Toilet Installation Guide
Step-by-step instructions for installing a new toilet or replacing an old one. Includes flange repair, wax ring installation, and leak prevention.
Estimated Time
2-3 hours
Tools Required
8 items
Materials Needed
7 items
Replacing a toilet is a manageable DIY project that most homeowners can complete in an afternoon. Whether you're upgrading to a more efficient model, fixing a cracked tank, or simply updating your bathroom's look, toilet installation requires basic plumbing skills and the right approach.
Modern toilets are more water-efficient than older models, often using just 1.28 gallons per flush compared to 3.5-7 gallons for older toilets. Replacing an old toilet can save thousands of gallons of water annually while improving performance.
The process involves removing your old toilet, preparing the flange and floor, installing a new wax ring, setting the new toilet, and connecting the water supply. With patience and attention to detail, you can achieve a professional-quality installation.
Safety Precautions
- Turn off the water supply before starting work
- Wear gloves when handling the old toilet and wax ring
- Use proper lifting techniques - toilets are heavy and awkward
- Protect your bathroom floor with cardboard or drop cloths
- Ventilate the area well, especially when working with old wax rings
- Have towels ready to mop up any residual water
- Don't overtighten bolts - this can crack the porcelain
Tools Required
- Adjustable wrench
- Screwdriver
- Hacksaw or PVC cutter
- Level
- Putty knife
- Bucket and rags
- Caulking gun
- Measuring tape
Materials Needed
- New toilet
- Wax ring with sleeve
- Toilet bolts and caps
- Water supply line
- Silicone caulk
- Shims (if needed)
- Flange repair kit (if needed)
Preparation
Measure Your Space
Measure from the wall (not baseboard) to the center of the toilet floor bolts. This is your "rough-in" measurement, typically 12 inches but sometimes 10 or 14 inches. Purchase a toilet that matches your rough-in measurement.
Choose Your Toilet
Select between a two-piece toilet (separate tank and bowl) or one-piece design. Two-piece toilets are easier to handle during installation. Consider WaterSense-certified models for water efficiency and round vs. elongated bowl based on your space.
Inspect the Flange
Before buying a new toilet, remove the old one and check the toilet flange condition. A damaged flange will need repair before installing the new toilet. Flange repair kits are available for most common problems.
Installation Steps
Remove the Old Toilet
Turn off the water supply valve behind the toilet. Flush the toilet to empty the tank, then use a sponge or towel to remove remaining water from both the tank and bowl.
Disconnect the water supply line from the bottom of the tank using an adjustable wrench. Place a bucket underneath to catch any remaining water.
Remove the caps covering the floor bolts at the base of the toilet. Use a wrench to remove the nuts - if they're corroded, apply penetrating oil or cut them with a hacksaw.
Rock the toilet gently side to side to break the wax ring seal, then lift straight up and away. Set it on cardboard to protect your floor.
Pro Tips:
- Have towels ready - there's always more water than you expect
- If the toilet won't budge, the wax ring may be stuck - apply more rocking motion
Warning:
- Toilets are heavier than they look - get help if needed
Clean and Inspect the Flange
Scrape away all old wax ring residue from the toilet flange using a putty knife. The flange must be completely clean for the new wax ring to seal properly.
Inspect the flange for cracks or damage. The flange should sit level with or slightly above the finished floor. If it's broken or below floor level, install a flange repair kit or extender ring.
Stuff a rag into the drain opening to prevent sewer gas from entering your home and to catch any debris. Remember to remove it before setting the new toilet!
Check that the floor around the flange is solid and level. Repair any soft spots or level uneven areas before proceeding.
Pro Tips:
- Take a photo of the flange for reference if you need to buy repair parts
- This is a good time to replace the flange bolts even if they look okay
Install New Flange Bolts and Wax Ring
Insert new closet bolts into the flange slots, positioning them equal distance from the wall and perpendicular to the wall. The bolts should be positioned so the toilet will sit properly centered.
Place the new wax ring over the flange opening. Most plumbers recommend wax rings with a plastic sleeve or horn that fits into the drain opening - these provide better seals than plain wax rings.
If your flange sits below floor level, use a double wax ring or an extra-thick wax ring. Never stack two regular wax rings.
Remove the rag from the drain opening now, before you forget!
Warning:
- Don't place the wax ring on the toilet base - it goes on the flange
- Work quickly once the wax ring is in place - wax can soften in warm rooms
Set the New Toilet
If installing a two-piece toilet, attach the tank to the bowl now while it's easier to handle. Follow the manufacturer's instructions for tank-to-bowl bolts and gaskets.
Carefully lower the toilet onto the flange, aligning the holes in the base with the closet bolts. The toilet should sit directly over the wax ring.
Once aligned, press down firmly with your full body weight, rocking slightly to compress the wax ring. The toilet base should sit flush against the floor with no gaps.
Thread washers and nuts onto the closet bolts and hand-tighten. Then use a wrench to tighten them alternately (a little on one side, then the other) until snug. Don't overtighten!
Pro Tips:
- Have a helper guide the bolts through the holes while you lower the toilet
- The toilet should feel solid and not rock when you sit on it
Warning:
- Overtightening the nuts can crack the porcelain base
- Don't lift the toilet back up once set - you'll break the wax ring seal
Connect Water Supply and Test
Connect a new flexible water supply line to the toilet tank's fill valve. Hand-tighten, then snug with a wrench - usually a quarter turn past hand-tight.
Turn on the water supply valve slowly and check for leaks at all connections. The tank should fill automatically.
Let the tank fill completely, then flush several times while checking around the base for any water seepage. Watch the water supply connection for leaks.
If no leaks appear, apply a thin bead of caulk around the base of the toilet where it meets the floor. Leave a small gap at the back for any future leaks to escape (this prevents hidden water damage).
Trim the closet bolts with a hacksaw so they're just above the nuts, then install the decorative caps.
Pro Tips:
- Wait 24 hours before applying caulk to ensure there are no leaks
- Use clear or white 100% silicone caulk for bathroom use
Common Mistakes to Avoid
- Overtightening closet bolts and cracking the toilet base - Tighten just until snug
- Using the wrong wax ring thickness for your flange height
- Not cleaning the old wax completely from the flange - This prevents proper sealing
- Lifting the toilet after setting it - This breaks the wax ring seal requiring replacement
- Forgetting to remove the rag from the drain before setting the toilet
- Not checking for leaks thoroughly before finishing - Small leaks become big problems
- Applying too much caulk and sealing the toilet completely to the floor
Tips and Tricks
- Buy a new water supply line - old ones often leak after being disturbed
- Keep the toilet boxes for easier transport and to protect the porcelain
- Install the toilet seat after everything else is done and tested
- Place shims under a rocking toilet but never over-shim
- Take photos of your old toilet setup before disassembly
- Consider upgrading to a soft-close toilet seat while you're at it
- Save the installation instructions - they contain useful troubleshooting info
When to Call a Professional
Consider hiring a professional plumber if:
- The toilet flange is severely damaged or completely broken
- You need to move the toilet location or change the rough-in distance
- The floor around the flange is soft, damaged, or needs structural repair
- You're installing a complex toilet system like a macerating or upflush toilet
- You discover major plumbing problems when removing the old toilet
- The toilet continues to leak at the base after proper installation
- You're not comfortable with the physical demands of lifting and positioning the toilet
Code Considerations
Toilet installation typically doesn't require a permit since it's a fixture replacement, but codes do specify:
- Water Efficiency: Many areas require WaterSense toilets (1.28 gallons per flush or less) for replacements
- Flange Requirements: The flange must be securely attached and at proper height
- Wax Ring: Must create a watertight seal between toilet and drain
- Water Supply: Requires a shut-off valve within reach of the toilet
- Clearances: Minimum clearances from walls and other fixtures must be maintained (typically 15 inches from center to any obstruction)
- Floor Mounting: Closet bolts must securely anchor the toilet to the flange and floor
Maintenance Tips
Regular Maintenance
- Check for leaks around the base monthly - address any water immediately
- Tighten closet bolt nuts if the toilet becomes loose
- Replace the wax ring if you notice any water seeping around the base
- Clean the tank interior annually to prevent mineral buildup
- Inspect and replace the fill valve and flapper every 5-7 years
Signs of Problems
- Water pooling around the base (damaged wax ring)
- Toilet rocks when you sit (loose bolts or uneven floor)
- Continuous running water (flapper or fill valve problem)
- Weak flush (clogged rim jets or low water level)
Cost Estimate
DIY Installation Costs
- Basic two-piece toilet: $100-300
- Mid-range efficient toilet: $250-500
- High-end comfort height toilet: $400-800
- Wax ring with sleeve: $5-10
- Closet bolts: $3-7
- Water supply line: $8-15
- Caulk and misc. supplies: $10-20
- Total DIY Cost: $126-1,352 depending on toilet choice
Professional Installation
- Professional toilet installation: $200-400
- With flange repair: $350-600
Potential Savings: DIY installation saves $200-400 in labor costs.
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