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Garbage disposal is leaking underneath

Water under the sink is unsettling, but most disposal leaks come from a seal or a loose connection you can see — often a quick, inexpensive reseal rather than a dead unit.

tuneWhat are you noticing?
Select anything that matches and the checklist below reorders to fit. Not sure? Skip it.
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Start here

In Canada, start by pinning down WHERE the water shows up. Dry the whole unit and the cabinet, plug the sink, fill it, then release it and watch: water appearing at the TOP around the flange points to the most common cause — dried-out plumber's putty or a loosened mount. It is usually a straightforward reseal-and-tighten. Cut power to the disposal at the wall switch or breaker before you reach underneath, and never put a hand inside.

Ranked from real-world failure data. The order updates as you select what you’re noticing above.

Likely causes, in the order to check them

Showing the typical order
Beginner-friendly Doable, with care Safety-critical Call a pro

visibilityHow to find where it's leaking

warning Cut the power before you reach underneathA disposal leak is a water problem, but the unit and its outlet are wired for 120 V and sit right in the puddle. Before you put your hands or tools under the sink, switch the disposal off at the wall and, to be safe, shut off its breaker — and never put a hand inside the disposal itself. If water has already reached the outlet or you smell anything hot or electrical, stop and treat it as an electrical emergency instead of a leak.
  1. Switch the disposal OFF at the wall switch and, if you will be reaching underneath, shut off its breaker. The leak is water, but the disposal shares the cabinet with 120 V wiring — treat power and water as separate problems and kill the power first.
  2. Dry the whole unit and the cabinet floor with paper towel so any new water is obvious. Lay a fresh sheet of paper towel under the unit to catch the first drip.
  3. Plug the sink, fill it part-way, then pull the plug and watch the TOP flange as it drains. Water there points to a failed flange seal or a loose mount — the most common cause.
  4. Now run the dishwasher (if it drains through the disposal) and run water down the drain, watching the SIDE hose clamp and the discharge connection. Water at those joints points to a hose/clamp or gasket leak.
  5. If the top and all the connections stay dry but water still forms at the BOTTOM of the canister, the internal seals have worn through (or the body is cracked) — that is an end-of-life replacement, not a reseal.
buildflashlightbuildpaper-towel schedule10 min

handymanHow to fix it

With the power off, support and drop the unit off its mount, scrape off the old dried putty at the sink flange, lay a fresh rope of plumber's putty under the flange, reset and retighten the mounting ring evenly, then run water and check the top stays dry.

  1. Switch the disposal off at the wall and shut off its breaker. Place a bucket and towels underneath — you will have some standing water in the unit.
  2. Support the unit with one hand and turn its mounting ring to release it, then lower it clear. Disconnect the discharge and dishwasher lines if they are in the way.
  3. Scrape the old, hardened plumber's putty off the sink flange and the sink opening until the metal is clean and dry.
  4. Roll a fresh rope of plumber's putty, press it under the lip of the flange, seat the flange into the sink, and tighten the mounting ring evenly all the way around so the flange pulls down flat.
  5. Remount the disposal, reconnect the drain and dishwasher lines, restore power, run water, and watch the top flange for a full minute to confirm it is dry.
schedule40 min savings$5–20
Plumber's puttyA standard tub of plumber's putty (not silicone) for bedding the sink flange
gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: homeowner may do this · PE: homeowner may do this · QC: homeowner may do this
Resealing the sink flange with plumber's putty is routine homeowner plumbing maintenance in every province.

handymanHow to fix it

With the power off, check the dishwasher drain hose where it clamps to the disposal: retighten the clamp, and if the hose is cracked or perished, cut it back or replace it and fit a fresh clamp, then run the dishwasher and watch the connection stay dry.

  1. Switch the disposal off at the wall and shut off its breaker, then wipe the dishwasher hose connection dry so a new leak is easy to see.
  2. Snug the hose clamp with a screwdriver or nut driver — a slightly loose clamp is the usual culprit and often the whole fix.
  3. If the hose itself is cracked, hardened, or split at the end, trim the bad section back or replace the hose, then fit a fresh clamp firmly.
  4. Restore power, run a dishwasher cycle, and watch the connection through a drain to confirm it stays dry.
schedule20 min savings$5–25
Dishwasher drain hose & clampMatch the hose diameter to the disposal's dishwasher inlet; a stainless worm-gear clamp suits most
gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: homeowner may do this · PE: homeowner may do this · QC: homeowner may do this
Tightening or replacing the dishwasher drain hose and clamp is routine homeowner plumbing maintenance in every province.

handymanHow to fix it

With the power off, unbolt or unslip the discharge connection at the drain, replace the hardened rubber gasket with a matching new one, snug the connection back up, and run water to confirm the joint is dry.

  1. Switch the disposal off at the wall and shut off its breaker; put a small bucket under the discharge connection to catch drain water.
  2. Loosen the bolts or slip nut at the discharge elbow and separate the connection, noting how the gasket sits.
  3. Pull the old, hardened gasket and fit a matching new one, then reassemble the connection and snug it — firm, but do not overtighten and distort the gasket.
  4. Restore power, run water down the drain, and watch the joint for a minute to confirm it no longer weeps.
schedule25 min savings$3–15
Disposal discharge gasketMatch the gasket to your disposal's discharge outlet size (commonly the flanged rubber gasket in the manufacturer's discharge kit)
gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: homeowner may do this · PE: homeowner may do this · QC: homeowner may do this
Replacing the discharge drain gasket is routine homeowner plumbing maintenance in every province.

handymanHow to fix it

A disposal leaking from the bottom is replaced, not resealed: with power off at the breaker, disconnect the drain, dishwasher, and electrical supply, drop the old unit off its mount, then mount and connect a matching replacement and leak-test every joint and confirm the circuit before use.

  1. Shut off power to the disposal at the breaker and unplug it or disconnect its supply wires; confirm it is dead before touching any wire.
  2. Disconnect the discharge drain and the dishwasher hose, then support the unit, release the mounting ring, and lower the old disposal out.
  3. Mount and wire the matching replacement per its instructions, reconnect the drain and dishwasher lines, then run water and leak-test every joint before putting it back in service.
schedule90 min savings$120–350
Replacement garbage disposal unitMatch the horsepower and the mounting system (many use the same twist-lock ring) to your old unit
report Replacing the unit disconnects live wiring and the drainYou can replace a bottom-leaking disposal yourself, but doing it safely means shutting off the breaker, confirming the wiring is dead, disconnecting the drain, and leak-testing the reassembly. Because it touches both the electrical circuit and the plumbing, and in some provinces the electrical connection is restricted to a licensed electrician, this is a fair job to hand to a plumber or appliance tech. If any part of the wiring step makes you uneasy, stop here and route it up.
gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: permit + inspection required · PE: homeowner may do this · QC: licensed professionals only
Owner replacement of a plug-in disposal is generally permitted; a hardwired unit's electrical connection may be restricted — confirm the provincial rule.

verifiedWhy this one goes to a pro

A cracked disposal canister cannot be sealed — the unit has to be replaced, which means disconnecting live wiring and the drain and leak-testing the reassembly. This is work for a licensed plumber or appliance tech (and, where the province requires it, a licensed electrician for the connection). Confirm your local rule before anyone starts.

Your notes travel with the request — what you saw, what you ruled out, when it started — so the pro arrives with a head start instead of a mystery.

sort

Why the list is in this order

We don’t sort by likelihood alone. We sort the way a good, honest tradesperson thinks: rule out the free, safe, common causes first. That’s why the cheap checks outrank the expensive repairs — and why anything dangerous gets a hard stop instead of a pep talk. The order exists to save you money, not to sell you anything.