10 Common Plumbing DIYer Mistakes, and How to Fix Them!




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Learn how to avoid costly mistakes by following this article and video!

Step 1: Teflon Tape

Putting teflon tape on the wrong way. Teflon tape can be installed correctly or incorrectly. The incorrect way of doing it is installing it in a counter-clockwise fashion. If installed this way, when tightening your fitting, it’ll tend to wanna unravel itself, thus removing it and potentially creating a small leak, so always install it in a clockwise manner.

Step 2: Improper Venting

Number 2 is improper venting. A lot of DIYers aren’t aware that a plumbing system needs to be well vented. Just like the straw phenomenon, if you don’t allow air in back of the waste going down a pipe, it’ll wanna find air somewhere such as a ptrap and it could cause unpleasant odors to appear from the system so always make sure to inform yourself when attempting to do this kind of work.

Step 3: When to Stop Tightening

Number 3, Over-tightening a fitting. Fittings aren’t made to be over tightened, if you over tighten one, you may have a risk of leaks or even break a fitting as I’ve already seen before. The trick to knowing when to stop is to measure the threads inside the fitting, for example, a 1/2” of threads indicates it shouldn’t go in more than ½”.

Step 4: Saddle Valves

Number 4, installing a saddle valve on a potable water system. These valves are really ingenious but are very prone to leaking and are banned in most places. You’ll still see them in your local hardware stores but it’s highly recommended not to install them. The correct way of branching off a water line is to cut the pipe and solder or crimp a Tee fitting and you are sure to never have any problems this way.

Step 5: Don't Use Drano!

Number 5, is using harsh chemicals to unclog a drain. Most times, the first step for a DIYer to unclog a drain is to use chemicals such as Drano or Drain-Aid. This is a viable solution but it can damage your pipes in the long run if you abuse of it. The solution, pour 2 parts vinegar and 1 part baking soda into the drain, it’ll sizzle and might just loosen the clog enough to unblock it and plus it won’t damage your pipes!

Step 6: Don't Forget to Shut the Water Off!

Number 6, cutting a live pipe without shutting off the water. Most repairs need the water shutoff and a lot of people tend to skip this part and get a big surprise when cutting into the pipe, yikes! The solution is to always make sure the section you are working on is properly isolated before attempting to cut it. If there is no valve nearby, close the main water valve and drain all the water before proceeding to any kind of repair.

Step 7: Transitioning From Steel to Copper

Number 7 is connecting a copper line to a steel pipe. Often, you’ll need to transition from steel to copper and there is a right and wrong way to do it. If you join these two dissimilar materials together, they’ll corrode and eventually fail, causing water damage. To resolve this, you need to either use what they call a di-electric union, or just a brass nipple to join them together, this way you’re sure it’ll last for many years, and you don’t have to worry about anything.

Step 8: Wipe Your Flux Or...

Number 8, is soldering and not wiping the left over flux. Flux is basically an acid that prevents oxidation when soldering a joint. This so called acid is strong enough to eat thru a copper pipe if not wiped off, again, creating a pin hole and wreaking havoc on your property. The fix? Always wipe any excess flux after soldering, it takes 5 seconds to do and can save you a lot of trouble in the long run.

Step 9: Overheating When Soldering

Number 9 is overheating a joint when soldering. Like I mentioned above, your flux will prevent any oxidation while soldering. However, if it’s overheated as such, the solder won’t flow properly into the joint and could cause a leak. To prevent this, don’t overheat the joint, before the flux becomes black and burns off, move the heat away from the joint and apply your solder.

Step 10: Using a Pipe Cutter the Wrong Way

And number 10 is tightening a pipe cutter too fast. I often see apprentices cinching down on it on the first turn just like this. This could result in 2 things, 1, a broken cutting wheel and 2 a deformed pipe which isn’t good. So in order for this not to happen, you should only turn the knob ¼ turn for each complete rotation, this way you’re not applying too much force on the wheel and you won’t get an out of round pipe.



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    29 Discussions


    17 days ago

    Saddle valves should not be installed inside Wall's. If saddle valve has to be in the wall, I strongly suggest installing an access panel to access the saddle valve, out her thing juilo neglected to mention was , upon completion of valve installation, make sure packing nut on valve stem is tightend, not too tight ,the stem won't turn closed,tight enough you feel some friction, closing..
    reguards to cleaning sweat joint(copper)after soldering.. I carry a spray bottle of water , after heating,lightly mist your work,untell solder solidifies (hardens), then quench and wipe with a rag.. if you quench with lots of water , right after soldering , potential of the solder cracking ,leaking,. Lightly mist ,tell solder solidifies changes color .. also acts as fire extinguisher..
    Why would you show a dia letric union connected to black pipe?? Domestic water is galvinized pipe, not black pipe!!! Black pipe will rust shut , in a short time... Now I see someone going under their house and cutting there gas line and blowing up!! Or installing BLK pipe on domestic water system.. fulio by you making this instructible ,tells me you don't know what you are doing!! Showing wrong material , dude if you want to show diy'ers how to do plumbing show them the right way with proper material used in domestic water systems.. I personally don't like dia letric unions, I've seen them rust up closed ,inside 3 years of beeing installed and the rubber washer usedn the union will break ground connection I prefer using 6 inch brass nipple, here in the states minimum 4 inches of brass to connect copper to galvenized pipe.. if any grounding wires connected to any pipes removed , must be re installed with appropriate clamp .. no steel grounding clamps on copper pipe...
    electrolisys is what happens when copper is connected to steel ,water moving thru the pipe
    is the energy causing the 2 metals to eat each other along with water quality....... black pipe is not to be used on domestic water systems

    2 replies

    Reply 17 days ago

    PlumberMike, watch the video again...You'll notice that I don't mention any potable water lines connected to the steel piping, that is against code. A boiler, for example, has a copper supply/return, and most heating systems use steel piping, this is where you would install a dielectric union like I've done hundreds of times. You should read/watch properly next time before posting a comment like this, smh.


    Reply 15 days ago

    Im a certified boiler tech. I'm familiar with closed loop systems, and the steel piping, volactic fittings , but on all closed loop systems are you aware that chemicals are added to system periodically, to prevent corrosion to the steel piping??
    I'm not trying to make you look bad, or talk crap.. if your going to post ,how to diy instructables, for the whole word to see ,post using proper methods ,material and safety prosedures, and health hazards associated with the perty much all consumables ( glues,fluxes, etc)used in the plumbing trade,tell them to read all directions ,and warning lables before starting any project...read the back lables..some people are sensitive to chemicals , some more than others...
    I don't watch the videos attached to instructables, I didn't watch your video..
    I'd like to make couple suggestions what I think diy ers want to see, show them how to install garbage disposal , or install 2 part waste and p-trap, repair leaking shower valves, or change out pilot on a water heater or how to flush a water heater to remove sedement from tank, change out faucets , how to install a pop-up assembly ...I appoligize if I came across as a bully ,but my 27 years in the plumbing trade comes out when I see improper methods,or material being used, I will let them know what they are doing wrong, to make them better.. Julio keep on doing what you're doing.. happy holidays..

    JulioC150Randolph Garrison

    Reply 25 days ago

    That's just the ratio, it's up to you to choose how much you want to put in your drain ;) You could put 2 cup of vinegar and 1 cup of baking soda.


    4 weeks ago on Step 10

    This is such a fine, straightforward and helpful Instructable that';s it may be churlish of me to pretest against the use of 'wanna' for 'want to,' but there it is. In any event, readers should pay close attention. In step 3, note that JulioC150 uses TWO wrenches to tighten. Using only one often results in out-of-round thin-wall tubing. Aggressive tightening of pipe cutters probably ruins more copper tube than anything else, although the warning re overheating and not wiping excess flux are important. Another point against Drano is its high cost. Mixing vinegar and baking soda will produce chlorine gas, but hardly enough to be dangerous. Still, if you're worried--Open a Window! Or mix some ordinary flour with dish-washing liquid--cheapest kind--to make a thin, pourable paste. That will often unstick hair clogs. Whatever you use, give it plenty of time to work. And heed JulioC150 re saddle valves. So simple! So ingenious! So cheap! But they WILL fail sooner or later and, since they're usually hidden behind drywall--that mess will be beyond horrible.

    3 replies

    Reply 27 days ago

    Mixing vinegar and baking soda will produce chlorine gas
    NO IT DOES NOT PRODUCE CHLORINE GAS!!! there is NO Cl in the mixutre.
    It produces carbon dioxide which in the quantities coming out of this mixture is harmless.


    Reply 4 weeks ago

    Vinegar and baking soda produce CO2, not chlorine gas. If you're getting chlorine gas from either of these ingredients, you need to switch brands. :p
    For reference, heres the chemical reaction of vinegar and baking soda:
    NaHCo3 + CH3COOH= Co2 +H2O + Na+ CH3OO

    As you can see, there is no chlorine (atomic symbol Cl) in the equation.

    Not trying to call anyone out, just wanted to offer a correction. :)


    4 weeks ago

    #5 If the clog is in the kitchen sink, try this first: pour an entire kettle of boiling water down the drain. The clog is most likely cooking grease that was liquid when you dumped it, but solidified in the pipes where they were cooler. The boiling water will melt it again. Better yet, put some dish soap in the boiling water so it will mix the grease with the water. If the clog is in the bathroom sink or tub, go to a hardware or big box home store and get a tool that looks like the fishbones of a eel. it's a strip of flexible plastic with barbs on it. you work it down into your drain as far as you can go, then pull it out. The clog is most likely hair and that should pull all or most of it out. If those cures don't work, THEN try the drain cleaner (and I've always had good results with Drano).


    4 weeks ago

    #12: Use Teflon tape when joining plastic pipes and fittings, and use hemp when joining metal pipes and fittings. Prior to putting hemp on the metal threads, drag a metal saw blade sideways across the threads to create little notches that the hemp can grab on. Some threads conveniently come pre-notched. Again, the hemp should be applied clock-wise. You can add a dab of acrylic caulk and spread it over the hemp. This helps to keep the hemp in place and lubricates the threads.

    From the day I started following this rule not a single joint has failed on me: Water proof instantly and in the long run.

    4 replies

    Reply 4 weeks ago

    Always good to know, I think hemp is used more in the Uk than here, if you could clear this up, that would be great.


    Reply 4 weeks ago

    Honestly, I don't know about the UK, but you may be right. I live in Germany and even though modern materials like Teflon tape or compound pipe have been coming up over the past decades, some of the more traditional methods and tricks will never vanish because they are still applied with success and even may have some advantage over the modern stuff.

    Franks InstructablesAzze01

    Reply 4 weeks ago

    When speaking about Teflon tape it's always good to know that the yellow tape is for gas and white is for water. The yellow can be used for water but never use white Teflon tape for gas.


    4 weeks ago

    Thanks! Knew most of these, but your style of informing and reminding is easy to read, vs the common, heavy handed “leave this to the pros” approach.
    How about adding the benefits of primer, and not relying too much on compression/slip fits for sink drains?
    Oh, and turning off the sink or toilet water cock, without having a Repair valve on hand?
    Thanks again!

    1 reply

    Reply 4 weeks ago

    Yes I am starting a new article and video about this, thanks for your input!

    Supernerd Sven

    4 weeks ago

    Vinegar and baking soda are a good altenative to industrial drain openers. However, they should never be mixed because the reaction between an acid and a hypochlorite (common in drain cleaners and bleach) produced chlorine gas, which is deadly and odorless.

    In general, cleaning products should never be mixed because we generally don't know their contents (as it's proprietary information) and most of us don't know how the chemical components of different cleaners may react.

    Would you mind adding a warning to step 5 for the safety of readers who don't know this?