mystified as to why the pressure drops so quickly to about 39 psi, and then basically hangs there. The pump does not seem to cycle more frequently than it ever did. Any suggestions? Great web site by the way. It helped me understand how to set up my system pressures when I put it in.
Please try the diagnostics at
and let us know how you succeed
(Dec 17, 2014) Anonymous said:
After reviewing the different possibilities, I think that the most likely cause is a leak back through the check and foot valves. I changed the pump out last spring but used the same check valve. The pump that I replaced had some hard deposits in it. I checked all of the fittings I could think to check and tapped the check valve while the pump was drawing to see if possibly there were loose deposits preventing a good seal. I do the trick I'll try replacing the check valve.
Reply: that sounds reasonable
(Dec 20, 2014) Anonymous said:
After a couple of days, the air in the system has decreased. Either I tightened a loose connection or tapping the check valve helped.I'll keep an eye on it for now. there is still some air, but it might still be clearing out. Thanks again for your help and for this site.
Thanks for the feedback. Indeed on water systems I've occasionally found air entering the pressure tank and piping at a slightly-leaky plastic line connection between well and pump; we could see the air showing up as bubbles in the clear plastic that contained the water filter. On tightening the hose clamps and adding a second clamp at two suspicious fittings the air entry stopped.
23 Feb 2015 Fran said:
Is there a heater for a submersible well pump to prevent line from freezing
Fran there are drain-back systems that can prevent the well line from freezing and depending on which well line section is freezing, outdoor (or indoor if it's inside) rated heat tapes might suffice.
We discuss well line freeze protection at
And pump protection devices at
(Mar 5, 2015) Marty said:
I have water leaking from a door frame in my 1st floor apt. There is a bathroom on the 2nd floor directly above mine. For the past two weeks I have been trying to pinpoint where the water is coming from. It does not show up immediately sometimes it takes a week before water drips from the door frame. I am trying to isolate by using one thing at a time in the 2nd floor bathroom. My plumber and I are stumped as to where the water is coming from. We are now ONLY flushing the tiolet to see if that is the source of the water dripping down. I have also ONLY used the shower/tub to see if the water is coming from when we use the shower/tub. It has been such a mystery to understand where water would be coming from that could seep into a door frame and drip down. Any advice, information, insight, or suggestions.
See LEAK TYPES WATER SUPPLY or DRAIN PIPES
In the master index found at More Reading above for some suggestions on tracking down just this sort of problem. Please let me know what you find after talking a look at that article.
(Mar 10, 2015) jackie dunadee said:
I cannot get hot water upstairs ,I get real hot water downstairs with no problem but now with ababy ,I want to bath him in tub upstairs . I have a half bath down with shower and full bath upstairs,any suggestions?
If the water never gets hot I suspect that there is a plumbing connection problem.
If there is no water at all I suspect a blockage or a closed valve.
If you find that water ultimately gets hot after running a long time, the solution may be to add insulation to the water pipes.
Don't scald the baby.
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