Bunn Coffee Maker Leaking Water? 6 Fixes

Identify the Leak Location First

Bunn coffee makers use a unique hot water tank system that stays heated 24/7. This constant heat and pressure creates specific leak points different from other brands.

About 88% of Bunn leaks come from just three areas: spray head gasket, water tank seal, or brew funnel overflow. Most fixes take under 15 minutes.

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Quick Leak Check (3 Minutes)

Identify WHERE water comes from before trying fixes:

• ✅ From top during brewing - Spray head or funnel overflow (42% of leaks)
• ✅ From bottom constantly - Tank seal or valve (31% of leaks)
• ✅ From sides/back - Tank crack or tube connection (18% of leaks)
• ✅ From carafe area - Warmer plate condensation, not true leak (9%)

Pro Tip: Place paper towels around base and brew a full pot. Where towels get wet tells you leak source.

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Fix 1: Clean Spray Head and Gasket (Works 42% of Time)

Why This First: Coffee oils and mineral deposits prevent spray head from sealing properly. Water escapes around edges instead of through spray holes.

Symptoms:

• Water drips from top during brewing
• Spray head covered in brown residue
• Coffee grounds in water around machine
• Leak worse after not descaling for months
• Grounds overflow from brew funnel

How to Fix:

1. Remove Spray Head: Twist counterclockwise and pull straight down
2. Remove Gasket: Small rubber ring inside spray head assembly
3. Inspect Gasket: Look for cracks, hardening, or deformation
4. Soak in Vinegar: Both parts in white vinegar for 15 minutes
5. Scrub Spray Holes: Use toothpick to clear each hole completely
6. Clean Gasket Groove: Cotton swab removes coffee oil buildup
7. Rinse Thoroughly: Clear water until vinegar smell gone
8. Reassemble: Gasket seats in groove, spray head twists clockwise tight
9. Test Brew: Run full pot and check for leaks

Time: 12-15 minutes
Cost: Free (or $4 for replacement gasket)
Success Rate: 42%
Difficulty: Easy

⚠️ Model Notes:

• Speed Brew Classic: Spray head has 6 holes, check all clear
• Velocity Brew: Gasket slightly larger, not interchangeable with older models
• Phase Brew/NHS: Two gaskets (top and bottom), check both

💡 Replacement: Bunn spray head gaskets available at bunn.com (part #04213.0000) or Amazon. Replace every 12-18 months with hard water.

If This Doesn't Work: Try Fix 2 - check brew funnel overflow

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Fix 2: Prevent Brew Funnel Overflow (Works 23% of Time)

Why This Helps: Bunn's fast brewing floods funnel if filter clogs or grounds too fine. Water overflows sides instead of through coffee.

Symptoms:

• Water overflows funnel during brewing
• Grounds spill over filter edges
• Leak only happens during brew cycle
• Using fine grind coffee or cheap filters
• Problem started after changing coffee brand

How to Fix:

1. Use Quality Filters: Bunn or Melitta brand, basket-style
2. Check Grind Size: Should be medium (like coarse sand)
3. Reduce Coffee Amount: Max 10 tablespoons for 10-cup pot
4. Don't Pack Grounds: Loose coffee allows water flow
5. Center Filter: Must sit flat against funnel walls
6. Clean Funnel Holes: Bottom has small drain holes, keep clear
7. Pre-Wet Filter: Run water through empty filter 5 seconds first
8. Test with Half Pot: If no overflow, coffee amount or grind was issue

Time: 5 minutes
Cost: $4-6 (quality filters)
Success Rate: 23%
Difficulty: Easy

⚠️ Coffee Grind Guide:

• Too Fine: Espresso, Turkish (clogs filter, overflows)
• Just Right: Drip, medium grind (flows perfectly)
• Too Coarse: French press, percolator (weak coffee, but won't overflow)

💡 Filter Tip: Bunn recommends their own filters (BCF series) because basket shape matches funnel exactly. Generic flat-bottom filters can cause overflow.

If This Doesn't Work: Try Fix 3 - inspect water tank seal

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Fix 3: Replace Water Tank Seal (Works 18% of Time)

Why This Helps: Rubber seal around internal water tank degrades from constant heat. Leaks water slowly from bottom or sides.

Symptoms:

• Constant drip even when not brewing
• Water pools under machine after sitting overnight
• Small puddle appears daily
• Machine 3+ years old
• Water comes from center bottom area

How to Fix:

1. Unplug Machine: CRITICAL - hot water tank under pressure
2. Empty Tank: Remove spray head, pour pitcher of water through to flush
3. Wait 30 Minutes: Tank must cool below boiling
4. Flip Upside Down: Place on towel
5. Remove Bottom Plate: 4-6 screws, keep track of screw locations
6. Locate Tank: Large metal cylinder in center
7. Find Seal: Rubber gasket where tank meets bottom plate
8. Remove Old Seal: Carefully pry out with flathead screwdriver
9. Clean Groove: Remove mineral deposits and old gasket residue
10. Install New Seal: Press firmly into groove all around
11. Reassemble: Bottom plate and screws
12. Fill and Test: Plug in, fill tank, let heat 15 minutes, check for leaks

Time: 30-40 minutes (including cool-down)
Cost: $8-15 (replacement seal kit)
Success Rate: 18%
Difficulty: Moderate (requires screwdriver, comfort disassembling)

⚠️ Safety Warning: Water tank holds near-boiling water under pressure. ALWAYS unplug and wait 30+ minutes before opening. Serious burn risk if rushed.

💡 Where to Buy: Bunn tank seal kit (part #28086.0000) at bunn.com or Amazon. Some kits include multiple gaskets for different models.

If This Doesn't Work: Try Fix 4 - check internal tubes

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Fix 4: Inspect Internal Water Tubes (Works 4% of Time)

Why This Helps: Silicone tubes connecting tank to spray head can crack, loosen, or develop pinholes from age and heat.

Symptoms:

• Water drips from back or sides (not front)
• Leak visible inside when lid removed
• Hissing sound during heating cycle
• Steam escaping from unusual places
• Machine over 5 years old

How to Fix:

1. Unplug and Cool: Wait 30+ minutes
2. Remove Top Lid: Usually hinged or has screws
3. Locate Tubes: Clear silicone tubes running from tank to spray head
4. Check Connections: Ensure tubes firmly attached at both ends
5. Inspect for Cracks: Look for splits, especially near hot areas
6. Test Clamps: Small metal clamps should be tight
7. Replace Damaged Tubes: Measure diameter and length, buy from Bunn
8. Reseat Loose Connections: Push tubes fully onto barb fittings
9. Tighten Clamps: Use pliers to close clamps more firmly
10. Test: Fill machine, heat, and watch internal tubes for leaks

Time: 25-35 minutes
Cost: $5-10 (silicone tubing from hardware store or Bunn parts)
Success Rate: 4%
Difficulty: Moderate to Advanced

⚠️ Tube Specs: 5/16" inner diameter food-grade silicone tubing. Must handle 200°F+ temperatures. Don't use vinyl or rubber - will melt.

If This Doesn't Work: Try Fix 5 - check hot water tank valve

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Fix 5: Replace Hot Water Tank Valve (Works 1% of Time)

When It's the Valve: Constant dripping from bottom, even when empty. Valve at base of hot water tank lets water through slowly.

This Is Rare: Only 1-2% of leaks. Usually requires replacement because valve corrosion can't be cleaned effectively.

Cost vs Replace Decision:

• Valve Replacement: $15-25 (part) + $50-80 (professional install) = $65-105
• New Bunn Speed Brew: $120-180
• New Bunn Velocity Brew: $150-220

Recommendation: If machine is 5+ years old and valve failed, consider replacement. If under 3 years old and high-end model, valve replacement worth it.

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Fix 6: Check Warmer Plate "Leak" (Not Really a Leak)

The Confusion: Many people see water under Bunn and assume leak. Often it's condensation from hot warmer plate, not machine leak.

How to Tell Difference:

1. Wipe machine and area completely dry
2. Place paper towels under entire machine
3. Brew full pot and wait 30 minutes
4. Check paper towels

If Water on Towels:

• Around edges only: Carafe not seated properly, steam condensing
• Under center: Real leak, use Fixes 1-5
• Very small amount: Normal condensation from 24/7 heating

Not a Leak If:

• Water only appears after brewing
• Disappears within hour
• Less than 1 teaspoon total
• No dripping, just moisture

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When to Replace vs Repair

Replace Machine If:

• Tank cracked (not repairable)
• Multiple leak points
• Over 7 years old with heavy use
• Repair cost over $80
• Other issues beyond leak (won't heat, won't brew)

Repair Worth It If:

• Single leak point (spray head, gasket, tube)
• Machine under 3 years old
• High-end model (Velocity Brew, thermal carafe)
• Otherwise works perfectly

⚠️ Bunn Warranty: Most models have 2-year limited warranty. Check at bunn.com or call 1-800-637-8606 before paying for repairs.

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Prevent Future Leaks

Bunn's 24/7 hot water tank requires different maintenance than other coffee makers:

• 🔧 Every 3 Months: Descale with Bunn descaling powder (vinegar can damage tank)
• 🔧 Every 6 Months: Remove and clean spray head thoroughly
• 🔧 Yearly: Replace spray head gasket ($4 preventive vs $50 repair later)
• 🔧 Check Weekly: Look for small drips before they become floods
• 🔧 Use Filtered Water: Extends seal and gasket life by reducing mineral deposits
• 🔧 Don't Move Often: Internal tubes and connections loosen with movement

Pro Tip: Bunn's always-hot tank creates more mineral buildup than on-demand heaters. Descaling every 3 months (not 6) prevents 80% of leaks.

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FAQ

Why does my Bunn leak only sometimes?

Intermittent leaks usually mean spray head gasket is worn but not completely failed. Leaks when water pressure highest (fresh full tank) but seals when pressure drops (tank half empty). Replace gasket before it fails completely.

Is it normal for Bunn to leak a few drops?

No. Bunns shouldn't leak at all. Even small drips indicate gasket wear or loose connection. Address now before it worsens. Many "sudden" floods start as small drips ignored for weeks.

Can I use the Bunn if it's leaking a little?

Short term yes, but don't ignore it. Place towel underneath and fix within a week. Leaks worsen quickly. Water damage to counters and electrical components costs far more than $4 gasket replacement.

How often should I replace the spray head gasket?

Every 12-18 months with daily use and hard water. Every 24 months with soft water or filtered water. Gaskets cost $4, water damage and mold cost hundreds. Preventive replacement is smart.

Does the constant heating cause more leaks?

Yes and no. Bunn's always-hot tank creates pressure and mineral buildup faster, but design accounts for this. Properly maintained Bunns last 10+ years. Skip descaling and you'll have leaks by year 3.

Why is water leaking from the back of my Bunn?

Back leaks indicate internal tube connection problem or tank seal failure. Requires opening machine to access. If machine over 5 years old, weigh repair cost against replacement (new Speed Brew ~$140).