Supply problems include leaks, low pressure, and unexpected water bills. Finding and stopping leaks early limits damage.
Draft. Some reference links and cost figures are still being verified.
Water supply problems include hidden leaks, low pressure, and unexpected water bills. Finding and stopping a leak early limits damage to floors, walls, and framing.
| Question | Short answer |
|---|---|
| Where do leaks usually start? | Worn toilet flappers, faucet cartridges and washers, supply lines, and shutoff valves. Hidden leaks often sit in walls, under floors, or under slabs. |
| How do I check for a leak? | Read the water meter with no water running, then read it again after two hours. A change means water is moving through the system. A dye test checks toilets. |
| What does it cost? | 2026 cost guides put a typical leak repair at about $150 to $850, leak detection at about $150 to $500, main-line repairs at about $500 to $2,500, and slab leaks at about $630 to $4,400. |
| When do I need a pro? | Leaks inside walls or under floors, leaks on the main line, any slab leak, and any repair involving the water meter or pressure regulator. |
Water enters the home through a service line, usually past a meter, and branches to fixtures and appliances through supply lines. Shutoff valves at each fixture and a main shutoff let you isolate parts of the system. Many homes have a pressure-reducing valve on the main line that keeps pressure at or below 80 psi.
| Test | How to do it | What a result means |
|---|---|---|
| Meter test | Turn off all water, read the meter, wait two hours without using water, and read it again | A changed reading means water is leaking somewhere in the home or service line. EPA says leaks can waste nearly 10,000 gallons a year in the average home. |
| Toilet dye test | Add a few drops of food coloring to the tank, wait about 10 minutes without flushing, then check the bowl | Color in the bowl means the flapper or seal is leaking. Flush soon after to avoid staining. |
| Listen and look | Listen for running water when fixtures are off, and check faucets and under sinks for drips | Running water with nothing on points to a fixture or supply line. |
| Compare bills | Check whether water use rose without a change in household habits | A sudden rise often means a hidden leak. |
| Source | Symptoms | Fix | Who |
|---|---|---|---|
| Toilet flapper or fill valve | Running toilet, dye in bowl | Replace the flapper or fill valve. EPA says flappers wear out and should be replaced about every five years. | Homeowner |
| Faucet cartridge or washer | Dripping faucet | Replace the cartridge or washer | Homeowner |
| Supply line or shutoff valve | Drip at a connection, damp cabinet floor | Replace the flexible supply line or valve | Homeowner, or a plumber for hard-to-reach valves |
| Water heater or fitting | Puddle or drip at the heater | Tighten or replace a fitting; a leak from the tank body usually means replacement | Licensed plumber |
| Hidden wall or floor leak | Damp drywall, stains, mildew smell, rising bills | Locate the leak; repair often means opening the wall or floor | Licensed plumber |
| Main line or slab leak | Soggy yard, hot spots on the floor, high bills | Detection and repair or re-route; often needs a permit | Licensed plumber |
Water pressure matters for leaks because high pressure stresses fittings, valves, and appliances. The International Plumbing Code (Section 604.8) requires an approved pressure-reducing valve wherever static pressure inside a building is over 80 psi, with a strainer. Service lines to outside hose bibs are exempt. The International Residential Code uses the same 80 psi limit.
| Symptom | Possible cause | Next step |
|---|---|---|
| Water bill rises without more use | Hidden leak | Run the meter test. Call a plumber if the reading changes. |
| Damp drywall, soft floor, or mildew smell | Leak inside a wall or under a floor | Stop using the affected fixture if possible. Call a plumber promptly; repeated moisture leads to mold. |
| Water pooling near the meter or yard | Service line leak | Call the water utility and a licensed plumber. |
| Sudden drop in pressure at all fixtures | Main line problem or failed regulator | Check whether neighbors have the same problem. Call the utility and a plumber. |
| Task | Homeowner? | Notes |
|---|---|---|
| Replace a toilet flapper or fill valve | Yes | Usually a low-cost part; turn off the water first |
| Replace a faucet cartridge or washer | Yes | Turn off the supply valves and plug the drain |
| Replace a flexible supply line | Yes | Shut off the valve first; check that the new line is rated for the job |
| Replace a pressure regulator or work on the main line | No | Licensed plumber, and often a permit |
| Repair a slab leak or a leak inside a wall | No | Requires detection equipment and often opening finished surfaces |
| Job | Typical range | Notes |
|---|---|---|
| Leak repair (typical) | About $150 to $850 | Varies by access and parts |
| Leak detection | About $150 to $500 | Electronic or acoustic detection |
| Main water-line repair | About $500 to $2,500 | Permits and specialist equipment often required |
| Slab leak | About $630 to $4,400 | Depends on location and access |
These are estimates from 2026 cost guides. Confirm with local quotes before you budget.
| Condition | What changes | Advice |
|---|---|---|
| Freezing winters | Exposed pipes can split when they freeze | Insulate exposed pipes and know where the shutoff is before the cold arrives |
| High-pressure supply | Fittings and appliances wear faster | Check for a pressure-reducing valve and consider a gauge check |
| Hard water | Scale can narrow valves and fixtures, and affect regulators | Include valves and screens in regular checks |
EPA says leaks can waste nearly 10,000 gallons of water per year in the average home. Even a slow drip adds up, and a toilet leak is often the largest hidden loss.
Shutting off the main while you're away limits damage if a supply line bursts. Confirm the valve works before you need it, and mention it to anyone who checks on the house.
Replacing a part in the same place often does not. Repairs that move, add, or open supply lines, or that involve the main line or pressure regulator, often do. Check with your local building department.
| Term | Meaning |
|---|---|
| Static pressure | Water pressure when no water is flowing |
| Pressure-reducing valve | A valve that lowers high incoming pressure to a safe level |
| Shutoff valve (angle stop) | A valve under a fixture that isolates it from the supply |
| Slab leak | A leak in a supply line under a concrete slab |
| Service line | The pipe from the utility connection to the home |
Sources reviewed November 4, 2026. Independent professional review: pending. Confirm local rules with your building department.
| Service | When you need it | Typical cost (2026 guides) | DIY or pro | Permit usually? |
|---|---|---|---|---|
| Leak repair | Drip, damp floor, or rising bill | About $150 to $850 typical (Inch Calculator 2026) | Licensed plumber, or homeowner for simple parts | Usually not |
| Leak detection | Hidden leak with no visible source | About $150 to $500 (Alert Plumber, Inch Calculator) | Licensed plumber | No |
| Main water-line repair | Leak on the service or main line | About $500 to $2,500 | Licensed plumber | Usually yes |
| Slab leak repair | Leak under a concrete slab | About $630 to $4,400 (Inspect and Test) | Licensed plumber | Usually yes |
| Service | When you need it | Typical cost (2026 guides) | DIY or pro | Permit usually? |
|---|---|---|---|---|
| Meter test and bill check | Monthly or after a bill spike | Free; homeowner check | Homeowner | No |
| Toilet flapper replacement | Every five years, per EPA guidance | About $75 to $200 with a plumber; parts under $50 | Homeowner | No |
| Pressure check | Any sign of high or low pressure | Gauge check is a low-cost plumber visit; get a local quote | Licensed plumber | No |
| Service | When you need it | Typical cost (2026 guides) | DIY or pro | Permit usually? |
|---|---|---|---|---|
| Whole-house pressure-reducing valve | Static pressure above 80 psi | About $600 to $1,200 for a typical job; ranges from about $210 to $2,070 (guide estimates) | Licensed plumber | Usually yes |
| Replacement of supply lines or shutoff valves | Aging or failing supply lines | Get a local quote; parts are low cost | Homeowner for flexible lines; plumber for valves | Usually not for like-for-like |