Plumbing Interview Questions & Answers

  1. Question 1. Explain What Is The Primary Step To Unclog Any Blockage In The Pipes?

    Answer :

    First and primary technique to unclog the blockage is to pour hot water through the pipes. If the blockage still remains then, you need to use other options.

  2. Question 2. What Is Referred As Building Drain?

    Answer :

    The lowest point in a drainage system where the interior drainage pipe meet and are conveyed into the sewer is referred as Building Drain.

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  4. Question 3. List Out Some Of The Most Common Tools Required For Plumbing?

    Answer :

    • Adjustable pipe wrench
    • Faucet valve seat wrench
    • Faucet valve reseating tool
    • Faucet packing and washers
    • Tubing cutter
    • Teflon tape
    • Cup plunger
    • Flange plunger
    • Closet Auger
    • Sink Auger

  5. Question 4. What Skills Does A Plumber Should Have?

    Answer :

    • Problem solving
    • Critical thinking
    • Listening and paying attention to instruction
    • Decision making
    • Co-coordinating
    • Technical knowledge related to pipe fitting

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  7. Question 5. What All Tools Are Required To Unclog A Sink?

    Answer :

    • Cup Plunger
    • Duct tape or wash cloth
    • Sink Auger
    • Channeled type pliers
    • Bucket

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  9. Question 6. Mention What Are The Different Types Of Chemical Drain Cleaners Are Used?

    Answer :

    • Caustic drain cleaners: It contains a substance like caustic potash; they are bases and give electron to the clogging substance. This reaction will generate a lot of heat and dissolves the clogging substance, and clears the blockage.
    • Oxidizing drain cleaners: It contains chemicals like household bleach, peroxides and nitrates. These chemical cause the organic material of the clog to lose an electron and become oxidized. It also generates heat and gas, which clears the blockage.
    • Acid drain cleaners: It contains a higher concentration of acid and the hydronium ions present in acid reacts with clogging substance and releases heat. This heat will dissolve the substance and clears the blockage.

  10. Question 7. What Is The Home Remedies To Clear Clogged Drain?

    Answer :

    The home remedies to clear clogged drain is

    • Take half a cup of baking soda and pour down the drain, and then pour half a cup of vinegar. After 15 minutes, flush out the drain with hot water
    • Add equal parts of salt, vinegar and baking soda. After one hour pour hot water into it
    • Add half a cup of salt and equal amount of baking soda, sprinkle it into the drain and then flush it with hot water

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  12. Question 8. Explain What Is Angle Stop?

    Answer :

    Angle stop is a shutoff valve between the water supply pipe and the fixture it supplies. It is used to shut off water to a fixture in case of failure, repair or leakage.

  13. Question 9. Mention What Are Some Health And Safety Issues That Plumber Face?

    Answer :

    Some of the health and safety risk that plumber face are

    • Exposure to a hazardous substance like lead, sulfur dioxide, mould, carcinogenic substances
    • Exposure to flammable and combustible materials
    • Working in awkward positions may lead to musculoskeletal injuries
    • Lifting heavy or awkward objects
    • Risk of eye injury from flying particles
    • Burns from hot equipment’s like steam lines, hot water heater, etc.
    • Cut and bruises due to a sharp end of pipes
    • Risk of electric shock while digging under-ground water pipes

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  15. Question 10. What Pre-caution A Plumber Could Take For Health And Safety Purpose?

    Answer :

    Some of the health and safety risk that plumber face are

    • Exposure to a hazardous substance like lead, sulfur dioxide, mould, carcinogenic substances
    • Exposure to flammable and combustible materials
    • Working in awkward positions may lead to musculoskeletal injuries
    • Lifting heavy or awkward objects
    • Risk of eye injury from flying particles
    • Burns from hot equipment’s like steam lines, hot water heater, etc.
    • Cut and bruises due to a sharp end of pipes
    • Risk of electric shock while digging under-ground water pipes
  16. Question 11. Explain What Is The Common Reason For Sump Pump Failure?

    Answer :

    Sump pump is usually used in the basement area to remove the accumulated water during flood. Moreover, there are few reason it may stop working all of sudden.

    • Switching problem
    • Accumulation of excess debris, interfering with the switching
    • The pump can move inside the basin, and that may interfere with the switching mechanism

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  18. Question 12. Explain How You Can Fix A Leaky Pvc Water Pipe?

    Answer :

    • Drain the water out and make the leakage pipe dry
    • Now take a coupling, similar to the size of the pipe that is leaking
    • Now cut the coupling into half
    • Make sure that the half you going to use should have stop inside, as you have to slide the leakage pipe into it
    • Slather the inside of the patch with adhesive, make sure that you have enough of the adhesive on your patch, as that is the portion that going to connect with the leaked pipe.
    • Place the patch onto the pipe and slide it into place and keep it overnight to get dry

  19. Field Hygiene and Sanitation Interview Questions

  20. Question 13. How Can You Avoid Bathroom Plumbing Maintenance?

    Answer :

    To avoid bathroom plumbing maintenance you can use the following tips

    • Once a week flushes out the drainage pipes with hot water
    • Apply pipe shield to drain lines once each month to keep soap scum building up and causing clogs
    • To prevent further damage to the fixtures and faucets repair leaky faucets
    • Showers and tubs should be fitted with strainers that can catch hair and soap chips
    • Use vinegar to remove mineral deposit in your shower head, by placing a vinegar in a plastic bag and leave it over the shower head overnight. Take only 1 cup of vinegar.
    • Throw the waste in wastebasket like tissue paper, cotton ball, etc.
  21. Question 14. Explain What Is Pipe Dope?

    Answer :

    A pipe dope is a pipe joint that is used to create a watertight seal.

  22. Question 15. Explain What Is Eductor?

    Answer :

    Eductor is a device that utilizes a nozzle and throat, fitted in a stream of water to build a partial vacuum to draw liquid or air into the stream; normally used to draw regeneration chemicals into an ion exchange water treatment system, like deionizer or softener.

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  24. Question 16. Connect Sump Pump Outflow To Septic?

    Answer :

    It is illegal to connect any rain or ground water to the sewer. IF, however, you do hookup – at the very least put a trap in the in the line to keep sewer gas out of the house.

  25. Question 17. Leak Somewhere In The Plumbing In My Shower/bath?

    Answer :

    I see this all the time and nine times out of ten its the grout or a bad pan under the shower. Before anything else I try to determine if the leak is constant or if it is periodic. If it is constant there is a good chance the leak is in the pressurized water lines. Usually the leak is periodic so I have a series of tests that I perform to track it down. Sometimes a quick visual inspection of the tile will show that the grout is shot and is the most likely cause of the leak but I will often complete the rest of my tests to be sure. What I do is first fill the tub half way and drain it.

    This will tell me if it’s in the drain pipe. For a shower with a lead or vinyl pan I block the drain and fill the base with water. This will tell me if the pan leaks. Then I remove the shower head and put a 1/2″ cap on the shower arm and turn on the pressure. This will tell me if there is a leak in the pipe between the shower valve and the shower arm. If no leak has shown up by then I tend to think the leak is water bleeding through the tile due to bad grouting or that water is escaping the shower and going down through flaws in the bathroom floor.

    I can check this by taping up a plastic dropcloth inside the shower covering all the tile work and having the customer use the shower normally for a day or two. If the leak has suddenly disappeared then we know it coming through the tile. A few cups of water on the floor will show a leak through bad tile or a cracked floor base.

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  27. Question 18. Can Clogged Vents Stop Up Drains?

    Answer :

    Yes and no. A toilet with no vent may not flush the contents out of the bowl, but any other drain will work without a vent. (NOTE: the code is that all fixtures shall be vented). Only twice in 15 years has the vents been the cause of a drain backup. In one case it was roofers who stuffed the old roofing material down the vents and the other was just a stray piece of wood. In both cases the material made its way down into the drain pipe and had to be removed. No amount of *vent cleaning* would have done any good.

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  29. Question 19. Leaking Bathtub Drain Right At The Drain Hole?

    Answer :

    It is replaced from the top, that is sitting in the tub. Hopefully you have *crosshairs* or a couple of little *nibs* inside the drain flange (the chrome part). That’s the part that unscrews. The tool is called a *pickle* – it has a fork at one end and crossed slots at the other. Or a *dumbell* which is tapered and has crossed slots at both ends. Or just use pliers and stick the handle end down into the drain, catch the cross hairs or nibs and unscrew. Clean off the old plumbers putty. Slide a new washer between the underside of the tub and the *shoe* (part with female threads) and put putty around the chrome flange and screw it back in.

  30. Question 20. Do Unused Drains Dry Up And Get Rough Inside?

    Answer :

    Yes, drain pipes do dry out and get real rough. Will it clear up with use? Maybe.

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  32. Question 21. How Do I Get A Snake Down A Tub Drain?

    Answer :

    To get a snake in the drain you take off the *overflow plate*. That’s the chrome thing on the tub wall with two screws. When you pull it out – two sections of the stopper mechanism will come with it. It’s hinged so it will bend through the hole. Chances are that hair caught on the end of this mechanism is clogging the drain- you might not even need to snake it. BTW – A snake will not go through the drain hole at the bottom of the tub.

  33. Question 22. When I Run The Cwm My Toilet Bubbles/overflows Or My Shower Overflows?

    Answer :

    The washing machine line could be connected to close to the “suds rinse zone”, meaning the washer waste ties into the waste or soil line of another fixture to close downstream from the problem fixture. What is happening is the water is rushing by the suds at a high velocity, pushing ahead of the suds. Because the fixture is the closest place of relief, the suds will come up into the fixture, even a toilet. The code requires that a washing machine, kitchen sink, shower, and dishwasher line be connected at least 5′ downstream from any fixture branch. This could be just one of many possibilities for the bubbling and backup.-Bill Dwight.

  34. Question 23. How Do I Know If I Have A Broken Water Line Outside My House?

    Answer :

    A broken water line out in the yard may include an excessively high water bill, puddles in your yard or the sound of running water when no faucets or appliances are using water. Blue Mountain can pinpoint the problem without needless trial and error destruction of working pipes. In many cases we can fix the problem right away and save you money.

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  36. Question 24. What Is The Most Common Reason For Sump Pump Failure?

    Answer :

    The leading cause for sump pump to failure is usually a switching problem. Sometimes the pump can move inside the basin. This movement causes the float that operates the switch to lodge against its side. Debris can also be a factor by interfering with the action of the pump switch. It is important to make sure that your pump switch and float arm assembly move freely.

    The main thing to remember about sump pumps is that they don’t last forever…even if you never use them. Internal part wear out and make them virtually useless when you need them most! Blue Mountain can test, maintain or replace any brand of sump pump. For flood-prone areas and homes that get water seeping in on a regular basis you may want to consider a sump pump back up system. There are even non-electric systems that work in the case of a power failure. Call Blue Mountain for more information.

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  38. Question 25. Sealing The W/c Tank To The Bowl?

    Answer :

    Get the best results by using the large donut gasket of the type that is square cut inside to match the shape of the nut on the bottom of the tank. Sealant will not help. Tighten the bolts down evenly to the point where the tank is snug on the bowl. Over tightening will break the bowl and/or tank.

  39. Question 26. High Pressure Makes My Toilet Run (with New Ballcock)?

    Answer :

    If your water pressure is so high that it leaks past a Fluidmaster 400A or another new ballcock (aka: “toilet fill valve”) – then you NEED a pressure reducing valve. Other water pipes, connectors, clothes washing machine hoses and your water heater could leak or break. Best to get a pressure regulator if your pressure to the house is more than 60 pounds (80 is code throughout most of the U.S.).

  40. Question 27. Toilet Leaks At Base In Moved Toilet Location Or New Floor Install?

    Answer :

    Is the top of the flange even (or close to even) with the finished floor? If it to low – then use two wax rings. One regular wax ring on the bottom and one (or more) with the plastic horn insert on top. ) I have seen leaks like you describe if the glued flange is not really glued in all the way. Take a look at that – if your floor and flange is flush. Sometimes you need to shim the toilet if the floor is uneven or the flange is to high.

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  42. Question 28. Explain Low Flush Toilet Problems?

    Answer :

    You might buy a better flushing toilet for your situation. Some air assisted toilet flush well. When the low gallonage gravity toilets first came out I replaced a couple of new Kohler Wellworth Lites with the Am.Std. air assist toilet with good results. That was then and this is now. Today most brands of gravity toilets flush well (including the redesigned Kohler Wellworth models). Power assisted toilets tend to be noisy and frankly, today I definitely do not recommend power assisted toilets.

    By the end of 1999 (most brands of U.S. made) gravity toilets manufactured were flushing fine. At the end of 2000 my guess is that over 85% of 1.6gpf toilets flushed well.

  43. Question 29. What Is Gas Hwt Height?

    Answer :

    Gas HWT have to be at least 18″ off the floor because combustible fumes *sink* and for air intake.

  44. Question 30. On Demand Hot Water System?

    Answer :

    The relative energy efficiency of these systems depends a lot on other factors such as the amount of heat loss from a more traditional storage tank system or the length of time hot water is stored before it is used. In practice they require a good deal more energy per volume of heated water than conventional systems and they cannot usually provide enough hot water for more than one fixture at a time. The traditional storage tank type of water heater can be quite efficient if the tank and the hot water pipes are properly insulated.

    The on-demand type heaters have their uses in the appropriate situation. I have found them practical and efficient in situations where hot water is used only occasionally such as in some shop situations or where a fixture is at a considerable distance from a traditional storage tank water heater, such as in a guest house or pool house. They can also be handy if you are adding hot water to a structure that has been cold-water-only and the cost or inconvenience of adding a complete hot water piping system will be prohibitive.

  45. Question 31. If I Have Need Rooter Service, Do I Have To Call One Of Those National Rooter Chains?

    Answer :

    No. We would recommend that you call a qualified, trained and certified plumber. Why? The water pipes inside and outside your home can be very delicate. In an older home, pipes wear thin from the inside out making them appear sound but in fact are very brittle. An unqualified and unskilled rooter company could cause extensive damage to your pipes and your home.

    The highly trained and certified technicians at Blue Mountain will take the time to properly diagnose the problem and utilize the right tools and techniques to solve the problem. Should there be an issue of a broken pipe or other unforeseen problems after we begin the job, our expert plumbers can immediately take action. Can the other guys? We’re not sure…and we don’t recommend that you take a chance.

  46. Question 32. Is There Really A Difference Between Hard Water And Soft?

    Answer :

    Yes. In fact, the difference can be damaging to your home and your body. Maybe you have experienced damaged clothing from the laundry, excessive soap consumption, pipe scaling, faucet and fixture deterioration, skin problems, or undesirable tastes or odors from your water. If you have, then you have a water problem. Call Blue Mountain for expert advice on all kinds of water treatment systems.

  47. Question 33. Explain Conventional Water Heaters Vs. Tankless Water Heaters?

    Answer :

    Conventional water heaters are by far the most common type of water heater in the U.S. today. They range in size from 20 to 80 gallons (or larger) and are fueled by electricity, natural gas, propane, or oil. Called ‘storage’ units, these water heaters transfer heat from a burner or coil to water in an insulated tank. The down side to a conventional water heater is that energy is consumed even when no hot water is being used.

    Tankless water heaters do not contain a storage tank like conventional water heaters. A gas burner or electric element heats the water only when there is a demand for hot water. 

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  49. Question 34. Water Heater Maintenance?

    Answer :

    1. Turn off electric power or gas before doing anything. Damage will result if element comes on when tank is dry. Turn of water supplying HWT. Note that a time switch is NOT a safe place to turn off the electricity! Do it from the circuit breaker, or pull the fuse. 
    2. Drain the water heater (HWT). After HWT is drained, and hose is still attached, open and close the inlet valve a few times to help flush the sediment out. Do this ’till the water comes out clear. You may have to dismantle the valve, if there are large chunks of scale coming loose. 
    3. Remove the sacrificial anode, which looks like a plug in the top of the HWT. Inspect; it should be almost as long as the water heater. Replace if any portion of it is thinner than about 1/4″;. 
    4. With anode out, shine flashlight inside of tank to inspect for rust. If you see a lot of rust, it’s probably time to replace it…before it fails. Water heaters are normally glass- or ceramic-lined to prevent corrosion; this is also what the anode’s for. The heat of the water hastens corrosion, once it starts. 
    5. Open up the element access panels. Disconnect one wire from each of the elements. With a volt-ohm-meter, check to see that both elements are still functional (the resistance across the terminals should be ??? ohms, but if your meter peaks out with exceptionally high ohms, it’s time to replace the element).
  50. Question 35. What Is Moen Faucet Repair?

    Answer :

    Moen faucets have cartridges that can be replaced. There is a clip (on top) that has to be pulled up and out before the cartridge can be replaced. Often it seems stuck as if it will not come out. Some replacement cartridges provide a plastic square to turn the cartridge in the valve body 1/4 turn. This breaks it free from the valve grease that it is stuck in. If, after replacing the unit ,the hot and cold are reversed, re-install with the cartridge turned 180 degrees.