If your kitchen sink is leaking, clogged or slow, the cause is nearly always under the sink. Empty the cabinet, run the water and wipe each joint with a dry paper towel to find the wet one. Loose slip nuts at the trap, a cracked supply line and a worn faucet connection cause most kitchen sink leaks.
This guide walks through each part under the sink, how to check it, which problems you can handle safely, and when to stop and call. A sink that is overflowing or leaking steadily should not wait for the weekend.
Before you open the cabinet
Safety checklist before you reach under the sink
- Unplug the garbage disposal or switch off its breaker. Never reach into the disposal, even when it looks off.
- Close the two shutoff valves under the sink by turning them clockwise. If they will not turn, close the main shutoff instead.
- Never mix drain cleaners or add bleach, ammonia or other chemicals to standing water. The fumes can be dangerous in a small kitchen.
- If the floor is wet, stay clear of outlets, power strips and appliance cords. Water and electricity together can injure you.
- Wipe up spills right away so you do not slip, and keep children and pets out of the kitchen until it is dry.
Start with a dry check
Clear the cabinet and put a bowl or towel at the bottom. You need to see which part is wet.
Under-sink checks that find the leak
- Wipe the supply lines, shutoff valves and faucet connections dry with a paper towel.
- Run cold water for a minute, then hot, and touch each joint with a fresh dry towel.
- Fill one bowl of the sink and release it while watching the trap and drain joints.
- Run the dishwasher and disposal, if you have them, and recheck the same joints.
- Look at the cabinet floor for swelling, stains or soft spots.
Where kitchen sinks leak and what it means
| Wet spot | Likely cause | Simple fix | Call when |
|---|---|---|---|
| Trap (curved pipe) | Loose slip nut or worn washer | Tighten by hand, replace washer | Pipe is cracked or corroded |
| Drain basket under the sink | Failed plumber's putty or gasket | Reseat or replace the basket | Sink is stainless or stone and hard to reach |
| Supply line to faucet | Cracked or loose braided line | Replace the line | Shutoff valve will not close |
| Base of faucet | Seals or mounting nuts | Tighten or replace seals | Faucet is cracked |
| Sprayer hose | Worn hose or fitting | Replace the hose | Leak is inside the faucet body |
| Dishwasher or disposal connection | Loose clamp or worn hose | Tighten or replace clamp | You are unsure about power or the disposal |
The trap and drain: leaks and slow draining
The P-trap holds a small plug of water that blocks sewer gas. It is also where grease, food scraps and coffee grounds collect. Slip nuts at each end can loosen as the pipe warms and cools.
A slow drain with a gurgle often means a partial clog. A sink that drains slowly even after the trap is clean may have a clog further down the line. Our drain cleaning crews clear kitchen lines and main drains with the right cable or jetting gear.
Safe trap cleaning
Put a bucket under the trap, unscrew the slip nuts by hand, empty the trap and rinse it. Reassemble with the washers seated flat. Run water and check for drips. If the nuts are corroded or the pipe is crushed, stop and call.
What to keep out of the drain
Grease, coffee grounds, eggshells, pasta and fibrous scraps all cause trouble. Hot water alone does not clear grease. It melts, moves down the line and sets again in a cooler pipe.
Other parts that fail under a kitchen sink
Supply lines
Braided lines last years but can crack or rust at the fittings. A line that bulges, frays or drips at the nut should be replaced, not tightened.
Shutoff valves
Old stop valves seize or leak when turned. If a valve does not close fully, a plumber should replace it before the faucet work starts.
Sprayer and hose
A side sprayer that drips or loses pressure usually has a worn hose, diverter or weight. The fix is a hose or sprayer replacement.
Dishwasher and disposal lines
These connect to the drain and the supply. A loose clamp or a clogged air gap shows up as water under the sink or in the dishwasher.
What to avoid
Common kitchen sink mistakes
- Using drain cleaner in a fully blocked sink, which sits in the pipe and burns skin and eyes.
- Overtightening plastic slip nuts and cracking them.
- Wrapping thread tape on compression fittings, which does not help them seal.
- Ignoring a small drip until the cabinet floor rots.
- Running the disposal to clear a clog without cutting power first.
- Reconnecting the dishwasher drain without a high loop.
When a kitchen sink problem needs a plumber
Call if the leak is steady, if the cabinet floor is soft, if shutoff valves will not close, if more than one fixture drains slowly, or if sewage smell comes up. These point to bigger repairs than a washer or nut.
A sink that backs up into the other side, or a tub that gurgles when the sink drains, may have a main line problem. Our sewer line cleaning service handles those. For a faucet that is worn out, see our faucet and sink repair page. Our line is open 24/7 for urgent leaks and backups.
What affects the cost of a kitchen sink repair
You get a clear price before work starts. These factors drive it.
What moves the price
- What failed: a trap washer, a supply line and a drain basket are different jobs.
- Access: a cramped cabinet with a disposal and dishwasher takes longer.
- Parts: shutoffs, supply lines and faucets vary widely.
- Clog depth: a trap clog is small, a main line clog is larger.
- Time of the call: nights, weekends and holidays are usually priced differently.
Rocky Hill homes and kitchen plumbing
Rocky Hill's housing stock was built mostly between the 1960s and the 1980s, with about 2,456 units added in the 1970s alone. About 39% of units in 2010 were multi-family, such as condos and apartments.
For you, that means kitchen plumbing in many homes is decades old, with original shutoffs and drain pipes. In a condo or apartment, a leak can reach the unit below, so shut off the water and tell your property manager as well as the plumber. MDC provides sewer service in town, so backups at the street are an MDC matter. Call (860) 278-7850 if you suspect that.
Source type: town planning document, census counts, utility contact page
Water pouring from under the sink?
Close the shutoff valves under the sink. If they will not close, turn off the main water valve. Keep away from outlets and cords in a wet cabinet, then call us.
Questions homeowners ask
Why is my kitchen sink leaking underneath?
The most common causes are a loose slip nut on the trap, a worn supply line, a failed drain basket seal or a leaking faucet connection. Dry every joint, run the water and touch each with a dry towel to find the wet one.
How do I unclog a kitchen sink safely?
Try a plunger with the other side blocked, then clean the trap by hand. Skip chemical cleaners on a fully blocked sink. If several fixtures are slow or the sink backs up again, the clog is further down and needs a cable or jetting.
Why does my kitchen sink gurgle?
Gurgling usually means air is moving through a partial blockage or the vent is struggling. A single slow sink often has a trap or branch clog. Gurgling across several fixtures points to the main line.
Can I replace a supply line myself?
Usually yes, if the shutoff valve closes fully. Turn it off, open the faucet, disconnect the old line and connect a new braided line. If the valve leaks or is stuck, call a plumber.
How do I know if the leak is from the sink or the faucet?
Dry everything, then run only the faucet and watch the supply lines and base. Then fill the sink and let it drain while you watch the trap. The wet point tells you which side is leaking.
Do you handle kitchen sink emergencies at night in Rocky Hill?
Yes. Our dispatch line answers 24/7, including nights, weekends and holidays. After-hours visits are priced differently, and we give you a clear price before work starts.
Do you serve Wethersfield and Cromwell for sink repairs?
We serve Rocky Hill and nearby towns, including Wethersfield and Cromwell. Call with the address and what is leaking, and we will book the next available plumber.
Call the 24/7 line, describe the problem, and we confirm what it will cost before any work starts.