How to Fix a Leaking Supply Line
Supply lines are the flexible hoses that connect your shutoff valves to faucets, toilets, and appliances. They're under constant water pressure 24/7, and when they fail, the results can be catastrophic — a burst washing machine hose can dump hundreds of gallons per hour onto your floor. The good news is that supply lines are cheap, easy to replace, and the single best preventive plumbing upgrade you can do in your home. If your supply lines are more than five years old, don't wait for a leak — replace them now.
Time Required
10-20 minutes per line
Difficulty
Easy
When to Call a Pro
Corroded shutoff valve or frozen connections
Step-by-Step: Replacing a Supply Line
Turn off the shutoff valve
Close the shutoff valve by turning the handle clockwise (gate or globe valve) or perpendicular to the pipe (quarter-turn ball valve). Open the faucet above to release pressure and drain residual water. Place a small bucket or towel beneath the connection — there will be water trapped in the line.
Inspect the supply line and connections
Before removing anything, identify where the leak is coming from. Check the connection at the shutoff valve, the connection at the fixture (faucet or toilet fill valve), and the hose itself. Look for bulging in rubber hoses (a sign of impending failure), green corrosion on brass fittings, and moisture or mineral deposits that indicate a slow leak. Sometimes the issue is a loose connection rather than a failed hose.
Disconnect the old supply line
Use an adjustable wrench to unscrew the supply line nut from the shutoff valve — turn counter-clockwise. Then disconnect the top end from the faucet or toilet. For faucet connections in tight spaces behind the sink basin, a basin wrench makes this job dramatically easier. Tilt the hose into your bucket to drain it completely.
Install the new braided stainless steel supply line
Measure the distance between the shutoff valve and the fixture connection — buy a line that's slightly longer to allow a gentle curve (never a kink). Make sure the rubber washers are seated inside both nuts. Hand-tighten both connections, then use a wrench for an additional quarter turn. Do not over-tighten — this is the most common installation mistake and can crack the plastic threads on toilet fill valves.
Test for leaks
Turn the shutoff valve on slowly — a sudden pressure surge can stress the new connections. Wrap dry paper towels around both connection points and wait 5 minutes. Check the towels carefully for any dampness. Also run the faucet at full pressure and recheck while the line is under maximum flow. Inspect again the next day to catch very slow seepage.
Supply Line Types and Lifespan
- Plain rubber hose (black): The cheapest and most failure-prone. Lifespan of 3-5 years. These should be replaced immediately if found anywhere in your home — they are the number one cause of catastrophic supply line failures.
- Reinforced rubber hose: Slightly better than plain rubber, with a braided fabric reinforcement layer. Still degrades and should be replaced every 5 years.
- Braided stainless steel: The standard recommended by plumbers. A rubber inner core is protected by a woven stainless steel sheath that prevents bulging and bursting. Replace every 8-10 years. Cost: $5-12 each.
- Braided stainless steel with auto-shutoff: Premium lines with a built-in mechanism that detects a burst and automatically stops water flow. Ideal for washing machines and any fixture in a second-story or unattended location. Cost: $15-30 each.
- Rigid chrome supply tubes: Found in older homes. They last a long time but are harder to install and more prone to developing leaks at the compression fitting if disturbed.
Washing Machine Hoses: The Hidden Danger
- Why they're dangerous: Washing machine hoses are under full house water pressure 24/7, even when the machine isn't running. A burst hose can release 500+ gallons per hour, causing tens of thousands of dollars in water damage.
- Warning signs: Bulging, blistering, or soft spots on the hose. Rust or discoloration at the connection points. Any visible cracking or fraying. Moisture or stains on the wall behind the machine.
- Best practice: Replace both hot and cold washing machine hoses with braided stainless steel every 5 years. Turn off the supply valves when leaving for vacation. Consider installing an auto-shutoff valve or water leak detector.
- Insurance factor: Washing machine hose failures are one of the top homeowners insurance claims. Some insurers offer premium discounts for braided stainless steel hoses and auto-shutoff valves.
Pro Tips
- •Write the installation date on the supply line: Use a permanent marker to write the date on each new supply line. This makes it easy to know when they're due for replacement — no guessing.
- •Never reuse old rubber washers: The rubber washers inside the supply line nuts compress permanently over time. If you're reconnecting a line, always use a fresh washer. They cost pennies at any hardware store.
- •Don't kink the supply line: A sharp bend weakens the hose and can crack the inner tube. If the line is too long, let it curve gently — never fold it back on itself or force it into a tight space.
- •Replace all supply lines at once: If one supply line is old enough to leak, the others are the same age. Replace every supply line in the house in one session — it takes about two hours for a typical home and costs under $50 in parts.
Frequently Asked Questions
How often should supply lines be replaced?
Replace rubber supply hoses every 5 years and braided stainless steel lines every 8-10 years, even if they look fine. Washing machine hoses are the most critical — a burst hose can release 500+ gallons per hour. Many insurance companies recommend replacing them every 3-5 years.
Are braided stainless steel supply lines better than rubber?
Yes. Braided stainless steel lines resist bursting far better than rubber hoses and typically last twice as long. They cost only a few dollars more and are the recommended standard for all supply line connections. Always replace a rubber hose with a braided stainless steel one.
Why is my supply line leaking at the connection but not the hose?
The rubber washer inside the supply line nut is likely compressed, cracked, or missing. Remove the line, check the washer, and replace it. Also inspect the threads on the shutoff valve — if they are corroded or damaged, the valve itself may need replacement.