Basic Plumbing Repairs for Building Maintenance
Clear sink and toilet clogs, stop running toilets, fix dripping faucets, shut off water and know when a job needs a licensed plumber.
Table of contents
More maintenance calls start in restrooms than anywhere else. Most of them are simple: a clogged sink, a toilet that runs all day, or a faucet that drips. You can fix these yourself with a few hand tools. A running toilet can waste about 200 gallons a day, so quick fixes save real money. Your job is to solve the everyday problems cleanly and to recognize the bigger ones. Work inside walls, new piping, and sewer lines often belong to a licensed plumber, and local rules decide what you can do.
What You Will Be Able to Do
- Find and use shutoff valves
- Clear a clogged sink and toilet
- Repair a running toilet
- Identify a faucet type and fix a drip
- Tell when a problem is bigger than one fixture
Before You Start
Find the water shutoff first. Most sinks and toilets have stop valves below them. If a stop will not close, find the zone or main valve. Old valves sometimes leak after you turn them, so open and close them gently. Have a bucket, towels, and a wet floor sign ready. Restrooms are shared spaces, so put up a sign and post how long the room will be closed.
Wear gloves and eye protection, and wash up after working with any drain. Treat all drain water as dirty.
Clearing a Sink
- Remove the stopper or strainer, and pull out hair and debris.
- Block the overflow with a wet rag if there is one.
- Add 2 to 3 inches of water, and use a cup plunger with a flat bottom.
- Plunge firmly 15 to 20 times.
- If that does not work, put a bucket under the trap, loosen the slip nuts, and pull the trap off. Clear it.
- Reassemble it hand tight, then give it about a quarter turn with pliers. Run water and check for leaks.
- If the clog is farther in, feed a hand auger into the drain at the wall. Turn it clockwise. When you feel resistance, keep turning, then pull back to retrieve what you caught.
Avoid chemical drain openers. They rarely work on a full clog, they can damage parts, and they create a hazard for you or for the next person who opens the line.
Clearing a Toilet
- Use a flange plunger, the kind with a rubber lip that seals in the drain.
- Make sure there is enough water to cover the cup.
- Push down slowly first to remove air, then plunge firmly 15 to 20 times.
- If that fails, use a closet auger. Its sleeve protects the bowl from scratches.
If the water is rising, lift the tank lid and press the flapper closed, or turn off the stop.
If several fixtures back up at once, or if a floor drain overflows when you flush, the problem is probably in the main line. A hand tool will not solve that. Close off the restroom and call a plumber.
Running Toilets
The flapper is the first thing to check, since it is the most common cause.
| What you see | Likely cause | Fix |
|---|---|---|
| Water stops when you press the flapper | Flapper is not sealing | Replace the flapper |
| Water flows into the overflow tube | Fill valve or high water level | Lower the level or replace the fill valve |
| Refills often, with no visible cause | Slow flapper leak | Dye test, then replace the flapper |
| Flapper is new and it still runs | Worn flush valve seat | Replace the flush valve |
Replacing a Flapper
- Turn off the stop, and flush to empty the tank.
- Unhook the chain and pull the old flapper off.
- Take the old part with you to match it. Sizes and styles differ.
- Install the new one and leave a little slack in the chain.
- Turn on the water and test.
Replacing a Fill Valve
- Turn off the water, flush, and sponge out the tank.
- Disconnect the supply line.
- Remove the locknut under the tank and lift out the valve.
- Install the new one following the instructions.
- Set the water level about 1 inch below the top of the overflow tube, or at the mark.
- Reconnect the supply line and test.
Flush valve replacement means taking the tank off the bowl. Tighten the tank bolts a little at a time from side to side, so that you do not crack the china.
Commercial Flush Valves
Many commercial restrooms use flushometers, with no tank. If a unit runs on or will not shut off, the diaphragm or piston inside is often worn or clogged. Turn off the control stop on the side first, open the top, and clean or replace the inside parts from a kit. Sensor models also need fresh batteries. Check the model first, because parts are not universal.
Dripping Faucets
Turn off the water and put a towel in the basin to catch small parts. Plug the drain so that nothing falls in.
| Type | How to recognize it | Fix |
|---|---|---|
| Compression | Two handles that turn several times | Replace the washer, seat, or O-ring |
| Cartridge | One handle, or quarter-turn handles | Replace the cartridge |
| Ball | One handle over a rounded cap | Replace the seats, springs, and ball |
| Ceramic disc | One handle over a wide cylinder | Replace the disc assembly |
Steps for a cartridge:
- Remove the handle and the clip that holds the cartridge.
- Pull it straight out, with a puller if it sticks.
- Fit the new one the same way as the old one.
- Use silicone grease on O-rings.
- Turn the water on slowly and test both hot and cold.
Metering faucets, which shut off by themselves, and sensor faucets are common in commercial buildings. Their cartridges wear out or clog. Check aerators and screens first, since sediment is a common cause of low flow.
Water Pressure and Water Heaters
If flappers and fill valves fail often, measure the pressure with a gauge. Pressure over about 80 PSI wears out parts and causes leaks. A pressure-reducing valve is usually involved. Report it.
No hot water calls for a quick check before you call for help:
- Electric: Check the breaker. If it is on, a licensed person or qualified tech should look further.
- Gas: Check whether the pilot is lit or the unit shows a fault code. Follow the instructions on the unit, and only if you are authorized to do so.
If a relief valve is dripping, report it, and never plug it. If you smell gas, leave and call for help.
When to Call a Plumber
- Multiple fixtures backing up
- Sewer smells that will not go away
- Leaks inside walls or above ceilings
- Broken or corroded valves on main lines
- Any new piping, or a move of a fixture
- Any work on gas piping
Stop the water, contain the mess, and write down what you see.
Finishing Up
Test the repair twice. Wait a few minutes and check again for drips. Clean the area, remove your signs, and close the work order with the parts you used. If you see the same problem again and again, write that down as well.
Common Mistakes
| Mistake | What it costs |
|---|---|
| Starting before finding the shutoff | A flood |
| Overtightening plastic slip nuts | A cracked nut and a new leak |
| Buying the wrong flapper | A return trip |
| Using a cup plunger on a toilet | A poor seal and no result |
| Pouring chemicals on a full clog | A burn risk for you or the next person |
| Treating a main line clog as a toilet problem | Hours wasted while sewage backs up |
Check Your Understanding
1. A toilet runs constantly. What do you check first?
The flapper. Press it down. If the water stops, it is not sealing.
2. You plunge one toilet and a floor drain nearby starts to back up. What is going on?
The clog is likely in a main line. Close the restroom and call a plumber.
3. A flapper you replaced 2 months ago is already bad. What else should you check?
The water pressure. High pressure can wear parts early. Also check for chemical tablets in the tank, since those can eat rubber.
4. Water still drips from a two-handle faucet that turns several times. What is the likely fix?
It is a compression faucet. Replace the washer or seat.
Key Takeaways
- Find the shutoff before you start.
- Use a cup plunger on sinks and a flange plunger on toilets.
- Check the flapper first on a running toilet.
- Identify the faucet type, and bring the old part for a match.
- Multiple backups point to a main line problem, so call a plumber.