© Eugene Brennan
Basic plumbing isn't rocket science. If you are reasonably adept at DIY, understand the basics, and take care when putting it all together, it's not too difficult. This is a comprehensive and easy-to-understand guide to pipe types, plumbing fittings, thread sizes, with instructions for how to use fittings to connect copper, PVC, and PEX pipes.
WARNING!
Remember, if you're a novice attempting DIY plumbing, be prepared for the odd leak from water fittings that are over or under tightened and don't make joints where they're inaccessible (e.g. inside walls). Never attempt gas plumbing as an amateur, leave it to the professionals.
Plumbing pipe is made from various materials, including copper, galvanized steel and iron, polyvinylchloride (PVC), chlorinated polyvinylchloride (CPVC), cross-linked high-density polyethylene (PEX), and polybutylene. Fittings are made from brass, plastic, copper, or malleable iron.
Note that local authorities who replace lead pipes may only do so up to the threshold of the property or the main stop valve/water meter and it is up to the property owner to change from consumers side of valve/water meter.
A note about plastic piping: Care needs to be taken when working near plastic piping or fittings to avoid heat damage from blow torches or other heat-producing tools. Piping should also be routed during installation so that it isn't subjected to high temperatures from heat sources such as flues.
Domestic copper and plastic plumbing are technically referred to as tubing. Steel and heavier gauge plastic plumbing is referred to as pipe.
Iron and copper are dissimilar metals. Without the proper precautions the two metals in close contact can act like a battery resulting in galvanic action which can cause corrosion. So precautions need to be taken to avoid this and the details are outside the scope of this guide.
© Eugene Brennan
© Eugene Brennan
Fittings are made from various materials, including plastic, brass, copper, and iron. There is a huge variety of types with different functions, including 90° and 45° elbows, offsets, T-joints, Y-joints, cross joints, gate valves, ball valves, non-return (check valves), reduction fittings, couplers, and flange (bulkhead) fittings for making a connection to oil or water tanks.
Push fittings can be used with copper, CPVC, and PEX tube, but aren't suitable for PVC. See Connecting PEX to PVC for more details.
For large projects, the cost of push or compression fittings on PEX can mount up. A cheaper alternative is crimp fittings, which are slimmer but must be installed using special tools. See How to Install PEX Tubing—Making a Crimp Connection.
© Eugene Brennan
© Eugene Brennan
A union fitting enables two parts of the fitting to be attached to each other without having to turn the whole fitting or attached pipes.
© Eugene Brennan
© Eugene Brennan
FIP and MIP (female iron pipe and male iron pipe) are terms sometimes used to refer to the shape of the threads on a fitting. For more info and sizes, see the reference section at the bottom of this article.
© Eugene Brennan
Pipe Sizes and Standards Can Be Somewhat Confusing
For example, if you measure a 1/2 inch pipe or 1/2 inch fitting, neither the internal or external diameter of the pipe nor the diameter of the thread are necessarily 1/2 inch. It is only called 1/2 inch for historical reasons. This dimension originally referred to the internal diameter of a pipe used with the 1/2 inch fitting, which in the early days of manufacture would have been thick-walled.
© Eugene Brennan
Copper or plastic tube can be cut with a hacksaw. However, if you use a pipe-cutting tool it gives a cleaner, squarer cut without burrs. The tool in the video below can be used to cut copper tube. It can cut plastic tube also with a little bit of effort, however, plastic pipe-cutting shears do a better job. Tighten it gradually after each couple of turns. If you tighten it too quickly, it can deform the end of the tube. If you use a hacksaw on copper pipe, file off any burrs afterwards.
You can buy a similar product on Amazon here
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
You can't just grasp the two ends and bend because the pipe will kink in the middle. There are several techniques for bending copper pipe:
Image by permission Draper Tools Ltd
© Eugene Brennan
It's possible to overtighten these joints, resulting in a leak which can't be remedied without cutting back a section of tube and replacing the olive. If a joint is inside a wall or under a floor, there's obviously the potential of water damage. If water gets into electrics, there's the added danger of electric shock or fire. So if you attempt making these joints in a DIY capacity with no prior experience, it's wise to do so where leaks won't be an issue, if they occur.
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
These type of fittings vary somewhat, but in general, this is the procedure for using them:
The video below shows how to use Sharkbite twist lock fittings. These are the simplest to use for connecting both copper and plastic pipe.
Push fittings are easy to use, but the jury's out on whether the neoprene “O’ rings used in many push fit joints or fibre and plastic rings can degrade over a long period of time due to ageing or extreme temperatures. There's also the risk of pinch and crush damage. So if these fittings are used, it's probably wise not to situate them where they're inaccessible. E.g. Behind tiled walls in bathrooms.
If you need to connect a new appliance to an existing PEX tube, you'll need a T-fitting like this Sharkbite one available on Amazon.
Courtesy of Sharkbite
A kit from Amazon compromising of the most common push-fit SharkBite fittings. These including a pipe cutter, deburring tool to remove sharp edges, disconnect tongs, straight couplings, elbows and end caps for blocking the end of tubing.
Capillary fittings require some skill in order to be assembled properly; however, they are the cheapest, neatest and strongest solution for joining copper pipe.
Copper pipe and capillary fittings are "sweated" together. This involves heating the pipe and fitting so that solder melts and holds the joint together.
WARNING !!!
Be careful when using a blowtorch and take suitable precautions to avoid starting a fire. Adjacent plastic plumbing and wiring can easily be melted. Fireproof mats are available for placing behind fittings during heating. A ceramic tile can also give some protection, but avoid directing the flame directly on it, as it can shatter.
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
Steel pipe with a screwed end, normally has a tapered male thread which mates with a female thread on the other fitting. PTFE plumbing tape or other proprietary thread sealing cord wrapped around the threads increases lubrication and enables the male thread to be screwed in tighter to produce a watertight seal. The secondary benefit of the tape is to fill the gap between the female and male thread, helping to seal the joint. The tapered threads of brass fittings and bibcocks are also sealed with PTFE tape. PTFE tape is also used with brass fittings.
You can also smear pipe dope (jointing compound) over the tape on the joint to improve sealing in case the tape catches on the threads and rolls around as the fitting is being screwed into place. Traditionally hemp and jointing compound (Boss White, Plumbers Mait) were used for sealing joints. For some applications, if temperature is excessive, PTFE tape may be unsuitable, and jointing compound can be used.
Sometimes both male and female threads are parallel in which case they are supposed to be sealed using a fiber washer or O-ring which is compressed by a flange on the fitting. This is often the case with a spigot (outside tap) or a hot water tank. A tapered fitting would possibly result in the fitting tightening suddenly with the spigot at the wrong angle. A washer however allows more leeway as regards tightening the fitting to the correct angle
There is a certain degree of trial and error when winding tape onto fittings. If they are made to a tight tolerance, only a few layers of tape may be needed. Sometimes if fittings are a loose fit, extra tape may be needed (4, 5 or 6 turns).
© Eugene Brennan
© Eugene Brennan
© Eugene Brennan
ANSI B1.20.1 - NPT - American National Standard Taper Pipe Threads. Engineering ToolBox. (n.d.). Retrieved December 4, 2022, from https://www.engineeringtoolbox.com/npt-national-pipe-taper-threads-d_750.html
Wikimedia Foundation. (2022, October 13). British standard pipe. Retrieved December 4, 2022, from https://en.wikipedia.org/wiki/British_Standard_Pipe
Wikimedia Foundation. (2022, September 1). Copper tubing. Retrieved December 4, 2022, from https://en.wikipedia.org/wiki/Copper_tubing
Jackson, A., & Day, D. (1993). Collins Complete DIY Manual. HarperCollins.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Question: Can I connect a 1/2 T pipe to the main 3/4 water copper pipe, one end of the T goes to the washer, the other end goes to bath faucet?
Answer: Possibly, you'll need either a T if it's available with a 3/4" outlet port and 1/2" ports on the two ends of the T. Alternatively a 3/4" T could be used with inserts in the other two 3/4" ports to drop them to 1/2" (this is for brass fittings). The inserts are just brass rings that reduce the inlet to 1/2". I'm not a plumber so I'm not going to give advice and there may possibly be regulations about how this is done and other complications. Maybe post the question on a plumbers forum.
Question: I am attaching a brass fitting to the threads of black pipe in a natural gas application in order to get to the flex line to the appliance. Or is it better to use the stainless steel, or whatever material it is that comes with the gas connection kits? This is an outdoor application, so I thought brass would hold up longer, but I'm not sure about the dissimilar metals factor?
Answer: There could be an issue with dissimilar metals and Galvanic corrosion. Indoors since water isn't going to get into threads in a gas connection, it's not an issue, but outdoors it may be a different story.
I'm not a qualified gas plumber/fitter, so I'm not going to advise you.
You could post on one of the several plumbers forums and they might be able to advise you, but will probably refer you to a professional.
Question: Can Pex or PVC pipe be chased into a wall? I'm guessing maybe something like pipe insulation might be prudent to allow for expansion and contraction as well as protecting the pipe itself from the mortar?
Answer: I don't see why not as long as it's well insulated. PEX is also resistant to bursting even if it freezes. Metallic tape is supposed to be wrapped around the plastic pipe so that a metal detector can be used to locate it if any fixings need to be inserted in the wall in the future. It'd also be prudent not to have any joints in walls just in case they leak. I'm not a plumber, so maybe try posting on this forum to double check (or an alternative forum if you're in the US or other country that may have different regulations):
https://www.ukplumbersforums.co.uk/
Question: I recently had our kitchen faucet changed and now we get a terrible chemical taste only from that faucet, could there be something wrong with the faucet?
Answer: Have you spoken to the manufacturer/retailer? Sometimes plastic (which would be used in seals) has a smell or produces a taste from residues left over from the manufacturing process (e.g. the distinctive smell of PVC or taste from water left for a period in a plastic bottle). Try running the faucet for several minutes and see if it improves the situation.
Question: What is used to connect a 5/16 inch rubber tube through a hole on a one-inch copper pipe? The system I have that the rubber tube is inserted with a piece of one-inch PVC tube half way and the PVC tube is then inserted into the copper pipe through the hole. The one that came loose can be easily pulled out. I do not see anything on the PVC tube, glue or cement. Other fittings cannot be pulled out easily. Can you tell me how this is done so that the plumbing will not leak?
Answer: If the system isn't under pressure, possibly some form of grommet arrangement could be used to suit the hole in the copper and then the rubber tube would feed through the grommet. This system is sometimes used for fuel lines exiting tanks on e.g. string trimmers.
Question: I accidentally drilled a hole in the water feeding pipe. This pipe is totally cemented into the wall. Is there a quicker solution besides chopping the wall open, bending the pipe a bit and putting in a joint, be it soldering or compressing? What is the best solution?
Answer: Hi, there's a couple of suggestions here:
You'll probably have to clear a space around the burst to insert a section of new pipe or a repair coupler.
http://www.diydoctor.org.uk/projects/repairing_a_b...
Two-piece clamps with a rubber shell are also available for emergency repairs but are only a temporary measure until you fix the pipe properly.
https://www.diy.com/ideas-advice/how-to-deal-with-...
© 2015 Eugene Brennan
Eugene Brennan (author) from Ireland on May 02, 2019:
Thanks for the correction Erik.
Leave a comment if you see any other errors.
Erik on May 02, 2019:
NPTF is not npt Fine. NPT Fine does not exist as denomination.
NPTF stands for National Pipe Taper FUEL. (see Ansi B1.20.3).
The sealing requirement of tapered fittings used where fuel is involved are stricter than plumbing, so while the thread is the same of an NPT the difference comes in the smaller and bigger diameters of the threads and their roots and crests. They are both tapered thread designed to give a seal biy jamming a male in a female fitting but the NPTF have less chance of leak (no pipe dope or teflon tape is allowed)
Lloyd on February 25, 2019:
I have a 3 inch copper that I need to stop up a hole about 2 inches what can I use
Stephen on July 31, 2018:
The picture of the "Outside faucet or hose bibb" is actually called a boiler drain. If you put that on the exterior of your home, it would burst first time it freezes. The exterior faucets have stems that seat far enough into the foundation/crawlspace so that even if they ever do freeze, the main plumbing is not affected by it.
Eugene Brennan (author) from Ireland on June 03, 2018:
Hi Robert. It sounds like the system used on my hedge cutter. The fuel lines are rubber and simply exit the tank through a hole. The hole is smaller than the rubber tube so the plastic of the tank around the perimeter of the hole digs into the tube, sealing it and stopping the tube from pulling out. Because your pipes are copper, the rubber tube probably doesn't pass directly through the hole because the sharp edge would probably cut into it, so I'm guessing that's the idea of the PVC which is harder.
I don't know whether this is a standard way of doing things or just a made up arrangement. Presumably if it's standard, new PVC tubing of the correct diameter is available,
Robert Huang on June 03, 2018:
I have a radiant heating system. The water is distributed to a zone with one inch copper pipe and it is further distributed with 5/16 inch rubber tubing. The tubes are inserted to the copper pipe through a hole in the copper pipe. One of the tube came loose and it is easily pull out. The tube is inserted to a small piece of pvc tube and the pvc tube is then inserted tthrough the hole to the copper pipe. I do not see any thing on the pvc tube or any glue or cement on it. Can you tell me how it is tightly fitted to the copper pipe? The other rubber tubbing cannot be pull out easily. Thanks a million.
Eugene Brennan (author) from Ireland on June 02, 2018:
Thanks for the appreciation Kristen!
I'm glad it was of help to you.
Kristen on June 02, 2018:
Great article. I try to be independent plus I hate to pay a repairman $$$ for something that really isn’t hard or time consuming. I recently changed my kitchen faucet by myself. IT only took me 3 days and lots of googling!
I am now trying to replace outdoor faucets and pipes. So thankful I found your article. Very informative and in layman’s terms. Thank you.
steve on April 24, 2018:
Thank You! helped me out a lot!
Nic Rollins on March 22, 2018:
Thank you for your very clear and easy to follow article. You have answered some of my very basic questions.
Eugene Brennan (author) from Ireland on January 31, 2018:
Hi Gene,
I'm not a plumber so I can't advise however my own washer outlet feeds into a 40 mm standpipe and I've never had an issue. According to plumbing code, drain pipe has to be sloped a minimum of 1/4 inch per foot. For shorter runs, the gradient needs to be greater since the waste pipe has less length to "store" the water and must discharge it quicker as it fills. Also traps must be 2" for washers (US code).
Have a look at these links:
https://books.google.com/books?id=OMVc-nTpqwAC&...
http://homeguides.sfgate.com/plumb-standpipe-64746...
http://homeguides.sfgate.com/washing-machine-need-...
Gene on January 31, 2018:
I am running a 2 inch stand pipe down to a 2 inch to1 1/2 by the cement floor. The 1 1/2 inch line does go back to a 2 inch line under the floor. This should drain well or not?
Hastadur Pun on August 31, 2017:
Very useful article
Eugene Brennan (author) from Ireland on August 05, 2017:
Hi Richard,
This may be of use to you:
https://en.wikipedia.org/wiki/National_pipe_thread
I did a Google image search using these terms, it might help you find what you need:
npt pipe fitings 3/16 elbow compression to female
Richard Murphy on August 05, 2017:
Are steel tube fittings and copper tube fittings the same thread, NPT? I am trying to find a Fitting to connect a Steel Heat Riser Tube to my Autolite 4100 Carburetor's Choke. The Compression Nut measures .1875" = 3/16" x 24 and this Nut fits on the Cast Fitting on my Carb's Choke. BUT this cast fitting points toward the Firewall at a 45 degree down angle. I need it to point toward the right/passenger side wheel well. A 90 degree street elbow with the 3/16" (with a Female NPT is what +
++++I THINK is what I need.the Compression Nut, Olive Ring and Steel Tube are .1875" = 3/16".) I can find a 90 Elbow that is 3/16" Compression on one end but CANNOT find a 3/16" FPT for the Choke end. I THINK the cast fitting on the Choke is NPT and I need a Female on the Choke end. OR maybe 2 fittings that would accomplish the same thing. Can you confirm that Steel Tubing and Copper Tubing fittings both have NPTs? Might you know of a source for this (apparently) oddball fitting?
I have spent yesterday and today searching the web with no results. Murphy's Law = and I am Murphy! Thank you, Murf
Eugene Brennan (author) from Ireland on September 18, 2016:
Loctite 55 pipe sealing cord is supposed to be good for sealing and locking a tap in place. It allows a 45 degree realignment which isn't possible with PTFE tape. An alternative is to use hemp and jointing compound. Another suggestion I've come across is to form a taper on the threads when winding PTFE tape. This is so that instead of having parallel threads, you now have a taper which will wedge tightly as you tighten.
It's actually better to feed the supply line into tap from above because in freezing conditions, the shut off valve indoors can be turned off, and the tap turned on to drain the line and tap body. If the feed is from below, everthing will stay filled up and freeze.
Woking Mike on September 18, 2016:
With regard to your picture of the brass tap and the wallplate; it would be helpful to explain how to deal with the fact that when you screw the tap onto the wallplate it finally tightens with the tap at a random angle. With the 15mm pipe coming up into the compression joint, how do you make the tap tighten when it is pointing downwards.
If you have any questions on t type tee joint. We will give the professional answers to your questions.