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Learn When Not To Use Plumbers Putty – 7 Situations Explained

Plumbers putty is a versatile, inexpensive sealing product that many DIYers and professionals rely on for installing and repairing sinks, setting toilet bases, and sealing pipe joints. 

But while this soft, pliable putty seems like an easy solution for all leaks and gaps, it’s not always the right material for the job.

Plumbers putty seems handy for all seals, but using it on the wrong materials like plastic threads and smooth surfaces causes leaks. 

Learn when not to use putty. Knowing when Not to use plumbers’ putty can prevent wasted time, leaks, and damage.

Types of Plumbing Connections

To understand when to avoid putty, it’s important to recognize the various types of joints and connections in plumbing systems. The three main types are:

  1. Threaded Joints – Pipe connections with machine-threaded male and female ends that twist together. Common on galvanized, black iron, and brass pipes and fittings.
  2. Slip Joints – One pipe slips loosely inside a slightly larger pipe or fitting socket. Flexible and requires no tools to connect but can pull apart under pressure. Used with PVC, CPVC, and ABS drain pipes.
  3. Solvent Weld Joints – The outside of one pipe and the inside of the fitting socket are bonded together with solvent cement adhesive. Creates a permanent, watertight connection. Used on PVC and ABS pipes.

Why Avoid Plumbers Putty on Certain Materials


While versatile, flexible plumbers’ putty has some well-known drawbacks and limitations that make it unsuitable for certain plumbing tasks. Key reasons to avoid using it include:

Plastic Threads

Putty should never be used on plastic pipe and fitting threads, including connections like PVC, CPVC, ABS, and PEX. The putty can interfere with proper tightening and bonding.

Smooth Surfaces

Putty doesn’t adhere well to non-porous materials with smooth surfaces like plastic, glass, fiberglass, acrylic, porcelain, and granite composite sinks. It can dislodge and clog drains.

Permanent Seals

Any joints intended to be permanent or solvent welded should not use putty that can work loose over time. This includes drain pipe connections.

Under Stress

Putty should not go on high-pressure pipe joints >30 PSI as it can extrude and fail to seal properly under tight clamps and threaded connections.

Gas Lines

Plumbers putty should never be used on gas supply pipes because natural gas can degrade the putty and allow dangerous leaks. Pipe dope compounds meeting code requirements should seal gas pipe threads instead.

The Wrong Putty

Hardware store plumbers’ putty should not go on expensive countertops like granite, marble, quartz, and solid surfaces which require specialized putties that won’t stain the material.

When to Avoid Plumbers Putty on Common Plumbing Jobs

Understanding when not to use putty allows choosing better alternatives and prevents problems down the road. Some specific plumbing tasks where you shouldn’t use standard putty are:

  1. Plastic or Acrylic Sink Connections – Use silicone sealant instead so bonds won’t loosen. Ensure to clean with solvents first.
  2. PVC and CPVC Pipe Joints – Use proper solvent cement only, ensuring full, even application for leak protection.
  3. PEX Tubing System – Secure metal insert and clamp fittings with manufacturer-approved lubricants instead of putty.
  4. Basket Strainer Assembly – Pack plumber’s rope around basket stems to seal sinks without staining porcelain.
  5. ABS Pipe Cementing – Bond joints with proper solvent glues formulated specifically for ABS materials.
  6. Outdoor Hose Bibs – Use thread sealing tape or paste designed for outdoor water connections with hose threads.
  7. Bathroom Sink Overflow – Seal gasket connections with silicone caulk for better adhesion and flexibility.

Alternative Sealants When You Shouldn’t Use Putty

Plumbers rely on an assortment of specialized sealants for certain situations when putty won’t work or isn’t code-approved. Top alternatives include:

  1. Silicone Caulk – Flexible seal for glass, acrylics, metals, and smooth surfaces. Withstands temperature extremes.
  2. Epoxy Putties – Can permanently seal stubborn leaks even under water. Safe for potable water contact once fully cured.
  3. PTFE Tape – Essential for sealing pipe threads 6 inches or less without damaging the threads. No adhesive properties.
  4. Liquid Pipe Sealants – Brush-on compounds that seal threaded pipe connections. Better for large-diameter, high-pressure joints.
  5. Rubber Gaskets – Custom cut seals for odd-shaped sinks and countertops. Leave no messy residue.
  6. Flange Gaskets – The Code required seals between toilets and drainage flanges to prevent leakage and gas escapes.

While plumber’s putty remains an indispensable go-to sealant for common sinks and tops, it’s not meant for every plumbing job. 

Being mindful of surfaces and connections where putty should be avoided allows for better seals using purpose-made alternatives like silicone, epoxy, tape, gaskets, and cement. 

With so many plumbing materials and joint types in homes and buildings today, having several sealant solutions on hand ensures you can complete repairs and installs properly.


Plumbers putty is undeniably handy for quick fixes and seals on countless sinks, pipe joints, and plumbing connections. But while it seems like an easy one-size-fits-all solution, putty limitations mean it’s not always the best choice. Trying to use plumbers’ putty where it doesn’t belong often leads to leaks, blockages, and damage over time. 

Knowing which materials react poorly with putty, which seals require other adhesives, and when high durability or strict codes require professional products, helps ensure repairs are reliable. With so many plumbing systems in need of seals during repairs and remodeling projects, keeping an assorted collection of putties, tapes, cement and o-rings on hand saves money, avoids improper installations, and prevents emergency callbacks. When in need of a reliable plumber in Rockford for quality plumbing repairs or installations, proper sealing products are a necessity

Though its flexibility and simplicity are appealing, taking the time to seal correctly with fitted o-rings, solvent glues, proprietary sealants, gaskets, epoxies or clamps designed specifically per application leads to leak-free plumbing that passes inspection and lasts for years. Ultimately, understanding where and when not to use that familiar tub of basic plumber putty sitting in your toolbox makes it easier to complete plumbing tasks properly.

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