20 Common Plumbing Problems and How to Fix Them

Left alone, plumbing problems lead to water damage, higher bills and sometimes health risks. In San Jose and South Bay homes, older galvanized pipe, cast-iron drains, slab foundations and clay sewer laterals have their own common trouble spots. Knowing the usual problems helps you act in time, whether that means a simple repair or calling a licensed plumber.

Many problems share symptoms: low pressure, bad smells or discolored water. A running toilet seems minor but can leak thousands of gallons a year; a burst pipe can flood a room in minutes. For each of the 20 problems below, we cover the causes, the signs, the fixes, and whether it’s a DIY job.

1. Leaking Faucets

Drips usually come from a worn washer, a cracked O-ring, a worn cartridge or a corroded valve seat, from age, heavy use or hard-water scale. Look for constant moisture in the basin, stains around the fixture and a rising water bill. Left alone, the leak gets worse and can damage the cabinet below.

Solutions:

• Identify the faucet type (compression, cartridge, ball or ceramic disc) so you buy the right parts.
• Replace the worn washer, O-rings, cartridge or handle seal, with plumber’s grease on the O-rings.
• Clean or replace a corroded valve seat.
• Call a plumber if parts are seized or corroded, or the faucet is old enough that parts are hard to find. See why a faucet drips.

Faucet Part Failure vs. Water Waste Estimate

Whatever the part, the waste adds up: EPA WaterSense says a faucet dripping once a second can waste more than 3,000 gallons a year. The part is usually far cheaper than the water it wastes.

2. Clogged Drains

Hair, soap scum, food scraps and grease build up inside the pipe until the flow slows or stops, with standing water, gurgling and odors. The symptoms show where the clog sits: slow at one drain usually means debris just below the stopper; standing water, a clog in the trap or branch line; several slow drains at once, the main line.

Solutions:

• Use a plunger to dislodge minor clogs.
• Pour very hot tap water (not boiling, which can soften PVC joints) with baking soda and vinegar for light organic buildup.
• Use a hand snake or auger for deeper clogs.
• Remove and clean the P-trap if the blockage is close to the sink.
• Skip chemical drain cleaners; they damage pipes and are dangerous if the drain won’t clear.
• Call a plumber if several drains are slow, a sign of a main line blockage. CPI’s drain cleaning is typically $250–$600. See how to unclog a drain.

3. Low Water Pressure

If only one fixture is weak, the usual culprits are a clogged aerator, a scaled showerhead or a worn cartridge. If the whole house is weak, look at a partly closed shutoff valve, a failing pressure regulator, a hidden leak, or galvanized pipe narrowed by corrosion. Most homes run at 40 to 80 psi; a hose-bib gauge tells you where yours is.

Solutions:

• Clean blocked aerators and showerheads.
• Make sure the main and fixture shutoff valves are fully open.
• Check for leaks under sinks and in walls.
• Flush the water heater if only the hot water is weak.
• Replace corroded or narrowed galvanized pipe in older homes.
• Call a plumber if several fixtures are weak and there’s no local blockage. See how repiping improves water pressure.

4. Running Toilet

According to EPA WaterSense, a worn flapper can make a toilet flush on its own or silently leak thousands of gallons a year. Other causes are a float set too high, a fill valve that doesn’t shut off, or a flush chain that’s too short or tangled. Signs include a constant hiss, the tank refilling on its own, or having to jiggle the handle. To test, put a few drops of food coloring in the tank: color in the bowl after 10 minutes means a leak.

Solutions:

• Replace a worn or misaligned flapper.
• Adjust the float so the water stops below the top of the overflow tube.
• Replace a fill valve that keeps running.
• Shorten or untangle the flush chain so the flapper seats.
• Call a plumber if several parts have failed or the overflow tube is cracked.

DIY vs. Full Replacement

See toilet repair cost.

5. Burst Pipes

A burst pipe can damage walls, floors and even the foundation within minutes. Bursts come from corroded pipe, weak joints, high pressure or, on the South Bay’s rare frosty nights, freezing in attics, crawl spaces, garages and outdoor lines.

What to do right away:

1. Shut off the main water valve to stop the flow.
2. Turn off electricity to wet areas only if you can reach the panel without standing in water; otherwise stay out and call for help.
3. Open faucets to drain the remaining water and relieve pressure.
4. Remove standing water with towels, buckets or a wet/dry vacuum.
5. Photograph the damage for insurance.
6. Call a licensed plumber to repair the pipe and check for hidden damage.

A repair clamp or rubber patch can hold a visible split temporarily. A plumber then replaces the damaged section with code-approved pipe (PEX or copper for supply lines) and reroutes it if needed. Insulate exposed pipes so it doesn’t happen again. See emergency plumber cost.

6. Water Heater Issues

Common causes of water heater failure include sediment at the bottom of the tank, which makes the heater overwork; failed heating elements or thermostats; a faulty temperature and pressure relief valve; and, in gas heaters, a pilot or thermocouple problem. Signs your water heater needs repair include lukewarm water, hot water that runs out fast, popping or rumbling, rusty hot water from internal corrosion, and water pooling at the base.

Solutions:

• Flush the tank to remove sediment (see water heater maintenance tips).
• Relight the pilot following the instructions on the heater’s label.
• Have a technician replace the anode rod, heating elements, thermostats, thermocouple or relief valve; these involve electrical, gas or pressure parts.
• Consider replacement if the tank is leaking, corroded inside or near the end of its expected life.
• If you smell gas, leave the home and call 911 and PG&E from outside.

7. Dripping Shower Head

EPA WaterSense notes that a showerhead leaking 10 drips a minute wastes more than 500 gallons a year. Most drips come from the shower valve, where a worn cartridge, washer or O-ring or hardened scale keeps it from closing fully. Constant moisture also damages grout and encourages mold.

Solutions:

• Replace the worn washer, seals or cartridge in the shower valve.
• Wrap the showerhead threads with plumber’s tape so the connection doesn’t leak.
• Soak the showerhead in vinegar to dissolve scale.
• Replace the whole valve if it’s corroded inside; that usually means opening the wall, so it’s a plumber’s job.
• Call a plumber if it still drips after you replace the parts.

8. Sewer Line Backup

A sewer backup sends wastewater back up through drains and fixtures, a health risk and costly damage. It happens when the main sewer line is blocked or damaged. Common causes of sewer backup include grease, tree roots, flushed wipes and other non-flushable items, and cracked or collapsing clay pipe in older homes. In cities with combined sewers, heavy rain can overwhelm the system; elsewhere, rainwater and groundwater seeping into cracked laterals can add to the problem.

Early signs of a sewer backup include several drains gurgling at once, sewer odors near floor drains, and water rising in a tub or shower when you flush. Stop using water and call a plumber.

Solutions:

• A sewer camera inspection finds the blockage or damage (CPI: typically $300–$600).
• Hydro jetting clears roots, grease and debris from the line (CPI: typically $1,500–$2,500 for a main sewer line). See hydro jetting cost.
• Damaged or collapsed sections are repaired or replaced; see sewer line replacement cost.
• Keep wipes, grease and other non-flushables out of the drains.
• A backwater valve can stop sewage from flowing back into the house; it needs a permit.
• Work on the connection to the city sewer needs a licensed plumber and a permit.

Sewer Line vs. Drain Pipe

9. Slow Draining Sink

A slow sink is an early sign of a clog that will become a full blockage. In kitchens, grease, food scraps and soap are the usual causes; in bathrooms, hair, toothpaste and cosmetics collect just below the stopper.

Solutions:

• Remove and clean the drain stopper to clear surface buildup.
• Run very hot tap water, then baking soda and vinegar, for light buildup.
• Use a plunger or a hand snake to clear buildup in or past the trap.
• Remove and clean the P-trap (have a bucket and towels ready).
• Keep oil, grease and starchy food out of the kitchen sink.
• Call a plumber if several sinks are slow, a sign of a larger drain problem. See how to unclog a sink.

10. Water Discoloration

In older homes, rusty water typically comes from corroded galvanized or iron pipe. If only the hot water is discolored, the water heater is the likely source. Water main work can stir up sediment temporarily. Because discolored water can also carry contaminants, have it tested if it doesn’t clear.

What the color usually means:

• Brown or rusty: corroded pipe or sediment in an old water heater. Flush the heater and have the pipes inspected.
• Yellow: iron or manganese, more common with well water. Test for them and filter if needed.
• Reddish: heavy pipe rust or iron bacteria. Have the water lab-tested.
• Cloudy or milky: usually tiny air bubbles. If a glass clears from the bottom up within a few minutes, it’s air and harmless.
• Blue-green stains: copper corrosion, often from water chemistry. Have a plumber check the pipes.

Solutions: run the cold water for several minutes after water main work; flush the water heater if only the hot water is discolored; replace corroded galvanized pipe; consider whole-house filtration; and call your water supplier (San Jose Water or San Jose Municipal Water in most of the city) or a plumber if it persists.

11. Leaking Pipes

Leaking pipes cause hidden water damage, mold and weakened structure. In older homes, copper and galvanized pipe wear thin, especially with hard or aggressive water, and pinhole leaks form unseen until stains or musty smells appear. In newer homes, leaks often come from poor installation, high water pressure or thermal expansion stressing the joints. Common signs of leaking pipes include damp spots on walls or ceilings, lower pressure, puddles under sinks and an unexplained jump in the water bill. In South Bay slab homes, a leak under the floor can show up as a warm spot or the sound of running water; see slab leak signs.

Solutions:

• A repair clamp or epoxy putty can seal a small leak temporarily.
• Replace worn gaskets or loose fittings that seep.
• Check copper and galvanized lines for corrosion and replace damaged sections.
• Professional leak detection uses acoustic tools, moisture meters and thermal cameras to find leaks without opening walls (CPI: typically $150–$600 for an accessible leak).
• Call a plumber for leak detection, and consider repiping if leaks keep coming back. See how to detect water leaks.

12. Clogged Toilet

Toilet clogs usually come from too much paper, non-flushable items, or an older low-flow toilet that doesn’t flush with enough force. Most sit in the trap, the curved passage built into the toilet; deeper clogs need professional equipment. If it doesn’t drain after one flush, don’t flush again: you risk an overflow.

Solutions:

• Use a flange plunger with a tight seal and several firm pushes; it clears most clogs.
• Use a closet (toilet) auger for deeper blockages in the trap.
• Don’t flush wipes (even “flushable” ones), hygiene products or paper towels.
• Replace an old low-flow toilet that can’t clear waste with a modern, better-flushing model.
• Call a plumber if clogs keep coming back or other fixtures are affected, a sign of a line blockage.

13. Spiking Water Bill

A bill that jumps without a change in use usually means a hidden leak. EPA WaterSense estimates the average household’s leaks waste more than 9,300 gallons a year, and that about 9% of homes have leaks wasting 50 gallons or more a day. Running toilets, dripping faucets and cracked pipes are the usual sources; irrigation systems, water softeners and water heaters can also run without anyone noticing.

Solutions:

• Do a meter test: read the meter before and after two hours with no water in use. Any change means a leak.
• Check irrigation lines, valves and the water softener for continuous flow. Valley Water offers free Water Wise Outdoor Surveys that check irrigation systems, and rebate programs such as its Landscape Rebate Program.
• Replace old fixtures with WaterSense-labeled models.
• Call a plumber if you can’t find the source but use stays high.

Monthly Water Usage Tracker Template

Reading the meter at the same time each day for a week or two shows your normal use and makes a leak easy to spot. Many meters read in cubic feet rather than gallons (one cubic foot is about 7.48 gallons); just record the units your meter shows.

Subtract yesterday’s reading from today’s to get daily use. A day well above your usual, with nothing to explain it, is worth a meter test.

14. Frozen Pipes

Freezing water expands and can split copper, PVC or even PEX. Hard freezes are rare in San Jose, but outdoor pipes, backflow devices, hose bibs and sprinkler lines can freeze on frosty nights, especially in the foothills. Signs include frost on the pipe and no flow from a faucet on a freezing morning.

Solutions:

• Turn off the water to the frozen line and open the faucet to relieve pressure.
• Thaw it gently with a hair dryer or a space heater kept at a safe distance.
• Never use an open flame to thaw pipes; it’s a fire hazard.
• Insulate vulnerable pipes in attics, crawl spaces, garages and exterior walls.
• Call a plumber if the pipe has burst or you can’t reach it safely.

Before a cold snap: cover the backflow device, disconnect hoses, open cabinet doors under sinks on exterior walls and let a faucet drip on the coldest nights.

15. Bad Smells

A common source is a dry P-trap: the U-shaped pipe under every drain holds water that blocks sewer gas, and in a rarely used drain it evaporates. Other causes are rotting food in a disposal, biofilm in shower drains, a clogged or cracked vent, and a loose toilet seal.

Solutions:

• Run water in unused drains to refill the trap.
• Clean drain stoppers and overflow holes; use an enzyme cleaner for biofilm.
• Have a cracked or blocked vent pipe checked.
• Replace worn or missing trap seals and toilet wax rings.
• Call a plumber if smells persist or show up in several rooms.

Drain Odor Troubleshooting Chart

If smells get worse after rain or come from several drains, the cause is likely in the sewer line or venting.

16. Jammed Garbage

Food waste, fibrous scraps or a dropped object gets wedged between the spinning plate and the grinding ring, so the impellers can’t turn. A hum with no grinding is the classic sign; a jam can also trip the unit’s reset button or back up the sink. Eggshells, potato peels, bones and small utensils are common culprits.

Solutions:

• Turn off the switch and unplug the unit or switch off its breaker before touching it.
• Insert the hex key (usually ¼ inch) into the socket at the bottom center of the unit and work it back and forth to free the jam.
• Remove anything lodged with tongs or pliers, never your hand.
• Press the red reset button on the bottom, restore power and test with cold water running.
• Keep fibrous foods, bones and grease out.
• Replace the disposal if it keeps jamming or the motor fails.

17. Sump Pump

A sump pump keeps a basement or crawl space from flooding by pumping water out of a pit and away from the house; a float switch turns it on as the water rises. Few South Bay homes have one, but where installed, it matters in the rainy season. Problems show up in heavy rain or power outages, or from lack of maintenance: a stuck float switch, a clogged discharge line, a failed check valve or a worn motor.

Solutions:

• Test the float switch before the rainy season and a few times during it by pouring water into the pit.
• Clear the discharge pipe so water flows out freely and away from the foundation.
• Clean sediment and debris out of the pit.
• Add a battery backup for power outages.
• Replace an aging or noisy pump before it fails.
• Have a plumber handle motor or electrical problems and larger or backup systems.

18. Dirty Water

Persistent cloudy, brown or bad-tasting water is a real concern. Common causes are rust and sediment from corroded galvanized pipe, mineral deposits from an aging water heater, and, less often, bacteria or a cross-connection with a non-drinking source (one reason backflow devices are required). Iron and manganese mostly discolor water, but lead, bacteria and other contaminants can be health risks. If the problem affects both hot and cold water throughout the house, stop drinking it and have it tested.

Solutions:

• Use a test kit for iron, manganese, hardness or bacteria, and a certified lab for anything health-related.
• Install whole-house filtration if testing shows a problem.
• Call your water supplier or a plumber if every faucet is affected.

19. Bubbling Paint or Ceiling

Bubbling or peeling paint often means a hidden leak soaking the drywall, usually with a stain or musty smell. Common sources are leaking pipes between floors, a poorly sealed tub or shower drain, and condensation on uninsulated cold lines. Left alone, the moisture weakens drywall or plaster and grows mold.

Solutions:

• Find the source first with a moisture meter or thermal camera.
• Open the damaged drywall carefully to expose the leak.
• Repair the leaking joint or fitting.
• Dry the area completely before priming and painting.
• Call a plumber for hidden or multi-floor leaks and pipe replacement.

20. Leaking Hose Bib

Puddles under an outdoor spigot usually trace back to the hose bib. The most common cause is a worn washer or loose packing nut. A bib can also crack inside if it freezes with a hose attached, which can happen on the South Bay’s coldest nights. Watch for steady drips, moisture where the bib meets the wall, or mildew by the foundation; ignored, the leak can damage the foundation or crawl space.

Solutions:

• Tighten or replace the packing nut to stop leaks at the handle.
• Replace the worn washer or O-rings on the stem.
• Install a vacuum breaker (backflow preventer) so hose water can’t siphon back into the house.
• Replace a cracked or freeze-damaged bib.
• In colder spots, a frost-free hose bib prevents freeze damage.
• Call a plumber for work inside the wall or a hard-to-reach connection.

Hose Bib Issue and Solution Reference

How Professional Plumbing Services Solve Common Plumbing Issues

A licensed plumber fixes everyday problems quickly and uses diagnostic tools (sewer cameras, acoustic leak detection, pressure gauges) to find the cause of bigger ones. Preventive maintenance (pressure checks, water heater flushing, fixture inspections) keeps problems from coming back. CPI’s Gold Plumbing and Platinum membership plans include an annual plumbing inspection and water heater flush. Larger jobs like sewer line replacement and repiping are planned with permits and minimal disruption. For typical prices, see plumber cost in San Jose.

Safety First

• Know where your main water shutoff is.
• If you smell gas, leave and call 911 and PG&E from outside.
• Don’t use chemical drain cleaners on standing water.
• Leave gas, electrical, sewer and in-wall work to licensed professionals; much of it needs a permit in San Jose.

To stay ahead of problems, see plumbing safety tips, plumbing maintenance tips and the plumbing inspection checklist.

Plumbing Problems in San Jose Homes

• Older homes: galvanized pipe, cast-iron drains and clay laterals are behind many repeat problems.
• Slab foundations: hidden supply leaks under floors.
• Hard water: scale in faucets, showerheads and water heaters.

CPI Service fixes plumbing problems throughout San Jose and the South Bay. Request a free estimate or call (408) 978-3093.